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From: Ian Rogers <irogers@google.com>
Date: Sun, 26 May 2024 08:20:28 -0700
Message-ID: <CAP-5=fX1XwUrnzrxGgQLK2J46jjsCUq8egbV_9p0eNiVD7-EbQ@mail.gmail.com>
Subject: Re: [GIT PULL] perf tools changes for v6.10
To: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>, Leo Yan <leo.yan@linux.dev>, 
	Namhyung Kim <namhyung@kernel.org>, Mark Rutland <mark.rutland@arm.com>, 
	Ingo Molnar <mingo@kernel.org>, Thomas Gleixner <tglx@linutronix.de>, Jiri Olsa <jolsa@kernel.org>, 
	Adrian Hunter <adrian.hunter@intel.com>, Clark Williams <williams@redhat.com>, 
	Kate Carcia <kcarcia@redhat.com>, linux-kernel@vger.kernel.org, 
	linux-perf-users@vger.kernel.org, Anne Macedo <retpolanne@posteo.net>, 
	Bhaskar Chowdhury <unixbhaskar@gmail.com>, Ethan Adams <j.ethan.adams@gmail.com>, 
	James Clark <james.clark@arm.com>, Kan Liang <kan.liang@linux.intel.com>, 
	Thomas Richter <tmricht@linux.ibm.com>, Tycho Andersen <tycho@tycho.pizza>, 
	Yang Jihong <yangjihong@bytedance.com>
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On Sun, May 26, 2024 at 4:10=E2=80=AFAM Arnaldo Carvalho de Melo
<acme@kernel.org> wrote:
> Ian's has been working on this for long time, testing all this takes a
> lot of time and requires access to lots of hardware not easily available
> for all of us, so its bound to break here and there, what we do when
> this happens depends on when the problem is detected, and today Linus is
> expected to close the merge window, so a revert is the technical, if not
> pleasant thing to do now.

Agreed. I think the only other option is:
https://lore.kernel.org/lkml/20240525152927.665498-1-irogers@google.com/
and then when specifying the CPU cycles event on these Ampere systems
you have to do:

$ perf record -e 'armv8_pmuv3_0/cycles/P' ...

but Linus isn't happy with having to specify a PMU like that. As that
is an ARM/Ampere only problem I'm not sure it is so bad.

Thanks,
Ian

> - Arnaldo