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[laughingrice]

I can't seem to find a discussion about local memory bank conflict behavior on AMD.

I saw in the documentation that on the GPU that I'm currently working with there are 32 local memory banks and a wave front size of 64 threads. I'm assuming according to these numbers that half a wavefront schedules access to local memory together and can cause bank conflict if accessing the same bank. Is that correct or is the local memory accessing granularity different?

Thanks

[notzed]

See section 6.2 of the amd app opencl programming guide v2.1a, it has all the details.

Seems to be a granularity of 32 threads by my reading, up to float2 access per thread.

(i'd paste an excerpt but i'm reading it on another machine)

[Wenju]

Hi laughingrice,

Some threads access different address in the same bank at the same time, this will generate bank conflicts. All AMD Evergreen GPUs contain a 32K LDS for each compute uint. On high-end GPUs, the LDS contains 32-banks, each bank is four bytes long, and the bank address is determined by bits 6:2 in the adddress. On lower-end GPUs, the LDS contains 16 banks, each bank is still 4 bytes in size, and the bank used is determined by bits 5:2 in the address.

Thank you.