Re: [PATCH 1/4] arm_pmu: Add PERF_PMU_CAP_EXTENDED_HW_TYPE capability

From: Will Deacon <will@kernel.org>
To: Ian Rogers <irogers@google.com>
Cc: James Clark <james.clark@arm.com>,
	linux-kernel@vger.kernel.org, Mark Rutland <mark.rutland@arm.com>,
	linux-arm-kernel@lists.infradead.org,
	Anshuman Khandual <anshuman.khandual@arm.com>,
	Peter Zijlstra <peterz@infradead.org>,
	Ingo Molnar <mingo@redhat.com>,
	Alexander Shishkin <alexander.shishkin@linux.intel.com>,
	Jiri Olsa <jolsa@kernel.org>, Namhyung Kim <namhyung@kernel.org>,
	Adrian Hunter <adrian.hunter@intel.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	Borislav Petkov <bp@alien8.de>,
	Dave Hansen <dave.hansen@linux.intel.com>,
	x86@kernel.org, "H. Peter Anvin" <hpa@zytor.com>,
	Kan Liang <kan.liang@linux.intel.com>,
	linux-perf-users@vger.kernel.org,
	Arnaldo Carvalho de Melo <acme@kernel.org>
Subject: Re: [PATCH 1/4] arm_pmu: Add PERF_PMU_CAP_EXTENDED_HW_TYPE capability
Date: Fri, 21 Jul 2023 11:21:31 +0100	[thread overview]
Message-ID: <20230721102131.GA12457@willie-the-truck> (raw)
In-Reply-To: <CAP-5=fVpjJLBNCd4LJ7krX1tpqUT-S_DCRebXR1ioTCGFsF6Pw@mail.gmail.com>

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@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@google.com>
> > >> Signed-off-by: James Clark <james.clark@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

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