Raistmer

workitems distribution between SIMDs

Discussion created by Raistmer on May 1, 2010
Latest reply on May 3, 2010 by Raistmer
how wavefronts will be formed?

Kernel executed on 32x10 execution domain (for example)
And GPU has 10 SIMDs (HD4870).
How threads (workitems) will be distributed between them?
Possible variants:
1) will be formed 10 wavefronts with 32 threads each, each SIMD will execute single wavefront, all SIMDs are busy.
2) 5 wavefronts with 64 threads in each will be formed, 5 SIMDs will be loaded with these wavefronts, another 5 SIMDs stay idle.

What variant (maybe some third?) will be realized?

And what if I set workgroup size to 32 as kernel call parameter, will it define variant 1?

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