June 24, 2009

Scaling Bandwidth

Article Source Linux Magazine
June 24, 2009, 8:05 am

In my last two columns (Small HPC and HPC Hopscotch) I have been talking about multi-core, memory, and HPC programming. The recent release of the AMD six core Opteron got me thinking about this topic. It will soon be possible to buy a 12 core workstation (or even a 48 core version!) I recall the days when a 32 processor cluster (16 nodes with dual single core processors) was a nice addition to any lab or even computing center.

I also talked about memory locality and how multi-core has introduced a new hierarchy, near, near-by, and non-local memory. In the past an MPI programmer really thought about local memory and non-local (distant) memory on another node. Distant memory was only changed by sending a distant process a message using MPI. Near-by or SMP memory with a bunch of cores attached represents a different (although not all that new) programming paradigm for HPC users. You can still run MPI programs on SMP systems, but a threaded shared memory programming model is also attractive as you don’t need any of that “MPI stuff.” Seems like the cluster may become obsolete for all but those really big jobs...

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