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From: Stephane Eranian <eranian@google.com>
Date: Wed, 15 Mar 2017 19:27:30 -0700
Message-ID: <CABPqkBR6V80y6Ce0KFBzW=K-QRXMwp3kT+7+QkvijuWnP16WjQ@mail.gmail.com>
Subject: Re: [PATCH] perf/record: make perf_event__synthesize_mmap_events() scale
To: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>,
        LKML <linux-kernel@vger.kernel.org>,
        Peter Zijlstra <peterz@infradead.org>, Ingo Molnar <mingo@kernel.org>,
        Jiri Olsa <jolsa@redhat.com>, namhyung.kim@kernel.org
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Arnaldo,

On Wed, Mar 15, 2017 at 10:44 AM, Arnaldo Carvalho de Melo
<acme@kernel.org> wrote:
>
> Em Wed, Mar 15, 2017 at 10:08:27AM -0700, Stephane Eranian escreveu:
> > On Wed, Mar 15, 2017 at 6:58 AM, Arnaldo Carvalho de Melo
> > <acme@kernel.org> wrote:
> > > Em Wed, Mar 15, 2017 at 10:50:59AM -0300, Arnaldo Carvalho de Melo escreveu:
> > >> So, fixing up the "tasks" -> "tasks" we end up with something safe and
> > >> that avoids this by now
> > >
> > > "tasks" -> "task", grrr
> > >
> > Oops, yeah, sorry about that.
> > Let me submit a V2 with the fix.
>
> Ok, but what about the other observations, what is the kernel you're
> using?
>
Ok, yeah, I was using an older kernel which still had [stack:tid] annotations.
With more recent kernel, it seems this optimization is not needed.
I guess it would only be useful to people running a new perf on a older kernel.

>
> I think this will not make any difference for any kernel >= 4.9, which
> isn't to say the patch shouldn't be applied, I'm just curious.
>
correct, see above.

>
> - Arnaldo