New issue
Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.
By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.
Already on GitHub? Sign in to your account
openblas: re-enable AVX512 support #97306
Conversation
AVX512 support was disabled due to an issue in the AVX512 DGEMM kernel: NixOS#59708 However, this kernel has been replaced upstream a while ago: https://github.com/xianyi/OpenBLAS/releases/tag/v0.3.8 And they have enabled AVX512 kernels since then.
The main reason I disabled it was the negative performance impact. Did you do you a benchmark on a AVX512 enabled CPU? |
For one of my models (a transformer network), enabling AVX512 kernels gives a 22% improvement on a Xeon Gold 6138. |
OK, I see. The Xeon Gold 6138 has FMA/AVX512 units but the a lot of smaller models only have a single unit (which were the ones that had a worse performance than just using only AVX2). AVX512 is really a mixed bag. I'll try to run a test in the next days on a Xeon Silver to see how it behaves there. Is it possible to turn off at run-time? |
I will also try benchmarking my MacBook Air, which only has a single unit.
Seems like not on a per-feature bases, but it can be done on a core type basis with the |
@ofborg eval |
There was a problem hiding this comment.
Choose a reason for hiding this comment
The reason will be displayed to describe this comment to others. Learn more.
I'm happy to keep our configuration as close to upstream as possible.
Motivation for this change
AVX512 support was disabled due to an issue in the AVX512 DGEMM
kernel:
#59708
However, this kernel has been replaced upstream a while ago:
https://github.com/xianyi/OpenBLAS/releases/tag/v0.3.8
And they have enabled AVX512 kernels since then.
cc @markuskowa
Things done
sandbox
innix.conf
on non-NixOS linux)nix-shell -p nixpkgs-review --run "nixpkgs-review wip"
./result/bin/
)nix path-info -S
before and after)