VLVNT Amsterdam 2003 – J. Panman 1
DAQ: comparison with an LHC experimentDAQ: comparison with an LHC experiment
J. Panman
CERN
VLVNT workshop 7 Oct 2003
Use as example CMS (slides taken from Cittolin's talk at LHCC)Take numbers floating around this week as typical performance needs
SUPERFI CI AL!
VLVNT Amsterdam 2003 – J. Panman 1
Data to shore:links per tower/string 1data rate/link 1.6 Gbits/stotal data rate 640 Gbits/s
Comparison of design parametersComparison of design parameters
Take numbers floating around this week as typical performance needsFor simplicity: use a “digitized scenario” (waveforms transmitted)
Data source:sampling frequency 200-400 Mhzsampling precision 8 bitssample length 50-100 nsNo. OMs 10000No. towers/strings 400Background rate 50-200 kHz/OM
Event organization:“Event” window length 10 mssize of data/event 800 Mb
VLVNT Amsterdam 2003 – J. Panman 1
Data to shore:links per tower/string 1data rate/link 1.6 Gbits/stotal data rate 640 Gbits/s
Comparison of design parametersComparison of design parameters
Take numbers floating around this week as typical performance needsFor simplicity: use a “digitized scenario” (waveforms transmitted)
Data source:sampling frequency 200-400 Mhzsampling precision 8 bitssample length 50-100 nsNo. OMs 10000No. towers/strings 400Background rate 50-200 kHz/OM
Event organization:“Event” window length 10 mssize of data/event 800 Mb
Data to surface:Average event size 1 MbyteNo. FED S-link64 ports 700DAQ links (2.5 Gb/s) 512+512Event fragment size 2 kBFED builders (8x8 dual) 64Technology(2004) Myrinet
Total data rate:total data rate 800 Gbits/s
CMS
VLVNT Amsterdam 2003 – J. Panman 1
CreditsCredits
slides taken from Cittolin's talk at LHCC
VLVNT Amsterdam 2003 – J. Panman 1
Front endFront end
Desktop/Servercurrent architecturePeripheral IO bus PCI:33/66 MHz x 32/64 bit100/200/400 MB/sPxx
MEM
Pxx
Pxx
Pxx
264 MB/s
GByte memoryMultiProcessor
PCI
PCI
264 MB/s
Dual PCI
1990' PCI
Pxx
Pxx
Pxx
Pxx
SIO
MEM
200X: PCI-X …
FE digitizerData from a string
DSP-like operation:filter produces time&charge from waveform assume 8 bytes to encode(reduction x3)
Data from a string Readout network
VLVNT Amsterdam 2003 – J. Panman 1
Network configurationsNetwork configurations
EVB staging by switch expansion:EVB staging by switch expansion:
FED -> FE digitizer
VLVNT Amsterdam 2003 – J. Panman 1
CMS – 2 stages: Data to surface & Readout CMS – 2 stages: Data to surface & Readout BuilderBuilder
Readout Builder (up to 8)64x64 x 2.5 Gb/s switchEvent rate 12.5 kHz
2 kByte
16 kByte
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FED Builder (64 units)8x8 x 5 Gb/s switchEvent fragments merger
VLVNT Amsterdam 2003 – J. Panman 1
CMS – DAQ staging : 2 RBs = 25 kHzCMS – DAQ staging : 2 RBs = 25 kHz
FED BuildersProgrammed to send events to two output (odd and even EvNo.)
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VLVNT Amsterdam 2003 – J. Panman 1
CMS – DAQ staging : 8 RBs = 100 kHzCMS – DAQ staging : 8 RBs = 100 kHzD
ata
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Rea
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VLVNT Amsterdam 2003 – J. Panman 1
CMS – 3-D DAQ implementations and CMS – 3-D DAQ implementations and scalingscaling
Readout Builders (x8):Lv-1 max. trigger rate 12.5 kHzRU Builder (64x64) .125 Tbit/sEvent fragment size 16 kBRU/BU systems 64Event filter power 105 SI95EVB technology (2006) Open
Data to surface:Average event size 1 MbyteNo. FED S-link64 ports 700DAQ links (2.5 Gb/s) 512+512Event fragment size 2 kBFED builders (8x8 dual) 64Technology(2004) Myrinet
VLVNT Amsterdam 2003 – J. Panman 1
Comparison of numbersComparison of numbers
Total data rate of km3 detector similar to an LHC detector after the L1 triggerNumber of data sources similar to number of FE Digitizers
Waveform filtering (if possible) reduces the data volume by factor 3Moore's law will help by factor 4-8 compared to LHC
Output rate of HLT farm in km3 (presumably) much lower than 100 Hzx1MbProbably data storage problem much smaller than LHC
HLT processing time/byte looks to be smaller than at LHC (LHC has to reject real physics events)
VLVNT Amsterdam 2003 – J. Panman 1
SummarySummary
DAQ architecture of LHC experiments can be a useful starting point for a design
Similar techniques, but probably smaller requirements
A couple of years later:profit from experienceprofit from performance/price ratio trend
At a first glance the DAQ does look feasable