linux-kernel - Re: [PATCH v1] perf evlist: Force adding default events only to core PMUs

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Message-ID: <CAM9d7chV8YOCj8=SGs0f60UGtf+N2+X=U+Brg246bFoPXBXS+g@mail.gmail.com>
Date: Wed, 29 May 2024 22:35:12 -0700
From: Namhyung Kim <namhyung@...nel.org>
To: Ian Rogers <irogers@...gle.com>
Cc: Arnaldo Carvalho de Melo <acme@...nel.org>, James Clark <james.clark@....com>, Leo Yan <leo.yan@...ux.dev>, 
	Linus Torvalds <torvalds@...ux-foundation.org>, Peter Zijlstra <peterz@...radead.org>, 
	Ingo Molnar <mingo@...hat.com>, Mark Rutland <mark.rutland@....com>, 
	Alexander Shishkin <alexander.shishkin@...ux.intel.com>, Jiri Olsa <jolsa@...nel.org>, 
	Adrian Hunter <adrian.hunter@...el.com>, Kan Liang <kan.liang@...ux.intel.com>, 
	Dominique Martinet <asmadeus@...ewreck.org>, linux-perf-users@...r.kernel.org, 
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v1] perf evlist: Force adding default events only to core PMUs

On Wed, May 29, 2024 at 12:25 PM Ian Rogers <irogers@...gle.com> wrote:
> We can fix the arm_dsu bug by renaming cycles there. If that's too
> hard to land, clearing up ambiguity by adding a PMU name has always
> been the way to do this. My preference for v6.10 is revert the revert,
> then add either a rename of the arm_dsu event and/or the change here.
>
> We can make perf record tolerant and ignore opening events on PMUs
> that don't support sampling, but I think it is too big a thing to do
> for v6.10.

How about adding a flag to parse_event_option_args so that we
can check if it's for sampling events.  And then we might skip
uncore PMUs easily (assuming arm_dsu PMU is uncore).

It might not be a perfect solution but it could be a simple one.
Ideally I think it'd be nice if the kernel exports more information
about the PMUs like sampling and exclude capabilities.

Thanks,
Namhyung