From: Arnaldo Carvalho de Melo <acme@kernel.org>
To: Brendan Gregg <brendan.d.gregg@gmail.com>
Cc: Arnaldo Carvalho de Melo <arnaldo.melo@gmail.com>,
Alexei Starovoitov <alexei.starovoitov@gmail.com>,
David Ahern <dsahern@gmail.com>,
Peter Zijlstra <peterz@infradead.org>,
Frederic Weisbecker <fweisbec@gmail.com>,
Ingo Molnar <mingo@kernel.org>,
Adrian Hunter <adrian.hunter@intel.com>,
Alexander Shishkin <alexander.shishkin@linux.intel.com>,
Alexei Starovoitov <ast@kernel.org>,
He Kuang <hekuang@huawei.com>, Jiri Olsa <jolsa@redhat.com>,
Masami Hiramatsu <mhiramat@kernel.org>,
Milian Wolff <milian.wolff@kdab.com>,
Namhyung Kim <namhyung@kernel.org>,
Stephane Eranian <eranian@google.com>,
Thomas Gleixner <tglx@linutronix.de>,
Vince Weaver <vincent.weaver@maine.edu>,
Wang Nan <wangnan0@huawei.com>, Zefan Li <lizefan@huawei.com>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH/RFC v3] perf core: Allow setting up max frame stack depth via sysctl
Date: Wed, 27 Apr 2016 09:56:02 -0300 [thread overview]
Message-ID: <20160427125602.GN11033@kernel.org> (raw)
In-Reply-To: <CAE40pdcd+mXur=bkHjN8Fb7SgVYNjDbR30rRS=LrqCknAJa9ig@mail.gmail.com>
Em Tue, Apr 26, 2016 at 02:58:41PM -0700, Brendan Gregg escreveu:
> On Tue, Apr 26, 2016 at 2:05 PM, Arnaldo Carvalho de Melo
> <arnaldo.melo@gmail.com> wrote:
> > Em Tue, Apr 26, 2016 at 01:02:34PM -0700, Brendan Gregg escreveu:
> >> On Mon, Apr 25, 2016 at 5:49 PM, Brendan Gregg <brendan.d.gregg@gmail.com> wrote:
> >> > On Mon, Apr 25, 2016 at 5:47 PM, Arnaldo Carvalho de Melo <arnaldo.melo@gmail.com> wrote:
> >> >> Em Mon, Apr 25, 2016 at 05:44:00PM -0700, Alexei Starovoitov escreveu:
> >> >>> yep :)
> >> >>> hopefully Brendan can give it another spin.
> >> >>
> >> >> Agreed, and I'm calling it a day anyway, Brendan, please consider
> >> >> retesting, thanks,
> >> >
> >> > Will do, thanks!
> >>
> >> Looks good.
> >>
> >> I started with max depth = 512, and even that was still truncated, and
> >> had to profile again at 1024 to capture the full stacks. Seems to
> >> generally match the flame graph I generated with V1, which made me
> >> want to check that I'm running the new patch, and am:
> >>
> >> # grep six_hundred_forty_kb /proc/kallsyms
> >> ffffffff81c431e0 d six_hundred_forty_kb
> >>
> >> I was mucking around and was able to get "corrupted callchain.
> >> skipping..." errors, but these look to be expected -- that was
> >
> > Yeah, thanks for testing!
> >
> > And since you talked about userspace without frame pointers, have you
> > played with '--call-graph lbr'?
>
> Not really. Isn't it only 16 levels deep max?
Yeah, stoopid me :-\
> Most of our Linux is Xen guests (EC2), and I'd have to check if the
> MSRs are available for LBR (perf record --call-graph lbr ... returns
> "The sys_perf_event_open() syscall returned with 95 (Operation not
That is because it is only accepted for PERF_TYPE_HARDWARE on x86, i.e.
it retunrs EOPNOTSUPP for all the other cases, like for
PERF_TYPE_SOFTWARE counters, like "cpu-clock"
> supported) for event (cpu-clock).", so I'd guess not, although many
> other MSRs are exposed).
>
> BTS seemed more promising (deeper stacks), and there's already Xen
> support for it (need to boot the Xen host with vpmu=bts, preferably
> vpmu=bts,arch for some PMCs as well :).
Yeah, worth a look, I guess, but doesn't look like a low hanging fruit
tho.
- Arnaldo
next prev parent reply other threads:[~2016-04-27 12:56 UTC|newest]
Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-04-20 22:47 [PATCH/RFC] perf core: Allow setting up max frame stack depth via sysctl Arnaldo Carvalho de Melo
2016-04-20 23:04 ` Alexei Starovoitov
2016-04-22 20:52 ` [PATCH/RFC v2] " Arnaldo Carvalho de Melo
2016-04-22 21:37 ` Alexei Starovoitov
2016-04-22 22:05 ` David Ahern
2016-04-22 22:18 ` Alexei Starovoitov
2016-04-25 16:14 ` Arnaldo Carvalho de Melo
2016-04-25 16:27 ` Arnaldo Carvalho de Melo
2016-04-25 19:22 ` Arnaldo Carvalho de Melo
2016-04-25 20:06 ` Alexei Starovoitov
2016-04-25 20:17 ` Arnaldo Carvalho de Melo
2016-04-25 21:59 ` Alexei Starovoitov
2016-04-25 23:41 ` Arnaldo Carvalho de Melo
2016-04-26 0:07 ` Alexei Starovoitov
2016-04-26 0:29 ` [PATCH/RFC v3] " Arnaldo Carvalho de Melo
2016-04-26 0:44 ` Alexei Starovoitov
2016-04-26 0:47 ` Arnaldo Carvalho de Melo
2016-04-26 0:49 ` Brendan Gregg
2016-04-26 16:33 ` Arnaldo Carvalho de Melo
2016-04-26 16:45 ` David Ahern
2016-04-27 13:20 ` Arnaldo Carvalho de Melo
2016-04-26 20:02 ` Brendan Gregg
2016-04-26 21:05 ` Arnaldo Carvalho de Melo
2016-04-26 21:55 ` Peter Zijlstra
2016-04-27 12:53 ` Arnaldo Carvalho de Melo
2016-04-26 21:58 ` Brendan Gregg
2016-04-26 22:10 ` Peter Zijlstra
2016-04-27 12:56 ` Arnaldo Carvalho de Melo [this message]
2016-04-26 21:58 ` Frederic Weisbecker
2016-04-27 12:53 ` Arnaldo Carvalho de Melo
2016-04-27 16:09 ` Frederic Weisbecker
2016-04-27 16:27 ` David Ahern
2016-04-27 15:39 ` [tip:perf/core] " tip-bot for Arnaldo Carvalho de Melo
2016-04-20 23:10 ` [PATCH/RFC] " David Ahern
2016-04-21 0:18 ` Arnaldo Carvalho de Melo
2016-04-21 10:48 ` Peter Zijlstra
2016-04-21 15:17 ` Arnaldo Carvalho de Melo
2016-04-21 15:42 ` Arnaldo Carvalho de Melo
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