[PATCH 1/4] arm_pmu: Add PERF_PMU_CAP_EXTENDED_HW_TYPE capability

[Will Deacon]

On Thu, Jul 20, 2023 at 10:12:21AM -0700, Ian Rogers wrote:
> On Tue, Jul 11, 2023 at 7:12 AM James Clark <james.clark at arm.com> wrote:
> >
> >
> >
> > On 11/07/2023 13:01, Anshuman Khandual wrote:
> > >
> > >
> > > On 7/10/23 17:51, James Clark wrote:
> > >> This capability gives us the ability to open PERF_TYPE_HARDWARE and
> > >> PERF_TYPE_HW_CACHE events on a specific PMU for free. All the
> > >> implementation is contained in the Perf core and tool code so no change
> > >> to the Arm PMU driver is needed.
> > >>
> > >> The following basic use case now results in Perf opening the event on
> > >> all PMUs rather than picking only one in an unpredictable way:
> > >>
> > >>   $ perf stat -e cycles -- taskset --cpu-list 0,1 stress -c 2
> > >>
> > >>    Performance counter stats for 'taskset --cpu-list 0,1 stress -c 2':
> > >>
> > >>          963279620      armv8_cortex_a57/cycles/                (99.19%)
> > >>          752745657      armv8_cortex_a53/cycles/                (94.80%)
> > >>
> > >> Fixes: 55bcf6ef314a ("perf: Extend PERF_TYPE_HARDWARE and PERF_TYPE_HW_CACHE")
> > >> Suggested-by: Ian Rogers <irogers at google.com>
> > >> Signed-off-by: James Clark <james.clark at arm.com>
> 
> Hi ARM Linux and ARM Linux PMU people,
> 
> Could this patch be picked up for Linux 6.5? I don't see it in the
> tree and it seems a shame to have to wait for it. The other patches do
> cleanup and so waiting for 6.6 seems okay.

I'm only taking fixes for 6.5 and I don't think this qualifies.

If it was an oversight introduced during the recent merge window, then
I'd be happier fixing it up, but 55bcf6ef314a was merged ages ago (v5.12?),
so I think we can wait.

I'll be queuing perf changes for 6.6 next week, so I'll look at this
then.

Cheers,

Will