From: Arnaldo Carvalho de Melo <acme@kernel.org>
To: Song Liu <songliubraving@fb.com>
Cc: Namhyung Kim <namhyung@kernel.org>, 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: Tue, 23 Mar 2021 18:10:22 -0300 [thread overview]
Message-ID: <YFpZPijlMSyfIVbl@kernel.org> (raw)
In-Reply-To: <EC00E37D-8587-4662-8E30-7AD5F874FA84@fb.com>
Em Fri, Mar 19, 2021 at 04:14:42PM +0000, Song Liu escreveu:
> > On Mar 19, 2021, at 8:58 AM, Namhyung Kim <namhyung@kernel.org> wrote:
> > On Sat, Mar 20, 2021 at 12:35 AM Arnaldo Carvalho de Melo <acme@kernel.org> wrote:
> >> 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:
> > I have a concern for the per cpu target, but it can be done later, so
> > Acked-by: Namhyung Kim <namhyung@kernel.org>
> >> https://git.kernel.org/pub/scm/linux/kernel/git/acme/linux.git/log/?h=tmp.bpf/bpf_perf_enable
> > Interesting! Actually I was thinking about the similar too. :)
>
> Hi Namhyung, Jiri, and Arnaldo,
>
> Thanks a lot for your kind review.
>
> Here is updated 3/3, where we use perf-bench instead of stressapptest.
I had to apply this updated 3/3 manually, as there was some munging, its
all now at:
https://git.kernel.org/pub/scm/linux/kernel/git/acme/linux.git/log/?h=tmp.perf/core
Please take a look at the "Committer testing" section I added to the
main patch, introducing bperf:
https://git.kernel.org/pub/scm/linux/kernel/git/acme/linux.git/commit/?h=tmp.perf/core&id=7fac83aaf2eecc9e7e7b72da694c49bb4ce7fdfc
And check if I made any mistake or if something else could be added.
It'll move to perf/core after my set of automated tests finishes.
- Arnaldo
next prev parent reply other threads:[~2021-03-23 21:11 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
2021-03-19 15:58 ` Namhyung Kim
2021-03-19 16:14 ` Song Liu
2021-03-23 21:10 ` Arnaldo Carvalho de Melo [this message]
2021-03-23 21:26 ` Song Liu
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