44
Weak Memory Models Daniel Kroening University of Oxford, Computer Science Department
Weak Memory Models
Daniel Kroening
University of Oxford, Computer Science Department
NATO Science for Peace and Security Series
This Series presents the results of scientific meetings supported under the NATO Programme: Science for Peace and Security (SPS).
The NATO SPS Programme supports meetings in the following Key Priority areas: (1) Defence Against Terrorism; (2) Countering other Threats to Security and (3) NATO, Partner and Mediterranean Dialogue Country Priorities. The types of meeting supported are generally “Advanced Study Institutes” and “Advanced Research Workshops”. The NATO SPS Series collects together the results of these meetings. The meetings are co-organized by scientists from NATO countries and scientists from NATO’s “Partner” or “Mediterranean Dialogue” countries. The observations and recommendations made at the meetings, as well as the contents of the volumes in the Series, reflect those of participants and contributors only; they should not necessarily be regarded as reflecting NATO views or policy.
Advanced Study Institutes (ASI) are high-level tutorial courses to convey the latest developments in a subject to an advanced-level audience.
Advanced Research Workshops (ARW) are expert meetings where an intense but informal exchange of views at the frontiers of a subject aims at identifying directions for future action.
Following a transformation of the programme in 2006 the Series has been re-named and re-organised. Recent volumes on topics not related to security, which result from meetings supported under the programme earlier, may be found in the NATO Science Series.
The Series is published by IOS Press, Amsterdam, and Springer Science and Business Media, Dordrecht, in conjunction with the NATO Emerging Security Challenges Division.
Sub-Series
A. Chemistry and Biology Springer Science and Business Media B. Physics and Biophysics Springer Science and Business Media C. Environmental Security Springer Science and Business Media D. Information and Communication Security IOS Press E. Human and Societal Dynamics IOS Press
http://www.nato.int/science http://www.springer.com http://www.iospress.nl
Sub-Series D: Information and Communication Security – Vol. 36 ISSN 1874-6268 (print) ISSN 1879-8292 (online)
Outline
Motivating Example
Verifying Weak Memory with BMC
D. Kroening: Weak Memory Models
NATO Science for Peace and Security Series
This Series presents the results of scientific meetings supported under the NATO Programme: Science for Peace and Security (SPS).
The NATO SPS Programme supports meetings in the following Key Priority areas: (1) Defence Against Terrorism; (2) Countering other Threats to Security and (3) NATO, Partner and Mediterranean Dialogue Country Priorities. The types of meeting supported are generally “Advanced Study Institutes” and “Advanced Research Workshops”. The NATO SPS Series collects together the results of these meetings. The meetings are co-organized by scientists from NATO countries and scientists from NATO’s “Partner” or “Mediterranean Dialogue” countries. The observations and recommendations made at the meetings, as well as the contents of the volumes in the Series, reflect those of participants and contributors only; they should not necessarily be regarded as reflecting NATO views or policy.
Advanced Study Institutes (ASI) are high-level tutorial courses to convey the latest developments in a subject to an advanced-level audience.
Advanced Research Workshops (ARW) are expert meetings where an intense but informal exchange of views at the frontiers of a subject aims at identifying directions for future action.
Following a transformation of the programme in 2006 the Series has been re-named and re-organised. Recent volumes on topics not related to security, which result from meetings supported under the programme earlier, may be found in the NATO Science Series.
The Series is published by IOS Press, Amsterdam, and Springer Science and Business Media, Dordrecht, in conjunction with the NATO Emerging Security Challenges Division.
Sub-Series
A. Chemistry and Biology Springer Science and Business Media B. Physics and Biophysics Springer Science and Business Media C. Environmental Security Springer Science and Business Media D. Information and Communication Security IOS Press E. Human and Societal Dynamics IOS Press
http://www.nato.int/science http://www.springer.com http://www.iospress.nl
Sub-Series D: Information and Communication Security – Vol. 36 ISSN 1874-6268 (print) ISSN 1879-8292 (online)
2
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1 void worker(int i ) {2 while(! latch [ i ]);3 for (;;) {4 assert (! latch [ i ] || flag [ i ]);5 latch [ i ] = 0;6 if ( flag [ i ]) {7 flag [ i ] = 0;8 flag [( i+1)%workers] = 1;9 latch [( i+1)%workers] = 1;}
10 while(! latch [ i ]);11 }12 }
I The array latch is sharedI Each process waits to have its
latch set and then expects tohave work to do, whichconsists of passing around atoken via the array flag (line8).
I Once the process is done, itsets the latch of the processthe token was passed to (line9).
D. Kroening: Weak Memory Models
NATO Science for Peace and Security Series
This Series presents the results of scientific meetings supported under the NATO Programme: Science for Peace and Security (SPS).
The NATO SPS Programme supports meetings in the following Key Priority areas: (1) Defence Against Terrorism; (2) Countering other Threats to Security and (3) NATO, Partner and Mediterranean Dialogue Country Priorities. The types of meeting supported are generally “Advanced Study Institutes” and “Advanced Research Workshops”. The NATO SPS Series collects together the results of these meetings. The meetings are co-organized by scientists from NATO countries and scientists from NATO’s “Partner” or “Mediterranean Dialogue” countries. The observations and recommendations made at the meetings, as well as the contents of the volumes in the Series, reflect those of participants and contributors only; they should not necessarily be regarded as reflecting NATO views or policy.
Advanced Study Institutes (ASI) are high-level tutorial courses to convey the latest developments in a subject to an advanced-level audience.
Advanced Research Workshops (ARW) are expert meetings where an intense but informal exchange of views at the frontiers of a subject aims at identifying directions for future action.
Following a transformation of the programme in 2006 the Series has been re-named and re-organised. Recent volumes on topics not related to security, which result from meetings supported under the programme earlier, may be found in the NATO Science Series.
The Series is published by IOS Press, Amsterdam, and Springer Science and Business Media, Dordrecht, in conjunction with the NATO Emerging Security Challenges Division.
Sub-Series
A. Chemistry and Biology Springer Science and Business Media B. Physics and Biophysics Springer Science and Business Media C. Environmental Security Springer Science and Business Media D. Information and Communication Security IOS Press E. Human and Societal Dynamics IOS Press
http://www.nato.int/science http://www.springer.com http://www.iospress.nl
Sub-Series D: Information and Communication Security – Vol. 36 ISSN 1874-6268 (print) ISSN 1879-8292 (online)
3
PostgreSQL Worker Ring
0
1
2
34
5
6
7
flag[0]flag[0]
latch[0]
0flag[0]
latch[0]
0flag[0]
00
flag[1]
0
flag[1]
latch[1]1flag[1]
latch[1]1flag[1]
11
flag[2]
1
flag[2]
latch[2]2 flag[2]
latch[2]2 flag[2]2
D. Kroening: Weak Memory Models
NATO Science for Peace and Security Series
This Series presents the results of scientific meetings supported under the NATO Programme: Science for Peace and Security (SPS).
The NATO SPS Programme supports meetings in the following Key Priority areas: (1) Defence Against Terrorism; (2) Countering other Threats to Security and (3) NATO, Partner and Mediterranean Dialogue Country Priorities. The types of meeting supported are generally “Advanced Study Institutes” and “Advanced Research Workshops”. The NATO SPS Series collects together the results of these meetings. The meetings are co-organized by scientists from NATO countries and scientists from NATO’s “Partner” or “Mediterranean Dialogue” countries. The observations and recommendations made at the meetings, as well as the contents of the volumes in the Series, reflect those of participants and contributors only; they should not necessarily be regarded as reflecting NATO views or policy.
Advanced Study Institutes (ASI) are high-level tutorial courses to convey the latest developments in a subject to an advanced-level audience.
Advanced Research Workshops (ARW) are expert meetings where an intense but informal exchange of views at the frontiers of a subject aims at identifying directions for future action.
Following a transformation of the programme in 2006 the Series has been re-named and re-organised. Recent volumes on topics not related to security, which result from meetings supported under the programme earlier, may be found in the NATO Science Series.
The Series is published by IOS Press, Amsterdam, and Springer Science and Business Media, Dordrecht, in conjunction with the NATO Emerging Security Challenges Division.
Sub-Series
A. Chemistry and Biology Springer Science and Business Media B. Physics and Biophysics Springer Science and Business Media C. Environmental Security Springer Science and Business Media D. Information and Communication Security IOS Press E. Human and Societal Dynamics IOS Press
http://www.nato.int/science http://www.springer.com http://www.iospress.nl
Sub-Series D: Information and Communication Security – Vol. 36 ISSN 1874-6268 (print) ISSN 1879-8292 (online)
4
PostgreSQL Worker Ring
0
1
2
34
5
6
7flag[0]
flag[0]
latch[0]
0flag[0]
latch[0]
0flag[0]
00
flag[1]
0
flag[1]
latch[1]1flag[1]
latch[1]1flag[1]
11
flag[2]
1
flag[2]
latch[2]2 flag[2]
latch[2]2 flag[2]2
D. Kroening: Weak Memory Models
NATO Science for Peace and Security Series
This Series presents the results of scientific meetings supported under the NATO Programme: Science for Peace and Security (SPS).
The NATO SPS Programme supports meetings in the following Key Priority areas: (1) Defence Against Terrorism; (2) Countering other Threats to Security and (3) NATO, Partner and Mediterranean Dialogue Country Priorities. The types of meeting supported are generally “Advanced Study Institutes” and “Advanced Research Workshops”. The NATO SPS Series collects together the results of these meetings. The meetings are co-organized by scientists from NATO countries and scientists from NATO’s “Partner” or “Mediterranean Dialogue” countries. The observations and recommendations made at the meetings, as well as the contents of the volumes in the Series, reflect those of participants and contributors only; they should not necessarily be regarded as reflecting NATO views or policy.
Advanced Study Institutes (ASI) are high-level tutorial courses to convey the latest developments in a subject to an advanced-level audience.
Advanced Research Workshops (ARW) are expert meetings where an intense but informal exchange of views at the frontiers of a subject aims at identifying directions for future action.
Following a transformation of the programme in 2006 the Series has been re-named and re-organised. Recent volumes on topics not related to security, which result from meetings supported under the programme earlier, may be found in the NATO Science Series.
The Series is published by IOS Press, Amsterdam, and Springer Science and Business Media, Dordrecht, in conjunction with the NATO Emerging Security Challenges Division.
Sub-Series
A. Chemistry and Biology Springer Science and Business Media B. Physics and Biophysics Springer Science and Business Media C. Environmental Security Springer Science and Business Media D. Information and Communication Security IOS Press E. Human and Societal Dynamics IOS Press
http://www.nato.int/science http://www.springer.com http://www.iospress.nl
Sub-Series D: Information and Communication Security – Vol. 36 ISSN 1874-6268 (print) ISSN 1879-8292 (online)
4
PostgreSQL Worker Ring
0
1
2
34
5
6
7
flag[0]
flag[0]
latch[0]
0flag[0]
latch[0]
0flag[0]
00
flag[1]
0
flag[1]
latch[1]1flag[1]
latch[1]1flag[1]
11
flag[2]
1
flag[2]
latch[2]2 flag[2]
latch[2]2 flag[2]2
D. Kroening: Weak Memory Models
NATO Science for Peace and Security Series
This Series presents the results of scientific meetings supported under the NATO Programme: Science for Peace and Security (SPS).
The NATO SPS Programme supports meetings in the following Key Priority areas: (1) Defence Against Terrorism; (2) Countering other Threats to Security and (3) NATO, Partner and Mediterranean Dialogue Country Priorities. The types of meeting supported are generally “Advanced Study Institutes” and “Advanced Research Workshops”. The NATO SPS Series collects together the results of these meetings. The meetings are co-organized by scientists from NATO countries and scientists from NATO’s “Partner” or “Mediterranean Dialogue” countries. The observations and recommendations made at the meetings, as well as the contents of the volumes in the Series, reflect those of participants and contributors only; they should not necessarily be regarded as reflecting NATO views or policy.
Advanced Study Institutes (ASI) are high-level tutorial courses to convey the latest developments in a subject to an advanced-level audience.
Advanced Research Workshops (ARW) are expert meetings where an intense but informal exchange of views at the frontiers of a subject aims at identifying directions for future action.
Following a transformation of the programme in 2006 the Series has been re-named and re-organised. Recent volumes on topics not related to security, which result from meetings supported under the programme earlier, may be found in the NATO Science Series.
The Series is published by IOS Press, Amsterdam, and Springer Science and Business Media, Dordrecht, in conjunction with the NATO Emerging Security Challenges Division.
Sub-Series
A. Chemistry and Biology Springer Science and Business Media B. Physics and Biophysics Springer Science and Business Media C. Environmental Security Springer Science and Business Media D. Information and Communication Security IOS Press E. Human and Societal Dynamics IOS Press
http://www.nato.int/science http://www.springer.com http://www.iospress.nl
Sub-Series D: Information and Communication Security – Vol. 36 ISSN 1874-6268 (print) ISSN 1879-8292 (online)
4
PostgreSQL Worker Ring
0
1
2
34
5
6
7
flag[0]flag[0]
latch[0]
0flag[0]
latch[0]
0flag[0]
00
flag[1]
0
flag[1]
latch[1]1flag[1]
latch[1]1flag[1]
11
flag[2]
1
flag[2]
latch[2]2 flag[2]
latch[2]2 flag[2]2
D. Kroening: Weak Memory Models
NATO Science for Peace and Security Series
This Series presents the results of scientific meetings supported under the NATO Programme: Science for Peace and Security (SPS).
The NATO SPS Programme supports meetings in the following Key Priority areas: (1) Defence Against Terrorism; (2) Countering other Threats to Security and (3) NATO, Partner and Mediterranean Dialogue Country Priorities. The types of meeting supported are generally “Advanced Study Institutes” and “Advanced Research Workshops”. The NATO SPS Series collects together the results of these meetings. The meetings are co-organized by scientists from NATO countries and scientists from NATO’s “Partner” or “Mediterranean Dialogue” countries. The observations and recommendations made at the meetings, as well as the contents of the volumes in the Series, reflect those of participants and contributors only; they should not necessarily be regarded as reflecting NATO views or policy.
Advanced Study Institutes (ASI) are high-level tutorial courses to convey the latest developments in a subject to an advanced-level audience.
Advanced Research Workshops (ARW) are expert meetings where an intense but informal exchange of views at the frontiers of a subject aims at identifying directions for future action.
Following a transformation of the programme in 2006 the Series has been re-named and re-organised. Recent volumes on topics not related to security, which result from meetings supported under the programme earlier, may be found in the NATO Science Series.
The Series is published by IOS Press, Amsterdam, and Springer Science and Business Media, Dordrecht, in conjunction with the NATO Emerging Security Challenges Division.
Sub-Series
A. Chemistry and Biology Springer Science and Business Media B. Physics and Biophysics Springer Science and Business Media C. Environmental Security Springer Science and Business Media D. Information and Communication Security IOS Press E. Human and Societal Dynamics IOS Press
http://www.nato.int/science http://www.springer.com http://www.iospress.nl
Sub-Series D: Information and Communication Security – Vol. 36 ISSN 1874-6268 (print) ISSN 1879-8292 (online)
4
PostgreSQL Worker Ring
0
1
2
34
5
6
7
flag[0]flag[0]
latch[0]
0flag[0]
latch[0]
0flag[0]
00
flag[1]
0
flag[1]
latch[1]1flag[1]
latch[1]1flag[1]
11
flag[2]
1
flag[2]
latch[2]2 flag[2]
latch[2]2 flag[2]2
D. Kroening: Weak Memory Models
NATO Science for Peace and Security Series
This Series presents the results of scientific meetings supported under the NATO Programme: Science for Peace and Security (SPS).
The NATO SPS Programme supports meetings in the following Key Priority areas: (1) Defence Against Terrorism; (2) Countering other Threats to Security and (3) NATO, Partner and Mediterranean Dialogue Country Priorities. The types of meeting supported are generally “Advanced Study Institutes” and “Advanced Research Workshops”. The NATO SPS Series collects together the results of these meetings. The meetings are co-organized by scientists from NATO countries and scientists from NATO’s “Partner” or “Mediterranean Dialogue” countries. The observations and recommendations made at the meetings, as well as the contents of the volumes in the Series, reflect those of participants and contributors only; they should not necessarily be regarded as reflecting NATO views or policy.
Advanced Study Institutes (ASI) are high-level tutorial courses to convey the latest developments in a subject to an advanced-level audience.
Advanced Research Workshops (ARW) are expert meetings where an intense but informal exchange of views at the frontiers of a subject aims at identifying directions for future action.
Following a transformation of the programme in 2006 the Series has been re-named and re-organised. Recent volumes on topics not related to security, which result from meetings supported under the programme earlier, may be found in the NATO Science Series.
The Series is published by IOS Press, Amsterdam, and Springer Science and Business Media, Dordrecht, in conjunction with the NATO Emerging Security Challenges Division.
Sub-Series
A. Chemistry and Biology Springer Science and Business Media B. Physics and Biophysics Springer Science and Business Media C. Environmental Security Springer Science and Business Media D. Information and Communication Security IOS Press E. Human and Societal Dynamics IOS Press
http://www.nato.int/science http://www.springer.com http://www.iospress.nl
Sub-Series D: Information and Communication Security – Vol. 36 ISSN 1874-6268 (print) ISSN 1879-8292 (online)
4
PostgreSQL Worker Ring
0
1
2
34
5
6
7
flag[0]flag[0]
latch[0]
0flag[0]
latch[0]
0flag[0]
0
0
flag[1]
0
flag[1]
latch[1]1flag[1]
latch[1]1flag[1]
11
flag[2]
1
flag[2]
latch[2]2 flag[2]
latch[2]2 flag[2]2
D. Kroening: Weak Memory Models
NATO Science for Peace and Security Series
This Series presents the results of scientific meetings supported under the NATO Programme: Science for Peace and Security (SPS).
The NATO SPS Programme supports meetings in the following Key Priority areas: (1) Defence Against Terrorism; (2) Countering other Threats to Security and (3) NATO, Partner and Mediterranean Dialogue Country Priorities. The types of meeting supported are generally “Advanced Study Institutes” and “Advanced Research Workshops”. The NATO SPS Series collects together the results of these meetings. The meetings are co-organized by scientists from NATO countries and scientists from NATO’s “Partner” or “Mediterranean Dialogue” countries. The observations and recommendations made at the meetings, as well as the contents of the volumes in the Series, reflect those of participants and contributors only; they should not necessarily be regarded as reflecting NATO views or policy.
Advanced Study Institutes (ASI) are high-level tutorial courses to convey the latest developments in a subject to an advanced-level audience.
Advanced Research Workshops (ARW) are expert meetings where an intense but informal exchange of views at the frontiers of a subject aims at identifying directions for future action.
Following a transformation of the programme in 2006 the Series has been re-named and re-organised. Recent volumes on topics not related to security, which result from meetings supported under the programme earlier, may be found in the NATO Science Series.
The Series is published by IOS Press, Amsterdam, and Springer Science and Business Media, Dordrecht, in conjunction with the NATO Emerging Security Challenges Division.
Sub-Series
A. Chemistry and Biology Springer Science and Business Media B. Physics and Biophysics Springer Science and Business Media C. Environmental Security Springer Science and Business Media D. Information and Communication Security IOS Press E. Human and Societal Dynamics IOS Press
http://www.nato.int/science http://www.springer.com http://www.iospress.nl
Sub-Series D: Information and Communication Security – Vol. 36 ISSN 1874-6268 (print) ISSN 1879-8292 (online)
4
PostgreSQL Worker Ring
0
1
2
34
5
6
7
flag[0]flag[0]
latch[0]
0flag[0]
latch[0]
0flag[0]
0
0
flag[1]
0
flag[1]
latch[1]1flag[1]
latch[1]1flag[1]
11
flag[2]
1
flag[2]
latch[2]2 flag[2]
latch[2]2 flag[2]2
D. Kroening: Weak Memory Models
NATO Science for Peace and Security Series
This Series presents the results of scientific meetings supported under the NATO Programme: Science for Peace and Security (SPS).
The NATO SPS Programme supports meetings in the following Key Priority areas: (1) Defence Against Terrorism; (2) Countering other Threats to Security and (3) NATO, Partner and Mediterranean Dialogue Country Priorities. The types of meeting supported are generally “Advanced Study Institutes” and “Advanced Research Workshops”. The NATO SPS Series collects together the results of these meetings. The meetings are co-organized by scientists from NATO countries and scientists from NATO’s “Partner” or “Mediterranean Dialogue” countries. The observations and recommendations made at the meetings, as well as the contents of the volumes in the Series, reflect those of participants and contributors only; they should not necessarily be regarded as reflecting NATO views or policy.
Advanced Study Institutes (ASI) are high-level tutorial courses to convey the latest developments in a subject to an advanced-level audience.
Advanced Research Workshops (ARW) are expert meetings where an intense but informal exchange of views at the frontiers of a subject aims at identifying directions for future action.
Following a transformation of the programme in 2006 the Series has been re-named and re-organised. Recent volumes on topics not related to security, which result from meetings supported under the programme earlier, may be found in the NATO Science Series.
The Series is published by IOS Press, Amsterdam, and Springer Science and Business Media, Dordrecht, in conjunction with the NATO Emerging Security Challenges Division.
Sub-Series
A. Chemistry and Biology Springer Science and Business Media B. Physics and Biophysics Springer Science and Business Media C. Environmental Security Springer Science and Business Media D. Information and Communication Security IOS Press E. Human and Societal Dynamics IOS Press
http://www.nato.int/science http://www.springer.com http://www.iospress.nl
Sub-Series D: Information and Communication Security – Vol. 36 ISSN 1874-6268 (print) ISSN 1879-8292 (online)
4
PostgreSQL Worker Ring
0
1
2
34
5
6
7
flag[0]flag[0]
latch[0]
0flag[0]
latch[0]
0flag[0]
00
flag[1]
0
flag[1]
latch[1]
1flag[1]
latch[1]1flag[1]
11
flag[2]
1
flag[2]
latch[2]2 flag[2]
latch[2]2 flag[2]2
D. Kroening: Weak Memory Models
NATO Science for Peace and Security Series
This Series presents the results of scientific meetings supported under the NATO Programme: Science for Peace and Security (SPS).
The NATO SPS Programme supports meetings in the following Key Priority areas: (1) Defence Against Terrorism; (2) Countering other Threats to Security and (3) NATO, Partner and Mediterranean Dialogue Country Priorities. The types of meeting supported are generally “Advanced Study Institutes” and “Advanced Research Workshops”. The NATO SPS Series collects together the results of these meetings. The meetings are co-organized by scientists from NATO countries and scientists from NATO’s “Partner” or “Mediterranean Dialogue” countries. The observations and recommendations made at the meetings, as well as the contents of the volumes in the Series, reflect those of participants and contributors only; they should not necessarily be regarded as reflecting NATO views or policy.
Advanced Study Institutes (ASI) are high-level tutorial courses to convey the latest developments in a subject to an advanced-level audience.
Advanced Research Workshops (ARW) are expert meetings where an intense but informal exchange of views at the frontiers of a subject aims at identifying directions for future action.
Following a transformation of the programme in 2006 the Series has been re-named and re-organised. Recent volumes on topics not related to security, which result from meetings supported under the programme earlier, may be found in the NATO Science Series.
The Series is published by IOS Press, Amsterdam, and Springer Science and Business Media, Dordrecht, in conjunction with the NATO Emerging Security Challenges Division.
Sub-Series
A. Chemistry and Biology Springer Science and Business Media B. Physics and Biophysics Springer Science and Business Media C. Environmental Security Springer Science and Business Media D. Information and Communication Security IOS Press E. Human and Societal Dynamics IOS Press
http://www.nato.int/science http://www.springer.com http://www.iospress.nl
Sub-Series D: Information and Communication Security – Vol. 36 ISSN 1874-6268 (print) ISSN 1879-8292 (online)
4
PostgreSQL Worker Ring
0
1
2
34
5
6
7
flag[0]flag[0]
latch[0]
0flag[0]
latch[0]
0flag[0]
00
flag[1]
0
flag[1]
latch[1]
1flag[1]
latch[1]
1flag[1]
11
flag[2]
1
flag[2]
latch[2]2 flag[2]
latch[2]2 flag[2]2
D. Kroening: Weak Memory Models
NATO Science for Peace and Security Series
This Series presents the results of scientific meetings supported under the NATO Programme: Science for Peace and Security (SPS).
The NATO SPS Programme supports meetings in the following Key Priority areas: (1) Defence Against Terrorism; (2) Countering other Threats to Security and (3) NATO, Partner and Mediterranean Dialogue Country Priorities. The types of meeting supported are generally “Advanced Study Institutes” and “Advanced Research Workshops”. The NATO SPS Series collects together the results of these meetings. The meetings are co-organized by scientists from NATO countries and scientists from NATO’s “Partner” or “Mediterranean Dialogue” countries. The observations and recommendations made at the meetings, as well as the contents of the volumes in the Series, reflect those of participants and contributors only; they should not necessarily be regarded as reflecting NATO views or policy.
Advanced Study Institutes (ASI) are high-level tutorial courses to convey the latest developments in a subject to an advanced-level audience.
Advanced Research Workshops (ARW) are expert meetings where an intense but informal exchange of views at the frontiers of a subject aims at identifying directions for future action.
Following a transformation of the programme in 2006 the Series has been re-named and re-organised. Recent volumes on topics not related to security, which result from meetings supported under the programme earlier, may be found in the NATO Science Series.
The Series is published by IOS Press, Amsterdam, and Springer Science and Business Media, Dordrecht, in conjunction with the NATO Emerging Security Challenges Division.
Sub-Series
A. Chemistry and Biology Springer Science and Business Media B. Physics and Biophysics Springer Science and Business Media C. Environmental Security Springer Science and Business Media D. Information and Communication Security IOS Press E. Human and Societal Dynamics IOS Press
http://www.nato.int/science http://www.springer.com http://www.iospress.nl
Sub-Series D: Information and Communication Security – Vol. 36 ISSN 1874-6268 (print) ISSN 1879-8292 (online)
4
PostgreSQL Worker Ring
0
1
2
34
5
6
7
flag[0]flag[0]
latch[0]
0flag[0]
latch[0]
0flag[0]
00
flag[1]
0
flag[1]
latch[1]1flag[1]
latch[1]
1flag[1]
11
flag[2]
1
flag[2]
latch[2]2 flag[2]
latch[2]2 flag[2]2
D. Kroening: Weak Memory Models
NATO Science for Peace and Security Series
This Series presents the results of scientific meetings supported under the NATO Programme: Science for Peace and Security (SPS).
The NATO SPS Programme supports meetings in the following Key Priority areas: (1) Defence Against Terrorism; (2) Countering other Threats to Security and (3) NATO, Partner and Mediterranean Dialogue Country Priorities. The types of meeting supported are generally “Advanced Study Institutes” and “Advanced Research Workshops”. The NATO SPS Series collects together the results of these meetings. The meetings are co-organized by scientists from NATO countries and scientists from NATO’s “Partner” or “Mediterranean Dialogue” countries. The observations and recommendations made at the meetings, as well as the contents of the volumes in the Series, reflect those of participants and contributors only; they should not necessarily be regarded as reflecting NATO views or policy.
Advanced Study Institutes (ASI) are high-level tutorial courses to convey the latest developments in a subject to an advanced-level audience.
Advanced Research Workshops (ARW) are expert meetings where an intense but informal exchange of views at the frontiers of a subject aims at identifying directions for future action.
Following a transformation of the programme in 2006 the Series has been re-named and re-organised. Recent volumes on topics not related to security, which result from meetings supported under the programme earlier, may be found in the NATO Science Series.
The Series is published by IOS Press, Amsterdam, and Springer Science and Business Media, Dordrecht, in conjunction with the NATO Emerging Security Challenges Division.
Sub-Series
A. Chemistry and Biology Springer Science and Business Media B. Physics and Biophysics Springer Science and Business Media C. Environmental Security Springer Science and Business Media D. Information and Communication Security IOS Press E. Human and Societal Dynamics IOS Press
http://www.nato.int/science http://www.springer.com http://www.iospress.nl
Sub-Series D: Information and Communication Security – Vol. 36 ISSN 1874-6268 (print) ISSN 1879-8292 (online)
4
PostgreSQL Worker Ring
0
1
2
34
5
6
7
flag[0]flag[0]
latch[0]
0flag[0]
latch[0]
0flag[0]
00
flag[1]
0
flag[1]
latch[1]1flag[1]
latch[1]1flag[1]
1
1
flag[2]
1
flag[2]
latch[2]2 flag[2]
latch[2]2 flag[2]2
D. Kroening: Weak Memory Models
NATO Science for Peace and Security Series
This Series presents the results of scientific meetings supported under the NATO Programme: Science for Peace and Security (SPS).
The NATO SPS Programme supports meetings in the following Key Priority areas: (1) Defence Against Terrorism; (2) Countering other Threats to Security and (3) NATO, Partner and Mediterranean Dialogue Country Priorities. The types of meeting supported are generally “Advanced Study Institutes” and “Advanced Research Workshops”. The NATO SPS Series collects together the results of these meetings. The meetings are co-organized by scientists from NATO countries and scientists from NATO’s “Partner” or “Mediterranean Dialogue” countries. The observations and recommendations made at the meetings, as well as the contents of the volumes in the Series, reflect those of participants and contributors only; they should not necessarily be regarded as reflecting NATO views or policy.
Advanced Study Institutes (ASI) are high-level tutorial courses to convey the latest developments in a subject to an advanced-level audience.
Advanced Research Workshops (ARW) are expert meetings where an intense but informal exchange of views at the frontiers of a subject aims at identifying directions for future action.
Following a transformation of the programme in 2006 the Series has been re-named and re-organised. Recent volumes on topics not related to security, which result from meetings supported under the programme earlier, may be found in the NATO Science Series.
The Series is published by IOS Press, Amsterdam, and Springer Science and Business Media, Dordrecht, in conjunction with the NATO Emerging Security Challenges Division.
Sub-Series
A. Chemistry and Biology Springer Science and Business Media B. Physics and Biophysics Springer Science and Business Media C. Environmental Security Springer Science and Business Media D. Information and Communication Security IOS Press E. Human and Societal Dynamics IOS Press
http://www.nato.int/science http://www.springer.com http://www.iospress.nl
Sub-Series D: Information and Communication Security – Vol. 36 ISSN 1874-6268 (print) ISSN 1879-8292 (online)
4
PostgreSQL Worker Ring
0
1
2
34
5
6
7
flag[0]flag[0]
latch[0]
0flag[0]
latch[0]
0flag[0]
00
flag[1]
0
flag[1]
latch[1]1flag[1]
latch[1]1flag[1]
1
1
flag[2]
1
flag[2]
latch[2]2 flag[2]
latch[2]2 flag[2]2
D. Kroening: Weak Memory Models
NATO Science for Peace and Security Series
This Series presents the results of scientific meetings supported under the NATO Programme: Science for Peace and Security (SPS).
The NATO SPS Programme supports meetings in the following Key Priority areas: (1) Defence Against Terrorism; (2) Countering other Threats to Security and (3) NATO, Partner and Mediterranean Dialogue Country Priorities. The types of meeting supported are generally “Advanced Study Institutes” and “Advanced Research Workshops”. The NATO SPS Series collects together the results of these meetings. The meetings are co-organized by scientists from NATO countries and scientists from NATO’s “Partner” or “Mediterranean Dialogue” countries. The observations and recommendations made at the meetings, as well as the contents of the volumes in the Series, reflect those of participants and contributors only; they should not necessarily be regarded as reflecting NATO views or policy.
Advanced Study Institutes (ASI) are high-level tutorial courses to convey the latest developments in a subject to an advanced-level audience.
Advanced Research Workshops (ARW) are expert meetings where an intense but informal exchange of views at the frontiers of a subject aims at identifying directions for future action.
Following a transformation of the programme in 2006 the Series has been re-named and re-organised. Recent volumes on topics not related to security, which result from meetings supported under the programme earlier, may be found in the NATO Science Series.
The Series is published by IOS Press, Amsterdam, and Springer Science and Business Media, Dordrecht, in conjunction with the NATO Emerging Security Challenges Division.
Sub-Series
A. Chemistry and Biology Springer Science and Business Media B. Physics and Biophysics Springer Science and Business Media C. Environmental Security Springer Science and Business Media D. Information and Communication Security IOS Press E. Human and Societal Dynamics IOS Press
http://www.nato.int/science http://www.springer.com http://www.iospress.nl
Sub-Series D: Information and Communication Security – Vol. 36 ISSN 1874-6268 (print) ISSN 1879-8292 (online)
4
PostgreSQL Worker Ring
0
1
2
34
5
6
7
flag[0]flag[0]
latch[0]
0flag[0]
latch[0]
0flag[0]
00
flag[1]
0
flag[1]
latch[1]1flag[1]
latch[1]1flag[1]
11
flag[2]
1
flag[2]
latch[2]
2 flag[2]
latch[2]2 flag[2]2
D. Kroening: Weak Memory Models
NATO Science for Peace and Security Series
This Series presents the results of scientific meetings supported under the NATO Programme: Science for Peace and Security (SPS).
The NATO SPS Programme supports meetings in the following Key Priority areas: (1) Defence Against Terrorism; (2) Countering other Threats to Security and (3) NATO, Partner and Mediterranean Dialogue Country Priorities. The types of meeting supported are generally “Advanced Study Institutes” and “Advanced Research Workshops”. The NATO SPS Series collects together the results of these meetings. The meetings are co-organized by scientists from NATO countries and scientists from NATO’s “Partner” or “Mediterranean Dialogue” countries. The observations and recommendations made at the meetings, as well as the contents of the volumes in the Series, reflect those of participants and contributors only; they should not necessarily be regarded as reflecting NATO views or policy.
Advanced Study Institutes (ASI) are high-level tutorial courses to convey the latest developments in a subject to an advanced-level audience.
Advanced Research Workshops (ARW) are expert meetings where an intense but informal exchange of views at the frontiers of a subject aims at identifying directions for future action.
Following a transformation of the programme in 2006 the Series has been re-named and re-organised. Recent volumes on topics not related to security, which result from meetings supported under the programme earlier, may be found in the NATO Science Series.
The Series is published by IOS Press, Amsterdam, and Springer Science and Business Media, Dordrecht, in conjunction with the NATO Emerging Security Challenges Division.
Sub-Series
A. Chemistry and Biology Springer Science and Business Media B. Physics and Biophysics Springer Science and Business Media C. Environmental Security Springer Science and Business Media D. Information and Communication Security IOS Press E. Human and Societal Dynamics IOS Press
http://www.nato.int/science http://www.springer.com http://www.iospress.nl
Sub-Series D: Information and Communication Security – Vol. 36 ISSN 1874-6268 (print) ISSN 1879-8292 (online)
4
PostgreSQL Worker Ring
0
1
2
34
5
6
7
flag[0]flag[0]
latch[0]
0flag[0]
latch[0]
0flag[0]
00
flag[1]
0
flag[1]
latch[1]1flag[1]
latch[1]1flag[1]
11
flag[2]
1
flag[2]
latch[2]
2 flag[2]
latch[2]
2 flag[2]2
D. Kroening: Weak Memory Models
NATO Science for Peace and Security Series
This Series presents the results of scientific meetings supported under the NATO Programme: Science for Peace and Security (SPS).
The NATO SPS Programme supports meetings in the following Key Priority areas: (1) Defence Against Terrorism; (2) Countering other Threats to Security and (3) NATO, Partner and Mediterranean Dialogue Country Priorities. The types of meeting supported are generally “Advanced Study Institutes” and “Advanced Research Workshops”. The NATO SPS Series collects together the results of these meetings. The meetings are co-organized by scientists from NATO countries and scientists from NATO’s “Partner” or “Mediterranean Dialogue” countries. The observations and recommendations made at the meetings, as well as the contents of the volumes in the Series, reflect those of participants and contributors only; they should not necessarily be regarded as reflecting NATO views or policy.
Advanced Study Institutes (ASI) are high-level tutorial courses to convey the latest developments in a subject to an advanced-level audience.
Advanced Research Workshops (ARW) are expert meetings where an intense but informal exchange of views at the frontiers of a subject aims at identifying directions for future action.
Following a transformation of the programme in 2006 the Series has been re-named and re-organised. Recent volumes on topics not related to security, which result from meetings supported under the programme earlier, may be found in the NATO Science Series.
The Series is published by IOS Press, Amsterdam, and Springer Science and Business Media, Dordrecht, in conjunction with the NATO Emerging Security Challenges Division.
Sub-Series
A. Chemistry and Biology Springer Science and Business Media B. Physics and Biophysics Springer Science and Business Media C. Environmental Security Springer Science and Business Media D. Information and Communication Security IOS Press E. Human and Societal Dynamics IOS Press
http://www.nato.int/science http://www.springer.com http://www.iospress.nl
Sub-Series D: Information and Communication Security – Vol. 36 ISSN 1874-6268 (print) ISSN 1879-8292 (online)
4
PostgreSQL Worker Ring
0
1
2
34
5
6
7
flag[0]flag[0]
latch[0]
0flag[0]
latch[0]
0flag[0]
00
flag[1]
0
flag[1]
latch[1]1flag[1]
latch[1]1flag[1]
11
flag[2]
1
flag[2]
latch[2]2 flag[2]
latch[2]
2 flag[2]
2
D. Kroening: Weak Memory Models
NATO Science for Peace and Security Series
This Series presents the results of scientific meetings supported under the NATO Programme: Science for Peace and Security (SPS).
The NATO SPS Programme supports meetings in the following Key Priority areas: (1) Defence Against Terrorism; (2) Countering other Threats to Security and (3) NATO, Partner and Mediterranean Dialogue Country Priorities. The types of meeting supported are generally “Advanced Study Institutes” and “Advanced Research Workshops”. The NATO SPS Series collects together the results of these meetings. The meetings are co-organized by scientists from NATO countries and scientists from NATO’s “Partner” or “Mediterranean Dialogue” countries. The observations and recommendations made at the meetings, as well as the contents of the volumes in the Series, reflect those of participants and contributors only; they should not necessarily be regarded as reflecting NATO views or policy.
Advanced Study Institutes (ASI) are high-level tutorial courses to convey the latest developments in a subject to an advanced-level audience.
Advanced Research Workshops (ARW) are expert meetings where an intense but informal exchange of views at the frontiers of a subject aims at identifying directions for future action.
Following a transformation of the programme in 2006 the Series has been re-named and re-organised. Recent volumes on topics not related to security, which result from meetings supported under the programme earlier, may be found in the NATO Science Series.
The Series is published by IOS Press, Amsterdam, and Springer Science and Business Media, Dordrecht, in conjunction with the NATO Emerging Security Challenges Division.
Sub-Series
A. Chemistry and Biology Springer Science and Business Media B. Physics and Biophysics Springer Science and Business Media C. Environmental Security Springer Science and Business Media D. Information and Communication Security IOS Press E. Human and Societal Dynamics IOS Press
http://www.nato.int/science http://www.springer.com http://www.iospress.nl
Sub-Series D: Information and Communication Security – Vol. 36 ISSN 1874-6268 (print) ISSN 1879-8292 (online)
4
PostgreSQL Worker Ring
0
1
2
34
5
6
7
flag[0]flag[0]
latch[0]
0flag[0]
latch[0]
0flag[0]
00
flag[1]
0
flag[1]
latch[1]1flag[1]
latch[1]1flag[1]
11
flag[2]
1
flag[2]
latch[2]2 flag[2]
latch[2]2 flag[2]
2
D. Kroening: Weak Memory Models
NATO Science for Peace and Security Series
This Series presents the results of scientific meetings supported under the NATO Programme: Science for Peace and Security (SPS).
The NATO SPS Programme supports meetings in the following Key Priority areas: (1) Defence Against Terrorism; (2) Countering other Threats to Security and (3) NATO, Partner and Mediterranean Dialogue Country Priorities. The types of meeting supported are generally “Advanced Study Institutes” and “Advanced Research Workshops”. The NATO SPS Series collects together the results of these meetings. The meetings are co-organized by scientists from NATO countries and scientists from NATO’s “Partner” or “Mediterranean Dialogue” countries. The observations and recommendations made at the meetings, as well as the contents of the volumes in the Series, reflect those of participants and contributors only; they should not necessarily be regarded as reflecting NATO views or policy.
Advanced Study Institutes (ASI) are high-level tutorial courses to convey the latest developments in a subject to an advanced-level audience.
Advanced Research Workshops (ARW) are expert meetings where an intense but informal exchange of views at the frontiers of a subject aims at identifying directions for future action.
Following a transformation of the programme in 2006 the Series has been re-named and re-organised. Recent volumes on topics not related to security, which result from meetings supported under the programme earlier, may be found in the NATO Science Series.
The Series is published by IOS Press, Amsterdam, and Springer Science and Business Media, Dordrecht, in conjunction with the NATO Emerging Security Challenges Division.
Sub-Series
A. Chemistry and Biology Springer Science and Business Media B. Physics and Biophysics Springer Science and Business Media C. Environmental Security Springer Science and Business Media D. Information and Communication Security IOS Press E. Human and Societal Dynamics IOS Press
http://www.nato.int/science http://www.springer.com http://www.iospress.nl
Sub-Series D: Information and Communication Security – Vol. 36 ISSN 1874-6268 (print) ISSN 1879-8292 (online)
4
PostgreSQL Worker Ring
I Starvation seemingly cannot occur:when a process is woken up, it has work to do
I Yet, the PostgreSQL developers occasionally observedthat the wait in line 10 (which in the original code isbounded in time) would time out, thus signalling starvationof the ring of processes
I Manual inspection identified the memory model of theplatform as possible culprit:the processor sometimes delays the write in line 8 untilafter the latch had been set
D. Kroening: Weak Memory Models
NATO Science for Peace and Security Series
This Series presents the results of scientific meetings supported under the NATO Programme: Science for Peace and Security (SPS).
The NATO SPS Programme supports meetings in the following Key Priority areas: (1) Defence Against Terrorism; (2) Countering other Threats to Security and (3) NATO, Partner and Mediterranean Dialogue Country Priorities. The types of meeting supported are generally “Advanced Study Institutes” and “Advanced Research Workshops”. The NATO SPS Series collects together the results of these meetings. The meetings are co-organized by scientists from NATO countries and scientists from NATO’s “Partner” or “Mediterranean Dialogue” countries. The observations and recommendations made at the meetings, as well as the contents of the volumes in the Series, reflect those of participants and contributors only; they should not necessarily be regarded as reflecting NATO views or policy.
Advanced Study Institutes (ASI) are high-level tutorial courses to convey the latest developments in a subject to an advanced-level audience.
Advanced Research Workshops (ARW) are expert meetings where an intense but informal exchange of views at the frontiers of a subject aims at identifying directions for future action.
Following a transformation of the programme in 2006 the Series has been re-named and re-organised. Recent volumes on topics not related to security, which result from meetings supported under the programme earlier, may be found in the NATO Science Series.
The Series is published by IOS Press, Amsterdam, and Springer Science and Business Media, Dordrecht, in conjunction with the NATO Emerging Security Challenges Division.
Sub-Series
A. Chemistry and Biology Springer Science and Business Media B. Physics and Biophysics Springer Science and Business Media C. Environmental Security Springer Science and Business Media D. Information and Communication Security IOS Press E. Human and Societal Dynamics IOS Press
http://www.nato.int/science http://www.springer.com http://www.iospress.nl
Sub-Series D: Information and Communication Security – Vol. 36 ISSN 1874-6268 (print) ISSN 1879-8292 (online)
5
A Weak-Memory BugAt least on the hardware I’m testing, it seems that thekey requirement for a failure to be seen is that there’s alot of contention for the cache line containing the flag,but not for the cache line containing the latch. Thisallows the write to the flag to take longer to propagateto main memory than the write to the latch. I could notget it to fail until I added the extra shared-memorytraffic in the delay loop around line 175. This probablyalso explains why it doesn’t fail with small numbers ofworkers – you need enough contending CPUs tosaturate the memory hardware. (On Red Hat’s testmachines, 7 or 8 workers would reliably fail within afew minutes, but 6 or fewer didn’t always.)
http:
//archives.postgresql.org/pgsql-hackers/2011-08/msg00330.php
(Sun, 07 Aug 2011)
D. Kroening: Weak Memory Models
NATO Science for Peace and Security Series
This Series presents the results of scientific meetings supported under the NATO Programme: Science for Peace and Security (SPS).
The NATO SPS Programme supports meetings in the following Key Priority areas: (1) Defence Against Terrorism; (2) Countering other Threats to Security and (3) NATO, Partner and Mediterranean Dialogue Country Priorities. The types of meeting supported are generally “Advanced Study Institutes” and “Advanced Research Workshops”. The NATO SPS Series collects together the results of these meetings. The meetings are co-organized by scientists from NATO countries and scientists from NATO’s “Partner” or “Mediterranean Dialogue” countries. The observations and recommendations made at the meetings, as well as the contents of the volumes in the Series, reflect those of participants and contributors only; they should not necessarily be regarded as reflecting NATO views or policy.
Advanced Study Institutes (ASI) are high-level tutorial courses to convey the latest developments in a subject to an advanced-level audience.
Advanced Research Workshops (ARW) are expert meetings where an intense but informal exchange of views at the frontiers of a subject aims at identifying directions for future action.
Following a transformation of the programme in 2006 the Series has been re-named and re-organised. Recent volumes on topics not related to security, which result from meetings supported under the programme earlier, may be found in the NATO Science Series.
The Series is published by IOS Press, Amsterdam, and Springer Science and Business Media, Dordrecht, in conjunction with the NATO Emerging Security Challenges Division.
Sub-Series
A. Chemistry and Biology Springer Science and Business Media B. Physics and Biophysics Springer Science and Business Media C. Environmental Security Springer Science and Business Media D. Information and Communication Security IOS Press E. Human and Societal Dynamics IOS Press
http://www.nato.int/science http://www.springer.com http://www.iospress.nl
Sub-Series D: Information and Communication Security – Vol. 36 ISSN 1874-6268 (print) ISSN 1879-8292 (online)
6
From the same follow up discussion:
I’m entirely convinced that we need to insert somememory-barrier instructions into the latch code beforewe expand our uses of latches much more. Since wewere already finding that memory barriers will beneeded for performance reasons elsewhere, I think it’stime to bite the bullet and develop that infrastructure.
http:
//archives.postgresql.org/pgsql-hackers/2011-08/msg00330.php
(Sun, 07 Aug 2011)
D. Kroening: Weak Memory Models
NATO Science for Peace and Security Series
This Series presents the results of scientific meetings supported under the NATO Programme: Science for Peace and Security (SPS).
The NATO SPS Programme supports meetings in the following Key Priority areas: (1) Defence Against Terrorism; (2) Countering other Threats to Security and (3) NATO, Partner and Mediterranean Dialogue Country Priorities. The types of meeting supported are generally “Advanced Study Institutes” and “Advanced Research Workshops”. The NATO SPS Series collects together the results of these meetings. The meetings are co-organized by scientists from NATO countries and scientists from NATO’s “Partner” or “Mediterranean Dialogue” countries. The observations and recommendations made at the meetings, as well as the contents of the volumes in the Series, reflect those of participants and contributors only; they should not necessarily be regarded as reflecting NATO views or policy.
Advanced Study Institutes (ASI) are high-level tutorial courses to convey the latest developments in a subject to an advanced-level audience.
Advanced Research Workshops (ARW) are expert meetings where an intense but informal exchange of views at the frontiers of a subject aims at identifying directions for future action.
Following a transformation of the programme in 2006 the Series has been re-named and re-organised. Recent volumes on topics not related to security, which result from meetings supported under the programme earlier, may be found in the NATO Science Series.
The Series is published by IOS Press, Amsterdam, and Springer Science and Business Media, Dordrecht, in conjunction with the NATO Emerging Security Challenges Division.
Sub-Series
A. Chemistry and Biology Springer Science and Business Media B. Physics and Biophysics Springer Science and Business Media C. Environmental Security Springer Science and Business Media D. Information and Communication Security IOS Press E. Human and Societal Dynamics IOS Press
http://www.nato.int/science http://www.springer.com http://www.iospress.nl
Sub-Series D: Information and Communication Security – Vol. 36 ISSN 1874-6268 (print) ISSN 1879-8292 (online)
7
First Attempt to Fix PostgreSQLImprove the documentation aroundweak-memory-ordering risks, and do a pass ofgeneral editorialization on the comments in the latchcode. Make the Windows latch code more like theUnix latch code where feasible; in particular providethe same Assert checks in both implementations. Fixpoorly-placed WaitLatch call in syncrep.c.This patch resolves, for the moment, concerns aroundweak-memory-ordering bugs in latch-related code: wehave documented the restrictions and checked thatexisting calls meet them. In 9.2 I hope that we willinstall suitable memory barrier instructions inSetLatch/ResetLatch, so that their callers don’t needto be quite so careful.
http://git.postgresql.org/gitweb/?p=postgresql.git;a=commitdiff;
h=4e15a4db5e65e43271f8d20750d6500ab12632d0 (Tue, 9 Aug 2011)
D. Kroening: Weak Memory Models
NATO Science for Peace and Security Series
This Series presents the results of scientific meetings supported under the NATO Programme: Science for Peace and Security (SPS).
The NATO SPS Programme supports meetings in the following Key Priority areas: (1) Defence Against Terrorism; (2) Countering other Threats to Security and (3) NATO, Partner and Mediterranean Dialogue Country Priorities. The types of meeting supported are generally “Advanced Study Institutes” and “Advanced Research Workshops”. The NATO SPS Series collects together the results of these meetings. The meetings are co-organized by scientists from NATO countries and scientists from NATO’s “Partner” or “Mediterranean Dialogue” countries. The observations and recommendations made at the meetings, as well as the contents of the volumes in the Series, reflect those of participants and contributors only; they should not necessarily be regarded as reflecting NATO views or policy.
Advanced Study Institutes (ASI) are high-level tutorial courses to convey the latest developments in a subject to an advanced-level audience.
Advanced Research Workshops (ARW) are expert meetings where an intense but informal exchange of views at the frontiers of a subject aims at identifying directions for future action.
Following a transformation of the programme in 2006 the Series has been re-named and re-organised. Recent volumes on topics not related to security, which result from meetings supported under the programme earlier, may be found in the NATO Science Series.
The Series is published by IOS Press, Amsterdam, and Springer Science and Business Media, Dordrecht, in conjunction with the NATO Emerging Security Challenges Division.
Sub-Series
A. Chemistry and Biology Springer Science and Business Media B. Physics and Biophysics Springer Science and Business Media C. Environmental Security Springer Science and Business Media D. Information and Communication Security IOS Press E. Human and Societal Dynamics IOS Press
http://www.nato.int/science http://www.springer.com http://www.iospress.nl
Sub-Series D: Information and Communication Security – Vol. 36 ISSN 1874-6268 (print) ISSN 1879-8292 (online)
8
This kind of problems seems to be:
I peculiar to certain types of machines (“on the hardware I’mtesting, it seems that the key requirement for a failure to beseen is that [...]”)
I difficult to reproduce (“7 or 8 workers would reliably failwithin a few minutes, but 6 or fewer didn’t always.”)
I difficult to fix (the developers’ fix consists of “improv[ing]the documentation around weak-memory-ordering risks,and do[ing] a pass of general editorialization on thecomments in the latch code.”)
D. Kroening: Weak Memory Models
NATO Science for Peace and Security Series
This Series presents the results of scientific meetings supported under the NATO Programme: Science for Peace and Security (SPS).
The NATO SPS Programme supports meetings in the following Key Priority areas: (1) Defence Against Terrorism; (2) Countering other Threats to Security and (3) NATO, Partner and Mediterranean Dialogue Country Priorities. The types of meeting supported are generally “Advanced Study Institutes” and “Advanced Research Workshops”. The NATO SPS Series collects together the results of these meetings. The meetings are co-organized by scientists from NATO countries and scientists from NATO’s “Partner” or “Mediterranean Dialogue” countries. The observations and recommendations made at the meetings, as well as the contents of the volumes in the Series, reflect those of participants and contributors only; they should not necessarily be regarded as reflecting NATO views or policy.
Advanced Study Institutes (ASI) are high-level tutorial courses to convey the latest developments in a subject to an advanced-level audience.
Advanced Research Workshops (ARW) are expert meetings where an intense but informal exchange of views at the frontiers of a subject aims at identifying directions for future action.
Following a transformation of the programme in 2006 the Series has been re-named and re-organised. Recent volumes on topics not related to security, which result from meetings supported under the programme earlier, may be found in the NATO Science Series.
The Series is published by IOS Press, Amsterdam, and Springer Science and Business Media, Dordrecht, in conjunction with the NATO Emerging Security Challenges Division.
Sub-Series
A. Chemistry and Biology Springer Science and Business Media B. Physics and Biophysics Springer Science and Business Media C. Environmental Security Springer Science and Business Media D. Information and Communication Security IOS Press E. Human and Societal Dynamics IOS Press
http://www.nato.int/science http://www.springer.com http://www.iospress.nl
Sub-Series D: Information and Communication Security – Vol. 36 ISSN 1874-6268 (print) ISSN 1879-8292 (online)
9
Example
Thread 1 Thread 2a) mov [x], 1 b) mov [y], 1
c) mov eax, [y] d) mov ebx, [x]
[x] [y]
0 0
Thread 1 Thread 2eax =
0
ebx =
1
D. Kroening: Weak Memory Models
NATO Science for Peace and Security Series
This Series presents the results of scientific meetings supported under the NATO Programme: Science for Peace and Security (SPS).
The NATO SPS Programme supports meetings in the following Key Priority areas: (1) Defence Against Terrorism; (2) Countering other Threats to Security and (3) NATO, Partner and Mediterranean Dialogue Country Priorities. The types of meeting supported are generally “Advanced Study Institutes” and “Advanced Research Workshops”. The NATO SPS Series collects together the results of these meetings. The meetings are co-organized by scientists from NATO countries and scientists from NATO’s “Partner” or “Mediterranean Dialogue” countries. The observations and recommendations made at the meetings, as well as the contents of the volumes in the Series, reflect those of participants and contributors only; they should not necessarily be regarded as reflecting NATO views or policy.
Advanced Study Institutes (ASI) are high-level tutorial courses to convey the latest developments in a subject to an advanced-level audience.
Advanced Research Workshops (ARW) are expert meetings where an intense but informal exchange of views at the frontiers of a subject aims at identifying directions for future action.
Following a transformation of the programme in 2006 the Series has been re-named and re-organised. Recent volumes on topics not related to security, which result from meetings supported under the programme earlier, may be found in the NATO Science Series.
The Series is published by IOS Press, Amsterdam, and Springer Science and Business Media, Dordrecht, in conjunction with the NATO Emerging Security Challenges Division.
Sub-Series
A. Chemistry and Biology Springer Science and Business Media B. Physics and Biophysics Springer Science and Business Media C. Environmental Security Springer Science and Business Media D. Information and Communication Security IOS Press E. Human and Societal Dynamics IOS Press
http://www.nato.int/science http://www.springer.com http://www.iospress.nl
Sub-Series D: Information and Communication Security – Vol. 36 ISSN 1874-6268 (print) ISSN 1879-8292 (online)
10
Example
Thread 1 Thread 2a) mov [x], 1 b) mov [y], 1
c) mov eax, [y] d) mov ebx, [x]
[x] [y]
0 0
Thread 1 Thread 2eax =
0
ebx =
1
D. Kroening: Weak Memory Models
NATO Science for Peace and Security Series
This Series presents the results of scientific meetings supported under the NATO Programme: Science for Peace and Security (SPS).
The NATO SPS Programme supports meetings in the following Key Priority areas: (1) Defence Against Terrorism; (2) Countering other Threats to Security and (3) NATO, Partner and Mediterranean Dialogue Country Priorities. The types of meeting supported are generally “Advanced Study Institutes” and “Advanced Research Workshops”. The NATO SPS Series collects together the results of these meetings. The meetings are co-organized by scientists from NATO countries and scientists from NATO’s “Partner” or “Mediterranean Dialogue” countries. The observations and recommendations made at the meetings, as well as the contents of the volumes in the Series, reflect those of participants and contributors only; they should not necessarily be regarded as reflecting NATO views or policy.
Advanced Study Institutes (ASI) are high-level tutorial courses to convey the latest developments in a subject to an advanced-level audience.
Advanced Research Workshops (ARW) are expert meetings where an intense but informal exchange of views at the frontiers of a subject aims at identifying directions for future action.
Following a transformation of the programme in 2006 the Series has been re-named and re-organised. Recent volumes on topics not related to security, which result from meetings supported under the programme earlier, may be found in the NATO Science Series.
The Series is published by IOS Press, Amsterdam, and Springer Science and Business Media, Dordrecht, in conjunction with the NATO Emerging Security Challenges Division.
Sub-Series
A. Chemistry and Biology Springer Science and Business Media B. Physics and Biophysics Springer Science and Business Media C. Environmental Security Springer Science and Business Media D. Information and Communication Security IOS Press E. Human and Societal Dynamics IOS Press
http://www.nato.int/science http://www.springer.com http://www.iospress.nl
Sub-Series D: Information and Communication Security – Vol. 36 ISSN 1874-6268 (print) ISSN 1879-8292 (online)
10
Example
Thread 1 Thread 2a) mov [x], 1 b) mov [y], 1
c) mov eax, [y] d) mov ebx, [x]
[x] [y]
1 0
Thread 1 Thread 2eax =
0
ebx =
1
D. Kroening: Weak Memory Models
NATO Science for Peace and Security Series
This Series presents the results of scientific meetings supported under the NATO Programme: Science for Peace and Security (SPS).
The NATO SPS Programme supports meetings in the following Key Priority areas: (1) Defence Against Terrorism; (2) Countering other Threats to Security and (3) NATO, Partner and Mediterranean Dialogue Country Priorities. The types of meeting supported are generally “Advanced Study Institutes” and “Advanced Research Workshops”. The NATO SPS Series collects together the results of these meetings. The meetings are co-organized by scientists from NATO countries and scientists from NATO’s “Partner” or “Mediterranean Dialogue” countries. The observations and recommendations made at the meetings, as well as the contents of the volumes in the Series, reflect those of participants and contributors only; they should not necessarily be regarded as reflecting NATO views or policy.
Advanced Study Institutes (ASI) are high-level tutorial courses to convey the latest developments in a subject to an advanced-level audience.
Advanced Research Workshops (ARW) are expert meetings where an intense but informal exchange of views at the frontiers of a subject aims at identifying directions for future action.
Following a transformation of the programme in 2006 the Series has been re-named and re-organised. Recent volumes on topics not related to security, which result from meetings supported under the programme earlier, may be found in the NATO Science Series.
The Series is published by IOS Press, Amsterdam, and Springer Science and Business Media, Dordrecht, in conjunction with the NATO Emerging Security Challenges Division.
Sub-Series
A. Chemistry and Biology Springer Science and Business Media B. Physics and Biophysics Springer Science and Business Media C. Environmental Security Springer Science and Business Media D. Information and Communication Security IOS Press E. Human and Societal Dynamics IOS Press
http://www.nato.int/science http://www.springer.com http://www.iospress.nl
Sub-Series D: Information and Communication Security – Vol. 36 ISSN 1874-6268 (print) ISSN 1879-8292 (online)
10
Example
Thread 1 Thread 2a) mov [x], 1 b) mov [y], 1
c) mov eax, [y] d) mov ebx, [x]
[x] [y]
1 0
Thread 1 Thread 2eax = 0 ebx =
1
D. Kroening: Weak Memory Models
NATO Science for Peace and Security Series
This Series presents the results of scientific meetings supported under the NATO Programme: Science for Peace and Security (SPS).
The NATO SPS Programme supports meetings in the following Key Priority areas: (1) Defence Against Terrorism; (2) Countering other Threats to Security and (3) NATO, Partner and Mediterranean Dialogue Country Priorities. The types of meeting supported are generally “Advanced Study Institutes” and “Advanced Research Workshops”. The NATO SPS Series collects together the results of these meetings. The meetings are co-organized by scientists from NATO countries and scientists from NATO’s “Partner” or “Mediterranean Dialogue” countries. The observations and recommendations made at the meetings, as well as the contents of the volumes in the Series, reflect those of participants and contributors only; they should not necessarily be regarded as reflecting NATO views or policy.
Advanced Study Institutes (ASI) are high-level tutorial courses to convey the latest developments in a subject to an advanced-level audience.
Advanced Research Workshops (ARW) are expert meetings where an intense but informal exchange of views at the frontiers of a subject aims at identifying directions for future action.
Following a transformation of the programme in 2006 the Series has been re-named and re-organised. Recent volumes on topics not related to security, which result from meetings supported under the programme earlier, may be found in the NATO Science Series.
The Series is published by IOS Press, Amsterdam, and Springer Science and Business Media, Dordrecht, in conjunction with the NATO Emerging Security Challenges Division.
Sub-Series
A. Chemistry and Biology Springer Science and Business Media B. Physics and Biophysics Springer Science and Business Media C. Environmental Security Springer Science and Business Media D. Information and Communication Security IOS Press E. Human and Societal Dynamics IOS Press
http://www.nato.int/science http://www.springer.com http://www.iospress.nl
Sub-Series D: Information and Communication Security – Vol. 36 ISSN 1874-6268 (print) ISSN 1879-8292 (online)
10
Example
Thread 1 Thread 2a) mov [x], 1 b) mov [y], 1
c) mov eax, [y] d) mov ebx, [x]
[x] [y]
1 1
Thread 1 Thread 2eax = 0 ebx =
1
D. Kroening: Weak Memory Models
NATO Science for Peace and Security Series
This Series presents the results of scientific meetings supported under the NATO Programme: Science for Peace and Security (SPS).
The NATO SPS Programme supports meetings in the following Key Priority areas: (1) Defence Against Terrorism; (2) Countering other Threats to Security and (3) NATO, Partner and Mediterranean Dialogue Country Priorities. The types of meeting supported are generally “Advanced Study Institutes” and “Advanced Research Workshops”. The NATO SPS Series collects together the results of these meetings. The meetings are co-organized by scientists from NATO countries and scientists from NATO’s “Partner” or “Mediterranean Dialogue” countries. The observations and recommendations made at the meetings, as well as the contents of the volumes in the Series, reflect those of participants and contributors only; they should not necessarily be regarded as reflecting NATO views or policy.
Advanced Study Institutes (ASI) are high-level tutorial courses to convey the latest developments in a subject to an advanced-level audience.
Advanced Research Workshops (ARW) are expert meetings where an intense but informal exchange of views at the frontiers of a subject aims at identifying directions for future action.
Following a transformation of the programme in 2006 the Series has been re-named and re-organised. Recent volumes on topics not related to security, which result from meetings supported under the programme earlier, may be found in the NATO Science Series.
The Series is published by IOS Press, Amsterdam, and Springer Science and Business Media, Dordrecht, in conjunction with the NATO Emerging Security Challenges Division.
Sub-Series
A. Chemistry and Biology Springer Science and Business Media B. Physics and Biophysics Springer Science and Business Media C. Environmental Security Springer Science and Business Media D. Information and Communication Security IOS Press E. Human and Societal Dynamics IOS Press
http://www.nato.int/science http://www.springer.com http://www.iospress.nl
Sub-Series D: Information and Communication Security – Vol. 36 ISSN 1874-6268 (print) ISSN 1879-8292 (online)
10
Example
Thread 1 Thread 2a) mov [x], 1 b) mov [y], 1
c) mov eax, [y] d) mov ebx, [x]
[x] [y]
1 1
Thread 1 Thread 2eax = 0 ebx = 1
D. Kroening: Weak Memory Models
NATO Science for Peace and Security Series
This Series presents the results of scientific meetings supported under the NATO Programme: Science for Peace and Security (SPS).
The NATO SPS Programme supports meetings in the following Key Priority areas: (1) Defence Against Terrorism; (2) Countering other Threats to Security and (3) NATO, Partner and Mediterranean Dialogue Country Priorities. The types of meeting supported are generally “Advanced Study Institutes” and “Advanced Research Workshops”. The NATO SPS Series collects together the results of these meetings. The meetings are co-organized by scientists from NATO countries and scientists from NATO’s “Partner” or “Mediterranean Dialogue” countries. The observations and recommendations made at the meetings, as well as the contents of the volumes in the Series, reflect those of participants and contributors only; they should not necessarily be regarded as reflecting NATO views or policy.
Advanced Study Institutes (ASI) are high-level tutorial courses to convey the latest developments in a subject to an advanced-level audience.
Advanced Research Workshops (ARW) are expert meetings where an intense but informal exchange of views at the frontiers of a subject aims at identifying directions for future action.
Following a transformation of the programme in 2006 the Series has been re-named and re-organised. Recent volumes on topics not related to security, which result from meetings supported under the programme earlier, may be found in the NATO Science Series.
The Series is published by IOS Press, Amsterdam, and Springer Science and Business Media, Dordrecht, in conjunction with the NATO Emerging Security Challenges Division.
Sub-Series
A. Chemistry and Biology Springer Science and Business Media B. Physics and Biophysics Springer Science and Business Media C. Environmental Security Springer Science and Business Media D. Information and Communication Security IOS Press E. Human and Societal Dynamics IOS Press
http://www.nato.int/science http://www.springer.com http://www.iospress.nl
Sub-Series D: Information and Communication Security – Vol. 36 ISSN 1874-6268 (print) ISSN 1879-8292 (online)
10
We expect three possible outcomes:
Ordering eax ebx(a)(b)(c)(d) 0 1(c)(d)(a)(b) 1 0(a)(c)(b)(d) 1 1(a)(c)(d)(b)(c)(a)(b)(d)(c)(a)(d)(b)
D. Kroening: Weak Memory Models
NATO Science for Peace and Security Series
This Series presents the results of scientific meetings supported under the NATO Programme: Science for Peace and Security (SPS).
The NATO SPS Programme supports meetings in the following Key Priority areas: (1) Defence Against Terrorism; (2) Countering other Threats to Security and (3) NATO, Partner and Mediterranean Dialogue Country Priorities. The types of meeting supported are generally “Advanced Study Institutes” and “Advanced Research Workshops”. The NATO SPS Series collects together the results of these meetings. The meetings are co-organized by scientists from NATO countries and scientists from NATO’s “Partner” or “Mediterranean Dialogue” countries. The observations and recommendations made at the meetings, as well as the contents of the volumes in the Series, reflect those of participants and contributors only; they should not necessarily be regarded as reflecting NATO views or policy.
Advanced Study Institutes (ASI) are high-level tutorial courses to convey the latest developments in a subject to an advanced-level audience.
Advanced Research Workshops (ARW) are expert meetings where an intense but informal exchange of views at the frontiers of a subject aims at identifying directions for future action.
Following a transformation of the programme in 2006 the Series has been re-named and re-organised. Recent volumes on topics not related to security, which result from meetings supported under the programme earlier, may be found in the NATO Science Series.
The Series is published by IOS Press, Amsterdam, and Springer Science and Business Media, Dordrecht, in conjunction with the NATO Emerging Security Challenges Division.
Sub-Series
A. Chemistry and Biology Springer Science and Business Media B. Physics and Biophysics Springer Science and Business Media C. Environmental Security Springer Science and Business Media D. Information and Communication Security IOS Press E. Human and Societal Dynamics IOS Press
http://www.nato.int/science http://www.springer.com http://www.iospress.nl
Sub-Series D: Information and Communication Security – Vol. 36 ISSN 1874-6268 (print) ISSN 1879-8292 (online)
11
Histogram for 1 million runs:
EAX=0, EBX=0
34
EAX=1, EBX=0
499911
EAX=0, EBX=1
499805
EAX=1, EBX=1
250
Unfortunately, the program may terminate with eax=ebx=0!
D. Kroening: Weak Memory Models
NATO Science for Peace and Security Series
This Series presents the results of scientific meetings supported under the NATO Programme: Science for Peace and Security (SPS).
The NATO SPS Programme supports meetings in the following Key Priority areas: (1) Defence Against Terrorism; (2) Countering other Threats to Security and (3) NATO, Partner and Mediterranean Dialogue Country Priorities. The types of meeting supported are generally “Advanced Study Institutes” and “Advanced Research Workshops”. The NATO SPS Series collects together the results of these meetings. The meetings are co-organized by scientists from NATO countries and scientists from NATO’s “Partner” or “Mediterranean Dialogue” countries. The observations and recommendations made at the meetings, as well as the contents of the volumes in the Series, reflect those of participants and contributors only; they should not necessarily be regarded as reflecting NATO views or policy.
Advanced Study Institutes (ASI) are high-level tutorial courses to convey the latest developments in a subject to an advanced-level audience.
Advanced Research Workshops (ARW) are expert meetings where an intense but informal exchange of views at the frontiers of a subject aims at identifying directions for future action.
Following a transformation of the programme in 2006 the Series has been re-named and re-organised. Recent volumes on topics not related to security, which result from meetings supported under the programme earlier, may be found in the NATO Science Series.
The Series is published by IOS Press, Amsterdam, and Springer Science and Business Media, Dordrecht, in conjunction with the NATO Emerging Security Challenges Division.
Sub-Series
A. Chemistry and Biology Springer Science and Business Media B. Physics and Biophysics Springer Science and Business Media C. Environmental Security Springer Science and Business Media D. Information and Communication Security IOS Press E. Human and Societal Dynamics IOS Press
http://www.nato.int/science http://www.springer.com http://www.iospress.nl
Sub-Series D: Information and Communication Security – Vol. 36 ISSN 1874-6268 (print) ISSN 1879-8292 (online)
12
Store Buffering
Thread 1 Thread 2a) mov [x], 1 b) mov [y], 1
c) mov eax, [y] d) mov ebx, [x]
[x] [y] [BUFFx]
0 0
Thread 1 Thread 2eax =
0
ebx =
0
D. Kroening: Weak Memory Models
NATO Science for Peace and Security Series
This Series presents the results of scientific meetings supported under the NATO Programme: Science for Peace and Security (SPS).
The NATO SPS Programme supports meetings in the following Key Priority areas: (1) Defence Against Terrorism; (2) Countering other Threats to Security and (3) NATO, Partner and Mediterranean Dialogue Country Priorities. The types of meeting supported are generally “Advanced Study Institutes” and “Advanced Research Workshops”. The NATO SPS Series collects together the results of these meetings. The meetings are co-organized by scientists from NATO countries and scientists from NATO’s “Partner” or “Mediterranean Dialogue” countries. The observations and recommendations made at the meetings, as well as the contents of the volumes in the Series, reflect those of participants and contributors only; they should not necessarily be regarded as reflecting NATO views or policy.
Advanced Study Institutes (ASI) are high-level tutorial courses to convey the latest developments in a subject to an advanced-level audience.
Advanced Research Workshops (ARW) are expert meetings where an intense but informal exchange of views at the frontiers of a subject aims at identifying directions for future action.
Following a transformation of the programme in 2006 the Series has been re-named and re-organised. Recent volumes on topics not related to security, which result from meetings supported under the programme earlier, may be found in the NATO Science Series.
The Series is published by IOS Press, Amsterdam, and Springer Science and Business Media, Dordrecht, in conjunction with the NATO Emerging Security Challenges Division.
Sub-Series
A. Chemistry and Biology Springer Science and Business Media B. Physics and Biophysics Springer Science and Business Media C. Environmental Security Springer Science and Business Media D. Information and Communication Security IOS Press E. Human and Societal Dynamics IOS Press
http://www.nato.int/science http://www.springer.com http://www.iospress.nl
Sub-Series D: Information and Communication Security – Vol. 36 ISSN 1874-6268 (print) ISSN 1879-8292 (online)
13
Store Buffering
Thread 1 Thread 2a) mov [x], 1 b) mov [y], 1
c) mov eax, [y] d) mov ebx, [x]
[x] [y] [BUFFx]
0 0
Thread 1 Thread 2eax =
0
ebx =
0
D. Kroening: Weak Memory Models
NATO Science for Peace and Security Series
This Series presents the results of scientific meetings supported under the NATO Programme: Science for Peace and Security (SPS).
The NATO SPS Programme supports meetings in the following Key Priority areas: (1) Defence Against Terrorism; (2) Countering other Threats to Security and (3) NATO, Partner and Mediterranean Dialogue Country Priorities. The types of meeting supported are generally “Advanced Study Institutes” and “Advanced Research Workshops”. The NATO SPS Series collects together the results of these meetings. The meetings are co-organized by scientists from NATO countries and scientists from NATO’s “Partner” or “Mediterranean Dialogue” countries. The observations and recommendations made at the meetings, as well as the contents of the volumes in the Series, reflect those of participants and contributors only; they should not necessarily be regarded as reflecting NATO views or policy.
Advanced Study Institutes (ASI) are high-level tutorial courses to convey the latest developments in a subject to an advanced-level audience.
Advanced Research Workshops (ARW) are expert meetings where an intense but informal exchange of views at the frontiers of a subject aims at identifying directions for future action.
Following a transformation of the programme in 2006 the Series has been re-named and re-organised. Recent volumes on topics not related to security, which result from meetings supported under the programme earlier, may be found in the NATO Science Series.
The Series is published by IOS Press, Amsterdam, and Springer Science and Business Media, Dordrecht, in conjunction with the NATO Emerging Security Challenges Division.
Sub-Series
A. Chemistry and Biology Springer Science and Business Media B. Physics and Biophysics Springer Science and Business Media C. Environmental Security Springer Science and Business Media D. Information and Communication Security IOS Press E. Human and Societal Dynamics IOS Press
http://www.nato.int/science http://www.springer.com http://www.iospress.nl
Sub-Series D: Information and Communication Security – Vol. 36 ISSN 1874-6268 (print) ISSN 1879-8292 (online)
13
Store Buffering
Thread 1 Thread 2a) mov [x], 1 b) mov [y], 1
c) mov eax, [y] d) mov ebx, [x]
[x] [y] [BUFFx]
0 0 1
Thread 1 Thread 2eax =
0
ebx =
0
D. Kroening: Weak Memory Models
NATO Science for Peace and Security Series
This Series presents the results of scientific meetings supported under the NATO Programme: Science for Peace and Security (SPS).
The NATO SPS Programme supports meetings in the following Key Priority areas: (1) Defence Against Terrorism; (2) Countering other Threats to Security and (3) NATO, Partner and Mediterranean Dialogue Country Priorities. The types of meeting supported are generally “Advanced Study Institutes” and “Advanced Research Workshops”. The NATO SPS Series collects together the results of these meetings. The meetings are co-organized by scientists from NATO countries and scientists from NATO’s “Partner” or “Mediterranean Dialogue” countries. The observations and recommendations made at the meetings, as well as the contents of the volumes in the Series, reflect those of participants and contributors only; they should not necessarily be regarded as reflecting NATO views or policy.
Advanced Study Institutes (ASI) are high-level tutorial courses to convey the latest developments in a subject to an advanced-level audience.
Advanced Research Workshops (ARW) are expert meetings where an intense but informal exchange of views at the frontiers of a subject aims at identifying directions for future action.
Following a transformation of the programme in 2006 the Series has been re-named and re-organised. Recent volumes on topics not related to security, which result from meetings supported under the programme earlier, may be found in the NATO Science Series.
The Series is published by IOS Press, Amsterdam, and Springer Science and Business Media, Dordrecht, in conjunction with the NATO Emerging Security Challenges Division.
Sub-Series
A. Chemistry and Biology Springer Science and Business Media B. Physics and Biophysics Springer Science and Business Media C. Environmental Security Springer Science and Business Media D. Information and Communication Security IOS Press E. Human and Societal Dynamics IOS Press
http://www.nato.int/science http://www.springer.com http://www.iospress.nl
Sub-Series D: Information and Communication Security – Vol. 36 ISSN 1874-6268 (print) ISSN 1879-8292 (online)
13
Store Buffering
Thread 1 Thread 2a) mov [x], 1 b) mov [y], 1
c) mov eax, [y] d) mov ebx, [x]
[x] [y] [BUFFx]
0 0 1
Thread 1 Thread 2eax = 0 ebx =
0
D. Kroening: Weak Memory Models
NATO Science for Peace and Security Series
This Series presents the results of scientific meetings supported under the NATO Programme: Science for Peace and Security (SPS).
The NATO SPS Programme supports meetings in the following Key Priority areas: (1) Defence Against Terrorism; (2) Countering other Threats to Security and (3) NATO, Partner and Mediterranean Dialogue Country Priorities. The types of meeting supported are generally “Advanced Study Institutes” and “Advanced Research Workshops”. The NATO SPS Series collects together the results of these meetings. The meetings are co-organized by scientists from NATO countries and scientists from NATO’s “Partner” or “Mediterranean Dialogue” countries. The observations and recommendations made at the meetings, as well as the contents of the volumes in the Series, reflect those of participants and contributors only; they should not necessarily be regarded as reflecting NATO views or policy.
Advanced Study Institutes (ASI) are high-level tutorial courses to convey the latest developments in a subject to an advanced-level audience.
Advanced Research Workshops (ARW) are expert meetings where an intense but informal exchange of views at the frontiers of a subject aims at identifying directions for future action.
Following a transformation of the programme in 2006 the Series has been re-named and re-organised. Recent volumes on topics not related to security, which result from meetings supported under the programme earlier, may be found in the NATO Science Series.
The Series is published by IOS Press, Amsterdam, and Springer Science and Business Media, Dordrecht, in conjunction with the NATO Emerging Security Challenges Division.
Sub-Series
A. Chemistry and Biology Springer Science and Business Media B. Physics and Biophysics Springer Science and Business Media C. Environmental Security Springer Science and Business Media D. Information and Communication Security IOS Press E. Human and Societal Dynamics IOS Press
http://www.nato.int/science http://www.springer.com http://www.iospress.nl
Sub-Series D: Information and Communication Security – Vol. 36 ISSN 1874-6268 (print) ISSN 1879-8292 (online)
13
Store Buffering
Thread 1 Thread 2a) mov [x], 1 b) mov [y], 1
c) mov eax, [y] d) mov ebx, [x]
[x] [y] [BUFFx]
0 1 1
Thread 1 Thread 2eax = 0 ebx =
0
D. Kroening: Weak Memory Models
NATO Science for Peace and Security Series
This Series presents the results of scientific meetings supported under the NATO Programme: Science for Peace and Security (SPS).
The NATO SPS Programme supports meetings in the following Key Priority areas: (1) Defence Against Terrorism; (2) Countering other Threats to Security and (3) NATO, Partner and Mediterranean Dialogue Country Priorities. The types of meeting supported are generally “Advanced Study Institutes” and “Advanced Research Workshops”. The NATO SPS Series collects together the results of these meetings. The meetings are co-organized by scientists from NATO countries and scientists from NATO’s “Partner” or “Mediterranean Dialogue” countries. The observations and recommendations made at the meetings, as well as the contents of the volumes in the Series, reflect those of participants and contributors only; they should not necessarily be regarded as reflecting NATO views or policy.
Advanced Study Institutes (ASI) are high-level tutorial courses to convey the latest developments in a subject to an advanced-level audience.
Advanced Research Workshops (ARW) are expert meetings where an intense but informal exchange of views at the frontiers of a subject aims at identifying directions for future action.
Following a transformation of the programme in 2006 the Series has been re-named and re-organised. Recent volumes on topics not related to security, which result from meetings supported under the programme earlier, may be found in the NATO Science Series.
The Series is published by IOS Press, Amsterdam, and Springer Science and Business Media, Dordrecht, in conjunction with the NATO Emerging Security Challenges Division.
Sub-Series
A. Chemistry and Biology Springer Science and Business Media B. Physics and Biophysics Springer Science and Business Media C. Environmental Security Springer Science and Business Media D. Information and Communication Security IOS Press E. Human and Societal Dynamics IOS Press
http://www.nato.int/science http://www.springer.com http://www.iospress.nl
Sub-Series D: Information and Communication Security – Vol. 36 ISSN 1874-6268 (print) ISSN 1879-8292 (online)
13
Store Buffering
Thread 1 Thread 2a) mov [x], 1 b) mov [y], 1
c) mov eax, [y] d) mov ebx, [x]
[x] [y] [BUFFx]
0 1 1
Thread 1 Thread 2eax = 0 ebx = 0
D. Kroening: Weak Memory Models
NATO Science for Peace and Security Series
This Series presents the results of scientific meetings supported under the NATO Programme: Science for Peace and Security (SPS).
The NATO SPS Programme supports meetings in the following Key Priority areas: (1) Defence Against Terrorism; (2) Countering other Threats to Security and (3) NATO, Partner and Mediterranean Dialogue Country Priorities. The types of meeting supported are generally “Advanced Study Institutes” and “Advanced Research Workshops”. The NATO SPS Series collects together the results of these meetings. The meetings are co-organized by scientists from NATO countries and scientists from NATO’s “Partner” or “Mediterranean Dialogue” countries. The observations and recommendations made at the meetings, as well as the contents of the volumes in the Series, reflect those of participants and contributors only; they should not necessarily be regarded as reflecting NATO views or policy.
Advanced Study Institutes (ASI) are high-level tutorial courses to convey the latest developments in a subject to an advanced-level audience.
Advanced Research Workshops (ARW) are expert meetings where an intense but informal exchange of views at the frontiers of a subject aims at identifying directions for future action.
Following a transformation of the programme in 2006 the Series has been re-named and re-organised. Recent volumes on topics not related to security, which result from meetings supported under the programme earlier, may be found in the NATO Science Series.
The Series is published by IOS Press, Amsterdam, and Springer Science and Business Media, Dordrecht, in conjunction with the NATO Emerging Security Challenges Division.
Sub-Series
A. Chemistry and Biology Springer Science and Business Media B. Physics and Biophysics Springer Science and Business Media C. Environmental Security Springer Science and Business Media D. Information and Communication Security IOS Press E. Human and Societal Dynamics IOS Press
http://www.nato.int/science http://www.springer.com http://www.iospress.nl
Sub-Series D: Information and Communication Security – Vol. 36 ISSN 1874-6268 (print) ISSN 1879-8292 (online)
13
Store Buffering
Thread 1 Thread 2a) mov [x], 1 b) mov [y], 1
c) mov eax, [y] d) mov ebx, [x]
[x] [y] [BUFFx]
1 1 flushed
Thread 1 Thread 2eax = 0 ebx = 0
D. Kroening: Weak Memory Models
NATO Science for Peace and Security Series
This Series presents the results of scientific meetings supported under the NATO Programme: Science for Peace and Security (SPS).
The NATO SPS Programme supports meetings in the following Key Priority areas: (1) Defence Against Terrorism; (2) Countering other Threats to Security and (3) NATO, Partner and Mediterranean Dialogue Country Priorities. The types of meeting supported are generally “Advanced Study Institutes” and “Advanced Research Workshops”. The NATO SPS Series collects together the results of these meetings. The meetings are co-organized by scientists from NATO countries and scientists from NATO’s “Partner” or “Mediterranean Dialogue” countries. The observations and recommendations made at the meetings, as well as the contents of the volumes in the Series, reflect those of participants and contributors only; they should not necessarily be regarded as reflecting NATO views or policy.
Advanced Study Institutes (ASI) are high-level tutorial courses to convey the latest developments in a subject to an advanced-level audience.
Advanced Research Workshops (ARW) are expert meetings where an intense but informal exchange of views at the frontiers of a subject aims at identifying directions for future action.
Following a transformation of the programme in 2006 the Series has been re-named and re-organised. Recent volumes on topics not related to security, which result from meetings supported under the programme earlier, may be found in the NATO Science Series.
The Series is published by IOS Press, Amsterdam, and Springer Science and Business Media, Dordrecht, in conjunction with the NATO Emerging Security Challenges Division.
Sub-Series
A. Chemistry and Biology Springer Science and Business Media B. Physics and Biophysics Springer Science and Business Media C. Environmental Security Springer Science and Business Media D. Information and Communication Security IOS Press E. Human and Societal Dynamics IOS Press
http://www.nato.int/science http://www.springer.com http://www.iospress.nl
Sub-Series D: Information and Communication Security – Vol. 36 ISSN 1874-6268 (print) ISSN 1879-8292 (online)
13
Weak Memory Models
I There are other effects, e.g.,prefeching, cache hierarchy
I Weak memory models describe the weakenings comparedto SC
I Well-known: TSO (x86), PSO, RMO, Power/ARM
I Often no formal link to hardware
D. Kroening: Weak Memory Models
NATO Science for Peace and Security Series
This Series presents the results of scientific meetings supported under the NATO Programme: Science for Peace and Security (SPS).
The NATO SPS Programme supports meetings in the following Key Priority areas: (1) Defence Against Terrorism; (2) Countering other Threats to Security and (3) NATO, Partner and Mediterranean Dialogue Country Priorities. The types of meeting supported are generally “Advanced Study Institutes” and “Advanced Research Workshops”. The NATO SPS Series collects together the results of these meetings. The meetings are co-organized by scientists from NATO countries and scientists from NATO’s “Partner” or “Mediterranean Dialogue” countries. The observations and recommendations made at the meetings, as well as the contents of the volumes in the Series, reflect those of participants and contributors only; they should not necessarily be regarded as reflecting NATO views or policy.
Advanced Study Institutes (ASI) are high-level tutorial courses to convey the latest developments in a subject to an advanced-level audience.
Advanced Research Workshops (ARW) are expert meetings where an intense but informal exchange of views at the frontiers of a subject aims at identifying directions for future action.
Following a transformation of the programme in 2006 the Series has been re-named and re-organised. Recent volumes on topics not related to security, which result from meetings supported under the programme earlier, may be found in the NATO Science Series.
The Series is published by IOS Press, Amsterdam, and Springer Science and Business Media, Dordrecht, in conjunction with the NATO Emerging Security Challenges Division.
Sub-Series
A. Chemistry and Biology Springer Science and Business Media B. Physics and Biophysics Springer Science and Business Media C. Environmental Security Springer Science and Business Media D. Information and Communication Security IOS Press E. Human and Societal Dynamics IOS Press
http://www.nato.int/science http://www.springer.com http://www.iospress.nl
Sub-Series D: Information and Communication Security – Vol. 36 ISSN 1874-6268 (print) ISSN 1879-8292 (online)
14
TSO, PSO, RMO
TSO: allows a read to be reordered before a writeto different address
PSO: allows a read or write to be reordered before a writeto different address
RMO: allows a read or write to be reordered before aread or write to different address
(Remark: Power/ARM cannot be modelled in this way.)
D. Kroening: Weak Memory Models
NATO Science for Peace and Security Series
This Series presents the results of scientific meetings supported under the NATO Programme: Science for Peace and Security (SPS).
The NATO SPS Programme supports meetings in the following Key Priority areas: (1) Defence Against Terrorism; (2) Countering other Threats to Security and (3) NATO, Partner and Mediterranean Dialogue Country Priorities. The types of meeting supported are generally “Advanced Study Institutes” and “Advanced Research Workshops”. The NATO SPS Series collects together the results of these meetings. The meetings are co-organized by scientists from NATO countries and scientists from NATO’s “Partner” or “Mediterranean Dialogue” countries. The observations and recommendations made at the meetings, as well as the contents of the volumes in the Series, reflect those of participants and contributors only; they should not necessarily be regarded as reflecting NATO views or policy.
Advanced Study Institutes (ASI) are high-level tutorial courses to convey the latest developments in a subject to an advanced-level audience.
Advanced Research Workshops (ARW) are expert meetings where an intense but informal exchange of views at the frontiers of a subject aims at identifying directions for future action.
Following a transformation of the programme in 2006 the Series has been re-named and re-organised. Recent volumes on topics not related to security, which result from meetings supported under the programme earlier, may be found in the NATO Science Series.
The Series is published by IOS Press, Amsterdam, and Springer Science and Business Media, Dordrecht, in conjunction with the NATO Emerging Security Challenges Division.
Sub-Series
A. Chemistry and Biology Springer Science and Business Media B. Physics and Biophysics Springer Science and Business Media C. Environmental Security Springer Science and Business Media D. Information and Communication Security IOS Press E. Human and Societal Dynamics IOS Press
http://www.nato.int/science http://www.springer.com http://www.iospress.nl
Sub-Series D: Information and Communication Security – Vol. 36 ISSN 1874-6268 (print) ISSN 1879-8292 (online)
15
Verifying Weak Memory with BMC
It’s really easy!
We just drop the constraints for thein-thread program-order!
D. Kroening: Weak Memory Models
NATO Science for Peace and Security Series
This Series presents the results of scientific meetings supported under the NATO Programme: Science for Peace and Security (SPS).
The NATO SPS Programme supports meetings in the following Key Priority areas: (1) Defence Against Terrorism; (2) Countering other Threats to Security and (3) NATO, Partner and Mediterranean Dialogue Country Priorities. The types of meeting supported are generally “Advanced Study Institutes” and “Advanced Research Workshops”. The NATO SPS Series collects together the results of these meetings. The meetings are co-organized by scientists from NATO countries and scientists from NATO’s “Partner” or “Mediterranean Dialogue” countries. The observations and recommendations made at the meetings, as well as the contents of the volumes in the Series, reflect those of participants and contributors only; they should not necessarily be regarded as reflecting NATO views or policy.
Advanced Study Institutes (ASI) are high-level tutorial courses to convey the latest developments in a subject to an advanced-level audience.
Advanced Research Workshops (ARW) are expert meetings where an intense but informal exchange of views at the frontiers of a subject aims at identifying directions for future action.
Following a transformation of the programme in 2006 the Series has been re-named and re-organised. Recent volumes on topics not related to security, which result from meetings supported under the programme earlier, may be found in the NATO Science Series.
The Series is published by IOS Press, Amsterdam, and Springer Science and Business Media, Dordrecht, in conjunction with the NATO Emerging Security Challenges Division.
Sub-Series
A. Chemistry and Biology Springer Science and Business Media B. Physics and Biophysics Springer Science and Business Media C. Environmental Security Springer Science and Business Media D. Information and Communication Security IOS Press E. Human and Societal Dynamics IOS Press
http://www.nato.int/science http://www.springer.com http://www.iospress.nl
Sub-Series D: Information and Communication Security – Vol. 36 ISSN 1874-6268 (print) ISSN 1879-8292 (online)
16
Verifying Weak Memory with BMC
It’s really easy!
We just drop the constraints for thein-thread program-order!
D. Kroening: Weak Memory Models
NATO Science for Peace and Security Series
This Series presents the results of scientific meetings supported under the NATO Programme: Science for Peace and Security (SPS).
The NATO SPS Programme supports meetings in the following Key Priority areas: (1) Defence Against Terrorism; (2) Countering other Threats to Security and (3) NATO, Partner and Mediterranean Dialogue Country Priorities. The types of meeting supported are generally “Advanced Study Institutes” and “Advanced Research Workshops”. The NATO SPS Series collects together the results of these meetings. The meetings are co-organized by scientists from NATO countries and scientists from NATO’s “Partner” or “Mediterranean Dialogue” countries. The observations and recommendations made at the meetings, as well as the contents of the volumes in the Series, reflect those of participants and contributors only; they should not necessarily be regarded as reflecting NATO views or policy.
Advanced Study Institutes (ASI) are high-level tutorial courses to convey the latest developments in a subject to an advanced-level audience.
Advanced Research Workshops (ARW) are expert meetings where an intense but informal exchange of views at the frontiers of a subject aims at identifying directions for future action.
Following a transformation of the programme in 2006 the Series has been re-named and re-organised. Recent volumes on topics not related to security, which result from meetings supported under the programme earlier, may be found in the NATO Science Series.
The Series is published by IOS Press, Amsterdam, and Springer Science and Business Media, Dordrecht, in conjunction with the NATO Emerging Security Challenges Division.
Sub-Series
A. Chemistry and Biology Springer Science and Business Media B. Physics and Biophysics Springer Science and Business Media C. Environmental Security Springer Science and Business Media D. Information and Communication Security IOS Press E. Human and Societal Dynamics IOS Press
http://www.nato.int/science http://www.springer.com http://www.iospress.nl
Sub-Series D: Information and Communication Security – Vol. 36 ISSN 1874-6268 (print) ISSN 1879-8292 (online)
16
Experimental Results
There is no other wmm-aware model checker that takes ourbenchmarks!
Real-world case-studies:I PostgreSQL (database server)I Read-Copy-Update (RCU), Linux kernelI Apache httpd (web server)
D. Kroening: Weak Memory Models
NATO Science for Peace and Security Series
This Series presents the results of scientific meetings supported under the NATO Programme: Science for Peace and Security (SPS).
The NATO SPS Programme supports meetings in the following Key Priority areas: (1) Defence Against Terrorism; (2) Countering other Threats to Security and (3) NATO, Partner and Mediterranean Dialogue Country Priorities. The types of meeting supported are generally “Advanced Study Institutes” and “Advanced Research Workshops”. The NATO SPS Series collects together the results of these meetings. The meetings are co-organized by scientists from NATO countries and scientists from NATO’s “Partner” or “Mediterranean Dialogue” countries. The observations and recommendations made at the meetings, as well as the contents of the volumes in the Series, reflect those of participants and contributors only; they should not necessarily be regarded as reflecting NATO views or policy.
Advanced Study Institutes (ASI) are high-level tutorial courses to convey the latest developments in a subject to an advanced-level audience.
Advanced Research Workshops (ARW) are expert meetings where an intense but informal exchange of views at the frontiers of a subject aims at identifying directions for future action.
Following a transformation of the programme in 2006 the Series has been re-named and re-organised. Recent volumes on topics not related to security, which result from meetings supported under the programme earlier, may be found in the NATO Science Series.
The Series is published by IOS Press, Amsterdam, and Springer Science and Business Media, Dordrecht, in conjunction with the NATO Emerging Security Challenges Division.
Sub-Series
A. Chemistry and Biology Springer Science and Business Media B. Physics and Biophysics Springer Science and Business Media C. Environmental Security Springer Science and Business Media D. Information and Communication Security IOS Press E. Human and Societal Dynamics IOS Press
http://www.nato.int/science http://www.springer.com http://www.iospress.nl
Sub-Series D: Information and Communication Security – Vol. 36 ISSN 1874-6268 (print) ISSN 1879-8292 (online)
17
