The Multi-Stream Processor

Multi-streaming works on loops

In simple cases it acts as a pipe/register/cache multiplier

• Can result in super-linear speedups for appropriately sized problems

Loops that don’t vectorize (e.g. outer loops) can be streamed

• Can stream outer loops while vectorizing inner loops

Must eliminate conditions that inhibit streaming

do j=1,1000

a(j)=b(j)*2.71828

end do

SSP0: j=1, 250

SSP1: j=251, 500

SSP2: j=501, 750

SSP3: j=751, 1000

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• In its simplest form, MSP code implements a loop-level parallelism similar to what may be accomplished using OpenMP or auto-tasking.

• For example, when a generic loop is encounted the iterations are partitioned over the individual SSPs that make up the MSP.

• The MSP has certain performance advantages relative to traditional auto-tasking (tighter hdw integration, low ovrhd)