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From: Rob Herring <robh@kernel.org>
To: Jiri Olsa <jolsa@redhat.com>
Cc: "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	Peter Zijlstra <peterz@infradead.org>,
	Ingo Molnar <mingo@redhat.com>,
	Arnaldo Carvalho de Melo <acme@kernel.org>,
	Mark Rutland <mark.rutland@arm.com>,
	Alexander Shishkin <alexander.shishkin@linux.intel.com>,
	Namhyung Kim <namhyung@kernel.org>
Subject: Re: [RFC] libperf: Add support for user space counter access
Date: Mon, 10 Aug 2020 12:11:23 -0600	[thread overview]
Message-ID: <CAL_Jsq+gfqyqCx3Yuc6TsbXjYSLfJQhhPUnwRVjpJgwL24v1Qg@mail.gmail.com> (raw)
In-Reply-To: <20200808102208.GA619980@krava>

On Sat, Aug 8, 2020 at 4:22 AM Jiri Olsa <jolsa@redhat.com> wrote:
>
> On Fri, Aug 07, 2020 at 05:05:17PM -0600, Rob Herring wrote:
> > x86 and arm64 can both support direct access of event counters in
> > userspace. The access sequence is less than trivial and currently exists
> > in perf test code (tools/perf/arch/x86/tests/rdpmc.c) with copies in
> > projects such as PAPI and libpfm4.
> >
> > Patches to add arm64 userspace support are pending[1].
> >
> > For this RFC, looking for a yes, seems like a good idea, or no, go away we
> > don't want this in libperf.
>
> hi,
> looks great!
>
> I wanted to add this for very long time.. so yes, we want this ;-)

Thanks for the quick feedback. Would this be better implemented as a
fast path for perf_evsel__read()? If so, how to get the mmap data
which is associated with a evlist rather than a evsel?

Rob

  reply	other threads:[~2020-08-10 18:11 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-08-07 23:05 [RFC] libperf: Add support for user space counter access Rob Herring
2020-08-08 10:22 ` Jiri Olsa
2020-08-10 18:11   ` Rob Herring [this message]
2020-08-11 10:50     ` Jiri Olsa
2020-08-11 11:02       ` peterz
2020-08-11 16:49       ` Rob Herring
2020-08-12 13:05         ` Jiri Olsa
2020-08-10 20:24 ` Peter Zijlstra

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