[PATCH 0/3] RFC: Platform Support for AMD Zen and AVX2/AVX

[Adhemerval Zanella]

On 16/03/2020 03:44, Prem Mallappa via Libc-help wrote:
> From: Prem Mallappa <Premachandra.Mallappa@amd.com>
> 
> Hello Glibc Community,
> 
> This is in response to
> 
> [1] https://sourceware.org/bugzilla/show_bug.cgi?id=24979
> [2] https://sourceware.org/bugzilla/show_bug.cgi?id=24080
> [3] https://sourceware.org/bugzilla/show_bug.cgi?id=23249
> 
> It is clear that there is no panacea here. However,
> here is an attempt to address them in parts.

Thanks for working on this. I have wrote a open letter after I
read some mishandled criticism that glibc was worsening AMD
performance on purpose [1]. It is good to see some response from
AMD itself.

About the patch, I would ask you to send it to libc-alpha
instead [2], this maillist is usually for glibc questions including 
build problems and library usage. Patches discussions, even
RFC ones, are done on libc-alpha.

Regarding the patch, it looks good in general but I would ask
you to remove the 'Signed-off-by:' (we don't use DCO, but rather
copyright assignments).

[1] https://sourceware.org/pipermail/libc-alpha/2019-September/106474.html
[2] https://sourceware.org/mailman/listinfo/libc-alpha


> 
> From [1], enable customers who already have
> "haswell" libs and has seen perf benifits by loading
> them on AMD Zen.
> (Load libraries by placing them in LD_LIBRARY_PATH/zen
> or by a symbolic link zen->haswell)
> 
> From [2] and [3]
> And, A futuristic generic-avx2/generic-avx libs,
> enables OS vendors to supply an optimized set.
> And haswell/zen are really a superset, hence
> keeping it made sense.
> 
> By this we would like to open it up for discussion
> The haswell/zen can be intel/amd
> (or any other name, and supply ifunc based loading
> internally)
> 
> Prem Mallappa (3):
>   x86: Refactor platform support in cpu_features
>   x86: Add AMD Zen and AVX2/AVX platform support
>   x86: test to load from PLATFORM path
> 
>  sysdeps/x86/cpu-features.c | 113 ++++++++++++++++++++++---------------
>  sysdeps/x86_64/Makefile    |   3 +-
>  2 files changed, 69 insertions(+), 47 deletions(-)
>