Stanford Streaming Supercomputer (SSS) Fall Quarter 2002 Wrapup Meeting

1. Stanford Streaming Supercomputer (SSS) Fall Quarter 2002 Wrapup Meeting Bill Dally, Computer Systems LaboratoryStanford University December 10, 2002

2. Overview • Where we are today • First year goal was met: demonstrated feasibility on single node • Feedback from site visit team was very positive • Potential for a big impact on scientific computing • But still much to do! • Key FY03 goals • Get long-term software infrastructure in place • Select approach, implement baseline Brook to SSS compiler • Multi-node versions that scale • Language, compiler, simulator • Tackle hard problems: 3-D, Irregular neighborhoods/sparse matrix solve • Language support, numerics support, evaluate on simulator • Refine architecture • Cluster organization, aspect ratio, register organization, memory organization • Industrial Partner • Start serious discussions, outreach to build support, close partner in 04

3. But first, lets review our overall goal Exploit capabilities of VLSI to realize cost-effective scientific computing.

4. The big picture • VLSI technology enables us to put TeraOPS on a chip • Conventional general-purpose architecture cannot exploit this • The problem is bandwidth • Streams expose locality and concurrency • Perform operations in record (not operation as with vector) order • Enables compiler optimization at a larger scale than scalar processing • A stream architectureachieves high arithmetic intensity • Intensity = arithmetic rate/bandwidth • Bandwidth hierarchy, compound stream operations • A Streaming Supercomputer is feasible • 100GFLOPS (64-b) on a chip, 1TFLOPS single-board computer, PFLOPS systems

5. Review – What is the SSS Project About? • Exploit streams to give 100x improvement in performance/cost for scientific applications vs. ‘cluster’ supercomputers • From 100 GFLOPS PCs to TFLOPS single-board computers to PFLOPS supercomputers • Use layered programming system to simplify development and tuning of applications • Stream languages • Streaming virtual machine • Demonstrated feasibility of streaming scientific computing in year 1 • Refine architecture and programming system in year 2 • Demonstrate realistic applications (3D, irregular) • Build usable compiler • Resolve architecture questions – aspect ratio, conditional execution, sparse clusters, reg organization, memory system, etc… • Build a prototype and demonstrate CITS applications in years 3-6 • With industrial and government partners • Broaden our base of support

6. Software Infrastructure • Compiler • Decide on flow from Brook->SVM->SSS • Select base compiler • ORC, Gnu, SUIF, Tendra, others… • “Spike” a simple program from Brook->SSS • Optimizations • SVM Simulator

7. 3-D Applications • StreamFLO • StreamFEM • StreamMD/Gromacs

8. Irregular Grids • Need an application • Brook support for variable degree • Architecture/run-time support

9. Multi-Node Execution • Brook support • Manual partitioning for first step • Simple application on SVM simulator

10. Industrial Partner • Candidates • Cray, IBM, Sun, HP, SGI, Intel • Initial discussion • Present SSS project and results to date • Discuss collaboration models • Identify next steps

11. Outreach • National Labs • Los Alamos • Livermore • Sandia • Other Government • NASA • DARPA • DoD (Charlie Holland) • AFOSR • User communities

12. Software Fall 02 Goals • Brook • Multi-node issues: • Synchronization primitives • Data Partitioning • Variable length records • SVM • Multi-node simulator • Performance numbers for 3 apps • Compilation • Pick new infrastructure & design compiler (Reservoir) • Generate SVM code from Brook – (StreamC to SVM) • SVM to {SMP, graphics, SSS} (SVM is SMP) • Run-Time (Software services) • Identify issues • Issues • Variable length records? With stencils?

13. Software Win 02 Goals Brook • Define carefully the semantics of the operators • Work on “views of memory” abstraction • Support for partitioning, shared memory, naming, fitting into stream abstraction • Support for irregular neighborhoods • Multithreaded version (Christos) • Concrete Winter goals [Ian/Frank] • Review of the language [Pat] • Partitioning (UPC) • Multi-node/Multi-threaded version • Irregular support – w/ application • PPoPP paper • MD on BRT

14. Software Win 02 Goals SVM • Finish prototype single node implementation [Done] • Compiler issue • Implement multinode version • w/ multi-node app. • Start with one that runs on one processor [Francois] • Multithreaded on SMP – on SGI [+] • Cluster version [++] • SVM to simulator path • Mattan – not an intermediate between Brook and SSS

15. Software Win 02 Goals (3 of 3) • Start regular meetings • Compiler • Decide on flow from Brook->SVM->SSS [Mattan] • Requirements • Select base compiler [Jayanth] • ORC, Gnu, SUIF, Tendra, others… • “Spike” a simple program from Brook->SSS [Mattan/Jayanth ++] • Brook to Nvidia • Optimizations [Spring] • Run time • Write a white paper

16. Application Fall 02 Goals • SteamMD • Migrate to Gromacs • StreamFlo • Complete • 3D • StreamFEM • 3D • Sparse LA • Scalability – multiple nodes • Look at Sierra, purple benchmarks: ppm, sweep3D

17. Application Win 02 Goals • StreamFLO[Fatica] • Partioned version; scalable • Convert to 3D • StreamFEM [Barth] • Partioned version; scalable • Convert to 3D • Sparse LA • StreamMD [Eric/student] • Migrate to GROMACS [Vijay Pande/Michael Levitt groups] • Redo inner (force) and outer (neighbor) loops • Partitioned version; scalable • Finish port to NV30: build cluster and folding@home • Model applications [Ron/Frank] • Model PDES with sparse matrix solves • An irregular application [Ron/Frank] • Look at Sierra, purple benchmarks: ppm, sweep3D [delay]

18. Architecture Fall 02 Goals • Simulator • Multi-node working • Indexable SRF • Scalar processor • Point Studies • Conditionals • Aspect ratio • Indexable SRF • Add & Store (remote ops in general) • Iterative operations & extended precision • Network • Spec • Flesh out I/O • App studies

19. Architecture Win 02 Goals • Single-Node Simulator [Jung-Ho, Knight] • 64-bit support, MULADD, Scalar Processor • Multi-Node Simulator [Jung-Ho, Abhishek] • Network model • Multi-node mechanisms • Point Studies • Aspect ratio • SSE vs VLIW • Conditional execution [Mattan/Ujval] • Sparse clusters • SRF organization [Nuwan] • Cache alternatives [Jung Ho] • Add and store study [Jung Ho] • I/O • Iterative operations [Francois]

20. Special Win 02 Goals • Fix website [Pat] • Public and private websites • Name that computer • Mississippi • Axios • Submit names to Mattan • Bill, Pat, Bill to choose • Project Party

21. Winter Quarter Meeting Schedule • 1/7 Ron Anything • 1/14 Francois/Mattan What is SVM • 1/21 Fatica 3D Flo • 1/28 Pat RTSL partitioning • 2/4 Bill Carlson [Pat] UPC • 2/11 Francois/Ian Discussion of targets SSS/CG/MPI • 2/18 Tim B. Irregular grid • 2/25 Mattan Compilation Infrastructure • 3/4 Jung Ho Add & Store • 3/11 Bill Wrapup

22. Papers • Arch • Indexable SRFs (Nuwan) • Streaming Supercomputer Overview (Tim K.) • Streaming on conventional CPUs (Mattan) • Conditionals (Ujval) • Remote Ops (Jung Ho) • Aspect Ratio (?) • Data parallel (SSE) vs. ILP (VLIW) • Software • Design of Brook (Ian) • Data parallel programming on graphics HW (Pat) • Brook to CG • Compiler • Apps • Gromacs • StreamFEM (Tim2) • Overview (Bill and Pat)