erman_amd

counting number of work groups and work group distribution

Discussion created by erman_amd on Jun 29, 2011
Latest reply on Jul 9, 2011 by Jawed

Hi,

When collect trace from my application, the AMD APP Profiler reports:

GlobalWorkSize: 327680

Wavefronts: 5120

I leave the local work size to NULL and execute the kernel in 1D NDRange.

On 5870 GPU, the MAX_WORK_GROUP_SIZE is 256, so one work-group has maximum 256 work-items or 4 wavefronts.

Questions: 

1. Since it has 5120 wavefronts, does it mean, it has  5120/4 = 1280 Work-group?

2. AFAIK, work-groups are distributed (equally??) to SIMD engine. 5870 has 20 SIMD engines, so each SIMD engine get 1280/20 = 64 work-groups (= 64 x 4 wavefronts = 256 wavefronts = 16384 work-items). Is it correct?

Thank you.

 

 

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