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

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Message-ID: <8ddd5f97-79a9-4608-8a40-871fb70f2725@linaro.org>
Date: Wed, 8 Oct 2025 12:06:14 +0100
From: James Clark <james.clark@...aro.org>
To: Ian Rogers <irogers@...gle.com>
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 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>