From: Jiri Olsa <jolsa@redhat.com>
To: Rob Herring <robh@kernel.org>
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: Tue, 11 Aug 2020 12:50:27 +0200 [thread overview]
Message-ID: <20200811105027.GD699846@krava> (raw)
In-Reply-To: <CAL_Jsq+gfqyqCx3Yuc6TsbXjYSLfJQhhPUnwRVjpJgwL24v1Qg@mail.gmail.com>
On Mon, Aug 10, 2020 at 12:11:23PM -0600, Rob Herring wrote:
> 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
if it works for all events, which I'm not sure of
> which is associated with a evlist rather than a evsel?
not sure what you mean, you can mmap evsel, not evlist
jirka
next prev parent reply other threads:[~2020-08-11 10:50 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
2020-08-11 10:50 ` Jiri Olsa [this message]
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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