COSSIM An Integrated Solution to Address the Simulator Gap for Parallel Heterogeneous Systems

Transcription

1 COSSIM An Integrated Solution to Address the Simulator Gap for Parallel Heterogeneous Systems Andreas Brokalakis Synelixis Solutions Ltd, Greee Nikolaos Tampouratzis Teleommuniation Systems Institute, Greee gem5 Workshop ARM Researh Summit 2017 September 11, 2017 COSSIM Consortium Proprietary

2 Motivation Miroproessor and Systems designers annot ignore network interations when designing new system arhitetures, sine networks are an integral part of all parallel systems Too many interations, too ompliated Major optimization opportunities Majority of the existing simulation tools an handle effiiently only parts of a system either only the proessing part or the network Existing simulators are typially single-threaded A parallel approah is required for networked systems simulation if realisti simulation times have to expeted COSSIM Consortium Proprietary 2

3 What is COSSIM? COSSIM is an open-soure framework that an simulate Highly Parallel Systems or more generally Systems of Systems Networking and the proessing simulators are integrated into a single framework Single notion of time, aurate proessing and network interations Easy simulation set-up, exeution and visualization of results through a Graphial User Interfae (Elipse-based) IP-based so that simulation an be distributed Power estimation tools are also integrated in order to aount for the real proessing - network interations Fully funtional version open & free, ommerial support and support for add-on pakages by providing proper extensions COSSIM Consortium Proprietary 3

4 COSSIM Framework Key onept : use well-established proessing and network simulators Retain ompatibility to be able to readily take advantage of all related researh and development work COSSIM is built on top of GEM5, to simulate the omponents of eah proessing node in the simulated system OMNET++, to simulate the real networking infrastruture MPAT / OMNET++ addons to provide energy and power onsumption estimations CERTI (IEEE1516 HLA) to integrate all simulator pakages together COSSIM Consortium Proprietary 4

5 Network Support on gem5 GEM5 - System 0 Ethernet Pakets CPU NIC PCI Etherlink Virtual Link GEM5 - System 1 CPU PCI NIC Master Port Slave Port Current network model of gem5 is restritive: Only two nodes Simple wire (no swith / router) Idential CPU systems Single-thread / simplisti synhronization COSSIM Consortium Proprietary 5

6 Extending gem5 for COSSIM (1) GEM5 - Node 0 CPU GEM5 - Node 1 CPU Master Port Slave Port NIC NIC Etherlink. Etherlink. COSSIMlib COSSIMlib librti librti CERTI HLA (RTIG) COSSIMlib librti Node0 Node1 In the modified version of gem5 (GEM5): Ethernet pakets are aptured and through a ustom library are sent to an HLA server The pakets are sent to a representation of the nodes in the network simulator implementing the ommuniation topology OMNET++ COSSIM Consortium Proprietary 6

7 Extending gem5 for COSSIM (2) GEM5 - Node 0 GEM5 - Node 1 CPU CPU NIC NIC Etherlink. Etherlink. COSSIMlib COSSIMlib librti librti CERTI HLA (RTIG) COSSIMlib librti Node0 Node1 OMNET++ Master Port Slave Port By this proess: An arbitrary number of nodes an be onneted Sophistiated network topologies an be implemented Eah node is independent and therefore heterogeneous systems an be omposed IP-based (HLA) interonnetion allows for parallel / distributed exeution of eah GEM5 instane Additionally: FS simulation only (NIC + OS drivers rq.) X86 + ARM fully supported New and most urrent linux kernel versions running COSSIM Consortium Proprietary 7

8 The Network Simulator Sub System We employ OMNeT++ network simulator Eah GEM5 system is refleted in an OMNET++ HLA-enabled node Challenge: Inompatible network staks between OMNeT++ and GEM5 Developed: ustom-fit funtionality developed at user spae No modifiation to the OMNeT++ -INET ode Fully ompatible with the OMNeT++ legay Preserving OMNET++ funtionality, any supported network topology an be used, inluding network devies and ustom nodes (in the OMNET++ spae not simulated through GEM5) COSSIM Consortium Proprietary 8

9 The Elephant in the Room Integration and Synhronization (1) Synhronization issues arise differenes between gem5 and OMNET++ (event-based) ommuniation between different gem5 systems running independently requirement of a ommon notion of time throughout the whole simulated system Two-stage solution through CERTI HLA Synhronization per node (eah GEM5 node needs to synhronize with its ounterpart network node) Global Synhronization (syn all nodes simultaneously periodially as different types of CPUs with different lok yles Different simulation time) COSSIM Consortium Proprietary 9

10 The Elephant in the Room Integration and Synhronization (2) Mahine 1 GEM5 Simulator NODE 0 Synhronization per node Exhange Data Pakets Mahine 2 NODE 0 NODE 1 GEM5 Simulator NODE 1 OMNET++ Real Network Simulator SynhNode NODE 2 HLA GEM5 Simulator NODE 2 Federation 3 COSSIM Consortium Proprietary 10

11 The Elephant in the Room Integration and Synhronization (2) Mahine 1 GEM5 Simulator NODE 0 Mahine 2 Synhronization per node Exhange Data Pakets Global Synhronization All GEM5 nodes OMNET++ SynhNode NODE 0 NODE 1 GEM5 Simulator NODE 1 OMNET++ Real Network Simulator NODE 2 HLA GEM5 Simulator NODE 2 SynhNode Global Federation COSSIM Consortium Proprietary 11

12 Simulation Time (in seonds) Performane ARM ARM X86 X86 ARM / x86 systems while booting Linux OS One GEM5 instane per physial ore Mahine 1 (Quad-ore) Mahine 2 (12-ore onneted to Mahine 1 through LAN) # of Nodes COSSIM Consortium Proprietary 12

13 Simulation Time (in Seonds) Performane vs Auray Global Synhronization Interval introdues a potential performane bottlenek Restrits how long a GEM5 instane an run freely before pausing for synhronization Affets auray of results (appliation dependent user settable) Example: 4-node ARM systems while booting Linux OS ms 10ms 100ms 1000ms 10000ms COSSIM Consortium Proprietary 13 Global Synhronization Interval (in mse)

14 Thank you! COSSIM Consortium Proprietary 14