[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-ID: <8B2062CE-9BD5-4F17-B831-38C9274A1509@fb.com>
Date: Tue, 30 Mar 2021 06:33:16 +0000
From: Song Liu <songliubraving@...com>
To: Namhyung Kim <namhyung@...nel.org>
CC: Peter Zijlstra <peterz@...radead.org>,
Ingo Molnar <mingo@...nel.org>,
Arnaldo Carvalho de Melo <acme@...nel.org>,
Jiri Olsa <jolsa@...hat.com>,
Mark Rutland <mark.rutland@....com>,
Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
LKML <linux-kernel@...r.kernel.org>,
Stephane Eranian <eranian@...gle.com>,
Andi Kleen <ak@...ux.intel.com>,
"Ian Rogers" <irogers@...gle.com>, Tejun Heo <tj@...nel.org>
Subject: Re: [PATCH 1/2] perf/core: Share an event with multiple cgroups
> On Mar 29, 2021, at 4:33 AM, Namhyung Kim <namhyung@...nel.org> wrote:
>
> On Mon, Mar 29, 2021 at 2:17 AM Song Liu <songliubraving@...com> wrote:
>>> On Mar 23, 2021, at 9:21 AM, Namhyung Kim <namhyung@...nel.org> wrote:
>>>
>>> As we can run many jobs (in container) on a big machine, we want to
>>> measure each job's performance during the run. To do that, the
>>> perf_event can be associated to a cgroup to measure it only.
>>>
[...]
>>> + return 0;
>>> +}
>>
>> Could you please explain why we need this logic in can_attach?
>
> IIUC the ss->attach() is called after a task's cgroup membership
> is changed. But we want to collect the performance numbers for
> the old cgroup just before the change. As the logic merely checks
> the current task's cgroup, it should be done in the can_attach()
> which is called before the cgroup change.
Thanks for the explanations.
Overall, I really like the core idea, especially that the overhead on
context switch is bounded (by the depth of cgroup tree).
Is it possible to make PERF_EVENT_IOC_ATTACH_CGROUP more flexible?
Specifically, if we can have
PERF_EVENT_IOC_ADD_CGROUP add a cgroup to the list
PERF_EVENT_IOC_EL_CGROUP delete a cgroup from the list
we can probably share these events among multiple processes, and
these processes don't need to know others' cgroup list. I think
this will be useful for users to build customized monitoring in
its own container.
Does this make sense?
Thanks,
Song
Powered by blists - more mailing lists