linux-kernel - Re: [PATCH v1] perf arm: Workaround ARM PMUs cpu maps having offline cpus

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Date: Mon, 10 Jun 2024 10:33:18 -0700
From: Ian Rogers <irogers@...gle.com>
To: Leo Yan <leo.yan@....com>
Cc: Suzuki K Poulose <suzuki.poulose@....com>, Mike Leach <mike.leach@...aro.org>, 
	James Clark <james.clark@....com>, John Garry <john.g.garry@...cle.com>, 
	Will Deacon <will@...nel.org>, Leo Yan <leo.yan@...ux.dev>, 
	Peter Zijlstra <peterz@...radead.org>, Ingo Molnar <mingo@...hat.com>, 
	Arnaldo Carvalho de Melo <acme@...nel.org>, Namhyung Kim <namhyung@...nel.org>, 
	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>, 
	coresight@...ts.linaro.org, linux-arm-kernel@...ts.infradead.org, 
	linux-perf-users@...r.kernel.org, linux-kernel@...r.kernel.org, 
	Yicong Yang <yangyicong@...wei.com>
Subject: Re: [PATCH v1] perf arm: Workaround ARM PMUs cpu maps having offline cpus

On Mon, Jun 10, 2024 at 6:30 AM Leo Yan <leo.yan@....com> wrote:
[snip]
> I did a test for this patch, it works well for me.
>
> Tested-by: Leo Yan <leo.yan@....com>
>
> Just a nitpick and I think it is not an issue caused by this patch.
> After hotplug off one CPU and then if specify the CPU with option '-C',
> the 'perf stat' command still continues to run. This is inconsistent
> with the 'perf record' which exits with failures immediately.
>
> Maybe consider to send an extra patch to address this issue?

As you say, this doesn't relate to the problem fixed here. I don't
have a problem with the command line behavior change but I think my
getting shouted at budget is fairly well exhausted. How about we trade
issues, if the following get fixed:

Renaming of the cycles event in arm_dsu_pmu.c - I'd say this is a top
priority issue right now.
Fixing ARM hybrid default perf stat (it is crazy we can accept this
being broken), opening events on both BIG.little PMUs as done here:
https://lore.kernel.org/lkml/20240510053705.2462258-4-irogers@google.com/

I'll address this.

Thanks,
Ian