linux-kernel - Re: [PATCH 1/2] perf/x86/amd/core: Update stalled-cycles-* events for Zen 2 and later

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Message-ID: <ZgKB5hMlt87E5VhI@gmail.com>
Date: Tue, 26 Mar 2024 09:05:58 +0100
From: Ingo Molnar <mingo@...nel.org>
To: Sandipan Das <sandipan.das@....com>
Cc: Ian Rogers <irogers@...gle.com>, linux-perf-users@...r.kernel.org,
	linux-kernel@...r.kernel.org, x86@...nel.org, peterz@...radead.org,
	acme@...nel.org, namhyung@...nel.org, mark.rutland@....com,
	alexander.shishkin@...ux.intel.com, jolsa@...nel.org,
	adrian.hunter@...el.com, tglx@...utronix.de, bp@...en8.de,
	eranian@...gle.com, ravi.bangoria@....com, ananth.narayan@....com
Subject: Re: [PATCH 1/2] perf/x86/amd/core: Update stalled-cycles-* events
 for Zen 2 and later


* Sandipan Das <sandipan.das@....com> wrote:

> On 3/25/2024 8:04 PM, Ian Rogers wrote:
> > On Mon, Mar 25, 2024 at 12:48 AM Sandipan Das <sandipan.das@....com> wrote:
> >>
> >> AMD processors based on Zen 2 and later microarchitectures do not
> >> support PMCx087 (instruction pipe stalls) which is used as the backing
> >> event for "stalled-cycles-frontend" and "stalled-cycles-backend". Use
> >> PMCx0A9 (cycles where micro-op queue is empty) instead to count frontend
> >> stalls and remove the entry for backend stalls since there is no direct
> >> replacement.
> >>
> >> Signed-off-by: Sandipan Das <sandipan.das@....com>
> > 
> > This looks good to me. Should there be a Fixes tag for the sake of backports?
> > 
> 
> My bad. Yes, there should a fixes tag.
> 
> Fixes: 3fe3331bb285 ("perf/x86/amd: Add event map for AMD Family 17h")
> 
> Ingo, I see that you have already pushed this to the perf/urgent branch.
> Should I send a v2?

That's OK, no need, I've amended the commits in perf/urgent. 2019 is quite 
a way back for a Fixes tag though. :-)

Thanks,

	Ingo