The HeartBeat modelA platform abstraction enabling fast prototyping
of real-time applications on NoC-based MPSoC on FPGA
Francesco Robino, Johnny Oberg
KTH Royal Institute of Technology
ReCoSoC 2013
F. Robino (KTH) The HeartBeat model 11-07-2013 1 / 16
Overview of the talk
Motivation
What is the problem?Benefits solving the problem
Our solution
Modeling techniquesOur ideaFrom idea to implementationExperimental evidences and examples
Conclusion
F. Robino (KTH) The HeartBeat model 11-07-2013 2 / 16
Motivation: Embedded systems modeling
Embedded systems are getting very complex
We want to abstract, reduce details in the system model
We want System Design Automation to automatically add details
it implements the embedded application on multi-processor platformsthe automated synthesis of the whole system must be fast!
F. Robino (KTH) The HeartBeat model 11-07-2013 3 / 16
Motivation: Embedded system architecture
Embedded architectures are getting verycomplex
details are increasing!
sea-of-cores /processors
NoC-based MPSoC
Pe0 Pe2
Pe3
Pe6
Pe5
Pe8
Pe9 Pe11
Pe1
Pe4
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F. Robino (KTH) The HeartBeat model 11-07-2013 4 / 16
The problem
Pe Pe
PePe
Pe
Pe
Huge abstraction gap
Huge design space
Platform allocationProcesses bindingProcesses schedule
Platform:
complex to programcomplex to generate
Filling the gap through design automation: benefits
Reduces time to market, reduces errors, reduces complexity...
F. Robino (KTH) The HeartBeat model 11-07-2013 5 / 16
Modeling techniques
The theory of models of computation (MoCs)
A MoC defines communication and execution rules between nodesexecuting the operations.
The MoC rules can be described through formal notation (math)
Embedded application modeled as a set of communicating processes
F. Robino (KTH) The HeartBeat model 11-07-2013 6 / 16
The synchronous MoC
We use the synchronous MoC
Used in synchronous languages (i.e. Lustre) to guarantee real-time
Combinatorial application in the synchronous MoC:
+1p
TagEventValue
0 1 2 3
4 7 6 9
0 1 2 3
3 6 5 8
Application with memory in the synchronous MoC:
+1p dly
0 1 2 3
0 4 7 6
Tag 0 1 2 3
3 6 5 8
F. Robino (KTH) The HeartBeat model 11-07-2013 7 / 16
From synchronous MoC to NoC-based MPSoC
+1p dly
0 1 2 3
0 4 7 6
Tag 0 1 2 3
3 6 5 8
Pe0 Pe1
+1p dly +1
p dlyTime 0 1 2 3 ms
3 6 5 8
0 1 2 3 ms
0 4 7 6
F. Robino (KTH) The HeartBeat model 11-07-2013 8 / 16
From synchronous MoC to NoC-based MPSoC
We define an intermediate layer, the HeartBeat model:fills the abstraction gap adding details about timing and architectureenables the MPSoC to expose the same semantics of the MoCcritical path (RTL, sea of gates) HB period (MoC, sea of cores)
+1p dly
Pe0
0 1 2 3 ms
3 6 5 8
+1p
NoC
0 4 7 9
0 1 2 3 ms
εc
Pe1HB period
HB ticks
...
The HeartBeat model (for this simple example)
tHB ≥M
maxm=0
(tεi + tci )
F. Robino (KTH) The HeartBeat model 11-07-2013 9 / 16
A HW/SW co-design flow based on the HeartBeat model
Process(es) functionalityC file(s)
XML platform configurationand process(es) mapping
NoC system Generator
Target FPGA
Back
-end
flow
Fron
t-en
d flo
w
Graphical User InterfaceApplication view Platform view
Allocation
Binding
Scheduling
Software synthesis of C wrappers for MoC support
F. Robino (KTH) The HeartBeat model 11-07-2013 10 / 16
SW synthesis technique
Application view:synthesis of software to access NoC API and synchronize on HB tick
Initialize processes
Execute PE processes
HB tickreceived?
Begin
Y
N
p0_mainp1_main...pn_main
Begin
Messagereceived?
Execute user specified functionality
Previous process communication
concluded?
Send result to next process
End
Y
N
Y
N
Pe0
F. Robino (KTH) The HeartBeat model 11-07-2013 11 / 16
HW synthesis technique
Platform view:synthesis of NoC-based MPSoC with HeartBeat support
A HW timer generates HB ticksThe HB period (timer period) can be defined by the user, following theHeartbeat model
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F. Robino (KTH) The HeartBeat model 11-07-2013 12 / 16
Case study
A neural network, 4 layers, each layer 100 neurons
Each layer on a separate PE (4 layers, 4 PEs, 2× 2 NoC)
Generation of files for prototype synthesis on FPGA < 1 second
n0
n1
n99
w0
w1
P0 P1
f
sum
P2 P3
Pe0
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F. Robino (KTH) The HeartBeat model 11-07-2013 13 / 16
Case study
Optimize the application: find the minimal HB period of the system
The HeartBeat model (for this simple example)
tHB ≥M
maxm=0
(tεi + tci )
tεi has been found through extensive emulations. Its value is 5,97 ms
tci can be found following models proposed in referenced papers
The HeartBeat period is totally dominated by tεi , it is an order ofmagnitude larger than tciConcluding the maximal HB frequency of the system is 1
5,97 ' 150 Hz
F. Robino (KTH) The HeartBeat model 11-07-2013 14 / 16
Results and related work
Design flow MAMPS Our workTarget platform 2 processors 4 processorsPlatform interconnection 2 × 1 NoC 2 × 2 NoCCreating system model manual(SDF) manual(SY)Creating application model manual semiautomaticGenerating architecture model 1 second ∼100 millisecMapping the design 1 minute manualGenerate Xilinx/Altera project 16 seconds ∼500 millisec
Table: SDA flows steps rapidity
COMPSOC Open-Scale MAMPS Our workMoC entry HSDF KPN SDF SyncNoC arch. Mesh Mesh Mesh MeshNoC dim. 2D 2D 2D 2D,3DAPI generation Y N N YPrototype Y Y Y YOS avail. Y Y N N
Table: SDA flows properties comparison
F. Robino (KTH) The HeartBeat model 11-07-2013 15 / 16
Conclusion
The HeartBeat model is an intermediate platform model bridging theabstraction gap between the synchronous MoC and a NoC-basedMPSoC platform
The HeartBeat model enables a SDA flow to synthesize an embeddedapplication onto a NoC-based MPSoC on FPGA, provided that thetiming constraints of the HeartBeat model are met
The design flow reduces the complexity of designing embeddedsystems for NoC-based MPSoCs through a GUI
The automated flow speeds up the design process of embeddedsystems.
More info and tutorials
https://forsyde.ict.kth.se/noc generator/
F. Robino (KTH) The HeartBeat model 11-07-2013 16 / 16
