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From: Namhyung Kim <namhyung@kernel.org>
To: Andi Kleen <andi@firstfloor.org>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>,
	Jiri Olsa <jolsa@redhat.com>, Ingo Molnar <mingo@kernel.org>,
	Peter Zijlstra <a.p.zijlstra@chello.nl>,
	Mark Rutland <mark.rutland@arm.com>,
	Alexander Shishkin <alexander.shishkin@linux.intel.com>,
	Stephane Eranian <eranian@google.com>,
	LKML <linux-kernel@vger.kernel.org>,
	Ian Rogers <irogers@google.com>
Subject: Re: [PATCHSET 0/4] perf stat: Add --multiply-cgroup option
Date: Fri, 11 Sep 2020 11:35:30 +0900	[thread overview]
Message-ID: <CAM9d7cjv3nXACmNLGW2kmgwvcWUJJnkaunQamB=J0GoUzwvYfg@mail.gmail.com> (raw)
In-Reply-To: <20200910155736.jadhmqvnqquammpn@two.firstfloor.org>

Hi Andi,

On Fri, Sep 11, 2020 at 1:05 AM Andi Kleen <andi@firstfloor.org> wrote:
>
> On Tue, Sep 08, 2020 at 01:42:24PM +0900, Namhyung Kim wrote:
> > When we profile cgroup events with perf stat, it's very annoying to
> > specify events and cgroups on the command line as it requires the
> > mapping between events and cgroups.  (Note that perf record can use
> > cgroup sampling but it's not usable for perf stat).
>
> The problem is real, but I don't really like your solution.
> The option is ugly. Should rather be solved with some suitable
> syntax in the expression parser to express: apply to all,
> instead of adding adhoc options like this.

Yeah, I'd admit that I'm terrible at naming. :)
I'm open to any suggestions as I'm also bad at making new syntax..

But as Ian said, my approach takes care of the common case
without dealing with controversial syntax changes.

>
> There are some additional problems that really need to be eventually
> solved too:
>
> - If you use the old syntax and some cgroups are not covered you don't
> get any warning. At least that should be fixed too.

I don't follow.  Do you mean like when -G option and --multiply-cgroup option
is used at the same time?  Or when -G option doesn't match to -e option?

>
> - And of course if everything works it is still very slow for the kernel
> because there are so many perf events to handle. Long term we probably
> need some more flexible way to just specify for given perf events which set of
> cgroups they should apply, so that sharing and low overhead monitoring
> of many cgroups is possible I hate to say it, but maybe some eBPF filter
> is the solution here.

Yes, I'm also interested in improving that too.

Thanks
Namhyung

      parent reply	other threads:[~2020-09-11  2:35 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-09-08  4:42 [PATCHSET 0/4] perf stat: Add --multiply-cgroup option Namhyung Kim
2020-09-08  4:42 ` [PATCH 1/4] perf evsel: Add evsel__clone() function Namhyung Kim
2020-09-10  8:59   ` Jiri Olsa
2020-09-10 13:18     ` Namhyung Kim
2020-09-08  4:42 ` [PATCH 2/4] perf stat: Add --multiply-cgroup option Namhyung Kim
2020-09-08  4:42 ` [PATCH 3/4] perf tools: Copy metric events properly when multiply cgroups Namhyung Kim
2020-09-23  9:14   ` [perf tools] 77b66fd551: perf-sanity-tests.'import_perf'_in_python.fail kernel test robot
2020-09-23  9:14     ` kernel test robot
2020-09-24  3:04     ` Namhyung Kim
2020-09-24  3:04       ` Namhyung Kim
2020-09-25 11:55       ` Arnaldo Carvalho de Melo
2020-09-25 11:55         ` Arnaldo Carvalho de Melo
2020-09-08  4:42 ` [PATCH 4/4] perf test: Add multiply cgroup event test Namhyung Kim
2020-09-10  9:15 ` [PATCHSET 0/4] perf stat: Add --multiply-cgroup option Jiri Olsa
2020-09-10 11:10   ` Arnaldo Carvalho de Melo
2020-09-10 13:32     ` Namhyung Kim
2020-09-10 15:57 ` Andi Kleen
2020-09-10 17:11   ` Ian Rogers
2020-09-11  2:54     ` Namhyung Kim
2020-09-11  2:35   ` Namhyung Kim [this message]

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