linux-kernel - Re: [PATCH v7 00/27] Legacy hardware/cache events as json

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Message-ID: <CAP-5=fUr7UD1GEU67ZmB9xy6LWbYoeBgBM14_tW-tHhTdGFzDg@mail.gmail.com>
Date: Wed, 8 Oct 2025 07:53:51 -0700
From: Ian Rogers <irogers@...gle.com>
To: James Clark <james.clark@...aro.org>
Cc: Peter Zijlstra <peterz@...radead.org>, Ingo Molnar <mingo@...hat.com>, 
	Arnaldo Carvalho de Melo <acme@...nel.org>, Namhyung Kim <namhyung@...nel.org>, 
	Alexander Shishkin <alexander.shishkin@...ux.intel.com>, Jiri Olsa <jolsa@...nel.org>, 
	Adrian Hunter <adrian.hunter@...el.com>, Xu Yang <xu.yang_2@....com>, 
	Thomas Falcon <thomas.falcon@...el.com>, Andi Kleen <ak@...ux.intel.com>, 
	linux-kernel@...r.kernel.org, linux-perf-users@...r.kernel.org, 
	Atish Patra <atishp@...osinc.com>, Beeman Strong <beeman@...osinc.com>, Leo Yan <leo.yan@....com>, 
	Vince Weaver <vincent.weaver@...ne.edu>
Subject: Re: [PATCH v7 00/27] Legacy hardware/cache events as json

On Wed, Oct 8, 2025 at 4:06 AM James Clark <james.clark@...aro.org> wrote:
> On 05/10/2025 7:24 pm, Ian Rogers wrote:
> > Mirroring similar work for software events in commit 6e9fa4131abb
> > ("perf parse-events: Remove non-json software events"). These changes
> > migrate the legacy hardware and cache events to json.  With no hard
> > coded legacy hardware or cache events the wild card, case
> > insensitivity, etc. is consistent for events. This does, however, mean
> > events like cycles will wild card against all PMUs. A change doing the
> > same was originally posted and merged from:
> > https://lore.kernel.org/r/20240416061533.921723-10-irogers@google.com
> > and reverted by Linus in commit 4f1b067359ac ("Revert "perf
> > parse-events: Prefer sysfs/JSON hardware events over legacy"") due to
> > his dislike for the cycles behavior on ARM with perf record. Earlier
> > patches in this series make perf record event opening failures
> > non-fatal and hide the cycles event's failure to open on ARM in perf
> > record, so it is expected the behavior will now be transparent in perf
> > record on ARM. perf stat with a cycles event will wildcard open the
> > event on all PMUs, however, with default events the cycles event will
> > only be opened on core PMUs.
> >
>
> Hi Ian,
>
> The previous issues seem to be fixed, I don't see any Perf test
> regressions or issues when there is an uncore PMU with a cycles event.
>
> Tested-by: James Clark <james.clark@...aro.org>

Thanks James!

Ian