linux-kernel - Re: [PATCH v4 0/5] A mechanism for efficient support for per-function metrics

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Message-ID: <CAP-5=fUukVQMRHUQ9Mpx38H-7VNLt4mDj-jaYgn8Tf4zjecD-A@mail.gmail.com>
Date: Fri, 11 Apr 2025 10:34:56 -0700
From: Ian Rogers <irogers@...gle.com>
To: Mark Barnett <mark.barnett@....com>
Cc: Ingo Molnar <mingo@...nel.org>, peterz@...radead.org, mingo@...hat.com, 
	acme@...nel.org, namhyung@...nel.org, ben.gainey@....com, 
	deepak.surti@....com, ak@...ux.intel.com, will@...nel.org, 
	james.clark@....com, mark.rutland@....com, alexander.shishkin@...ux.intel.com, 
	jolsa@...nel.org, adrian.hunter@...el.com, linux-perf-users@...r.kernel.org, 
	linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH v4 0/5] A mechanism for efficient support for per-function metrics

On Fri, Apr 11, 2025 at 4:08 AM Mark Barnett <mark.barnett@....com> wrote:
> Tool Integration
> ==================
>
> We've been using a python script to process the data into a report. We
> can look at implementing this directly in perf report, if that is
> required. However, I'm nervous about making the new feature the default
> behaviour for the tool.
>
> This feature has been integrated into our tools [1] for the last 12
> months, and has received a lot of testing on Arm Neoverse hardware.
> Other platforms have received less rigorous testing. In my opinion, more
> work would be needed to validate the PMU hardware & software
> characteristics of other architectures before this can be made the default.

Hi Mark,

Wrt testing, in v6.14 we've fixed up the python scripting with perf a
bit more and there is an example that parses an event and then dumps
samples here:
https://web.git.kernel.org/pub/scm/linux/kernel/git/perf/perf-tools-next.git/tree/tools/perf/python/tracepoint.py?h=perf-tools-next
There is also the perf script integration for things like flame graphs:
https://web.git.kernel.org/pub/scm/linux/kernel/git/perf/perf-tools-next.git/tree/tools/perf/scripts/python/flamegraph.py?h=perf-tools-next#n96

I don't think work should be gated on cleaning up perf report, top,
etc. which still needs clean up for things like hybrid events. As the
histograms should use the sample's period then I believe things should
just work in much the same way as leader sampling can work. It'd be
worth checking.

Thanks,
Ian