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Explore the changing role of Open Fabrics in HPC, focusing on InfiniBand performance, productivity, and power management. Learn about key advancements and challenges in MPI-based systems.
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MPI and OFADivergent interests? Dan Caldwell, VP WW Channel Sales Scali, Inc
The role of OFA in HPC • The traditional role of Open Fabrics focuses on cables that connect motherboards, switches, and storage in clusters • Growth of processors in HPC expected to be 30% in 2010 (per IDC), and number of cores per processor is 55% (estimate) and increasing • Therefore the bulk of the “HPC Interconnect Fabric” is moving from cables to the server motherboard and the various local buses OFA Presentation
MPI Performance in HPC systems • Scali has always been the performance MPI leader • http://www.supercomputingonline.com/article.php?sid=15357 • However, we suggest that OFA adopt a recommended performance measurement methodology • Productivity, or ‘jobs per day’, on a cluster • How do you know how well OFA is doing? • OFA must examine the performance within a multi-core node • A 16 core “Personal Supercomputer” will still run legacy MPI applications OFA Presentation
Single Node, 8 cores, osu_bw, 8 byte, Intel Xeon 3.00GHz (X5365) OFA Presentation
MPI enables other HPC functionality • Infiniband Trunking • Combining IB channels for greater throughput • Done for Sun / Tsukuba University in Japan • Suspend / Resume and Checkpoint – Restart • Generic functionality - not application specific • Demonstrated job migration with HPC4U in Brussels, February 11, 2008 • And…. MPI based Power Management • Today – AMD / Barcelona only OFA Presentation
”Waiting as fast as it can” (CPU spinning) – examples (AMD Barcelona Quad Core): Power Saving Potential Zone Power Saving Potential Zone Considering 20 microseconds to change power states in an Quad core Opteron, latency above 10 milliseconds in an MPI collectivecan trigger a ”throttle down”. In a call with a 10 millisecondlatency, 20 microseconds to throttle down plus 200 to re-establishfull speed would use only 2.5% of the time of the call. OFA Presentation
Real World Initial Tests - SPEC MPI2007 OFA Presentation
Conclusions • MPI and OFA need to co-exist, but we both need to expand our reach in HPC • Open Fabrics needs to embrace new functionality, performance metrics, and definitions of ‘fabric’ • Power savings, user-model (core affinity policies), best practices in interconnect design, and emphasis on continued performance across the entire HPC system is critical to the relevancy of OFA. OFA Presentation