Re: [PATCH v1] drivers/perf: apple_m1: fix affinity table for event 0x96 and 0x9b

From: Yangyu Chen
Date: Tue Jul 02 2024 - 06:22:57 EST


> Yangyu, can you please clarify how you came to the conclusion that
> these events didn't count anywhere other than counter 7?
>

IIRC, I came across some web page that says events 0x96 and 0x9b
can only be installed on counter 7 to count Apple AMX, but I can't
find the page now. Since AMX is not usable in Linux, I don't know
if this will affect some other instructions that are usable in
Linux.

There are some other reasons, but I can't say in public.

Even though I can't find the actual usage, I think using count 7
only for these 2 events is safer. If this reason is insufficient,
we can ignore this patch until we find other evidence that this
affinity affects some instructions usable in Linux.

Thanks,
Yangyu Chen