From: Arnaldo Carvalho de Melo <acme@kernel.org>
To: Namhyung Kim <namhyung@kernel.org>
Cc: Song Liu <songliubraving@fb.com>, Jiri Olsa <jolsa@redhat.com>,
linux-kernel <linux-kernel@vger.kernel.org>,
Kernel Team <Kernel-team@fb.com>, Jiri Olsa <jolsa@kernel.org>
Subject: Re: [PATCH v2 0/3] perf-stat: share hardware PMCs with BPF
Date: Fri, 19 Mar 2021 12:35:12 -0300 [thread overview]
Message-ID: <YFTEsOhbx4Il1nji@kernel.org> (raw)
In-Reply-To: <CAM9d7ch_axD_4E0W7MEx8ueeq9QsvhxNWaJ0J3AtVgeKqKQmbA@mail.gmail.com>
Em Fri, Mar 19, 2021 at 09:54:59AM +0900, Namhyung Kim escreveu:
> On Fri, Mar 19, 2021 at 9:22 AM Song Liu <songliubraving@fb.com> wrote:
> > > On Mar 18, 2021, at 5:09 PM, Arnaldo <arnaldo.melo@gmail.com> wrote:
> > > On March 18, 2021 6:14:34 PM GMT-03:00, Jiri Olsa <jolsa@redhat.com> wrote:
> > >> On Thu, Mar 18, 2021 at 03:52:51AM +0000, Song Liu wrote:
> > >>> perf stat -C 1,3,5 107.063 [sec]
> > >>> perf stat -C 1,3,5 --bpf-counters 106.406 [sec]
> > >> I can't see why it's actualy faster than normal perf ;-)
> > >> would be worth to find out
> > > Isn't this all about contended cases?
> > Yeah, the normal perf is doing time multiplexing; while --bpf-counters
> > doesn't need it.
> Yep, so for uncontended cases, normal perf should be the same as the
> baseline (faster than the bperf). But for contended cases, the bperf
> works faster.
The difference should be small enough that for people that use this in a
machine where contention happens most of the time, setting a
~/.perfconfig to use it by default should be advantageous, i.e. no need
to use --bpf-counters on the command line all the time.
So, Namhyung, can I take that as an Acked-by or a Reviewed-by? I'll take
a look again now but I want to have this merged on perf/core so that I
can work on a new BPF SKEL to use this:
https://git.kernel.org/pub/scm/linux/kernel/git/acme/linux.git/log/?h=tmp.bpf/bpf_perf_enable
:-)
- Arnaldo
next prev parent reply other threads:[~2021-03-19 15:36 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-16 21:18 [PATCH v2 0/3] perf-stat: share hardware PMCs with BPF Song Liu
2021-03-16 21:18 ` [PATCH v2 1/3] perf-stat: introduce bperf, " Song Liu
2021-03-18 5:54 ` Namhyung Kim
2021-03-18 7:22 ` Song Liu
2021-03-18 13:49 ` Namhyung Kim
2021-03-18 17:16 ` Song Liu
2021-03-18 21:15 ` Jiri Olsa
2021-03-19 18:41 ` Arnaldo Carvalho de Melo
2021-03-19 18:55 ` Jiri Olsa
2021-03-19 22:06 ` Song Liu
2021-03-23 0:53 ` Song Liu
2021-03-23 12:25 ` Arnaldo Carvalho de Melo
2021-03-23 12:37 ` Arnaldo Carvalho de Melo
2021-03-23 18:27 ` Arnaldo Carvalho de Melo
2021-03-16 21:18 ` [PATCH v2 2/3] perf-stat: measure t0 and ref_time after enable_counters() Song Liu
2021-03-16 21:18 ` [PATCH v2 3/3] perf-test: add a test for perf-stat --bpf-counters option Song Liu
2021-03-18 6:07 ` Namhyung Kim
2021-03-18 7:39 ` Song Liu
2021-03-17 5:29 ` [PATCH v2 0/3] perf-stat: share hardware PMCs with BPF Namhyung Kim
2021-03-17 9:19 ` Jiri Olsa
2021-03-17 13:11 ` Arnaldo Carvalho de Melo
2021-03-18 3:52 ` Song Liu
2021-03-18 4:32 ` Namhyung Kim
2021-03-18 7:03 ` Song Liu
2021-03-18 21:14 ` Jiri Olsa
2021-03-19 0:09 ` Arnaldo
2021-03-19 0:22 ` Song Liu
2021-03-19 0:54 ` Namhyung Kim
2021-03-19 15:35 ` Arnaldo Carvalho de Melo [this message]
2021-03-19 15:58 ` Namhyung Kim
2021-03-19 16:14 ` Song Liu
2021-03-23 21:10 ` Arnaldo Carvalho de Melo
2021-03-23 21:26 ` Song Liu
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