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

[Namhyung Kim <namhyung@kernel.org>]

On Tue, May 19, 2026 at 01:13:35AM -0700, Ian Rogers wrote:
> On Mon, May 18, 2026 at 11:43 PM Namhyung Kim <namhyung@kernel.org> 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.

I didn't think it'd add many temporary code especially for group
handling.  But I'm fine with the single patch if breaking it up would
cause a lot of pains to you.

Thanks,
Namhyung