Re: [PATCH v4 1/2] perf tool_pmu: Make tool PMU events respect enable/disable

[Ian Rogers]

On Mon, May 18, 2026 at 11:43 PM Namhyung Kim <namhyung@xxxxxxxxxx> wrote:
>
> On Mon, May 18, 2026 at 06:41:05PM -0700, Ian Rogers wrote:
> > Tool PMU events (duration_time, user_time, system_time) currently
> > count from when the event is opened to when it is read. This causes
> > issues with features like the delay option (-D) or control fd, where
> > events are opened but should not start counting immediately.
> >
> > Make these events behave more like regular counters by implementing
> > proper enable and disable support. Add accumulated_time to struct
> > evsel to track time while enabled, and implement enable/disable CPU
> > callbacks to start/stop counting.
> >
> > Also generalize userspace PMU mixed group handling. Userspace synthetic
> > PMUs (type > PERF_PMU_TYPE_PE_END) do not have kernel implementations and
> > cannot be grouped in the kernel (opened with group_fd = -1), and are
> > skipped by kernel enable/disable calls. Iterate over group members in
> > userspace and manually enable/disable any members if the leader or the
> > member is a non-perf-event open PMU, and synchronize their disabled flags.
>
> Can we divide the commit into smaller pieces?  I think we can have
>
>  * preparation for accumulated_time
>  * implement enable/disable for tool PMU
>  * wire them to evsel__{enable,disable}[_cpu]
>  * support group members properly
>
> What do you think?

That sounds needlessly painful, involving many irrelevant intermediate
states with dead functions and variables. Most of the patch is
confined to tool_pmu, we could make the evsel patch smaller by
removing comments. The changes in evsel are pretty minimal and the
patch is largely confined to tool_pmu.

Thanks,
Ian

> Thanks,
> Namhyung
>
> >
> > Fixes: b71f46a6a708 ("perf stat: Remove hard coded shadow metrics")
> > Reported-by: Francesco Nigro <nigro.fra@xxxxxxxxx>
> > Closes: https://lore.kernel.org/linux-perf-users/20260517093650.2540920-1-nigro.fra@xxxxxxxxx/
> > Signed-off-by: Ian Rogers <irogers@xxxxxxxxxx>
> > Assisted-by: Antigravity:gemini-3-flash
> > ---
> >  tools/perf/util/evlist.c   |  10 +-
> >  tools/perf/util/evsel.c    | 197 ++++++++++++++++++++++-------
> >  tools/perf/util/evsel.h    |  15 ++-
> >  tools/perf/util/tool_pmu.c | 250 +++++++++++++++++++++++++++++--------
> >  tools/perf/util/tool_pmu.h |   4 +
> >  5 files changed, 377 insertions(+), 99 deletions(-)