From: Tejun Heo <tj@kernel.org>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Namhyung Kim <namhyung@kernel.org>,
Ingo Molnar <mingo@kernel.org>,
Arnaldo Carvalho de Melo <acme@kernel.org>,
Jiri Olsa <jolsa@redhat.com>,
Alexander Shishkin <alexander.shishkin@linux.intel.com>,
Mark Rutland <mark.rutland@arm.com>,
Stephane Eranian <eranian@google.com>,
LKML <linux-kernel@vger.kernel.org>,
linux-perf-users@vger.kernel.org, Li Zefan <lizefan@huawei.com>,
Johannes Weiner <hannes@cmpxchg.org>,
Adrian Hunter <adrian.hunter@intel.com>
Subject: Re: [PATCH 1/9] perf/core: Add PERF_RECORD_CGROUP event
Date: Fri, 20 Dec 2019 07:16:22 -0800 [thread overview]
Message-ID: <20191220151622.GF2914998@devbig004.ftw2.facebook.com> (raw)
In-Reply-To: <20191220093335.GC2844@hirez.programming.kicks-ass.net>
On Fri, Dec 20, 2019 at 10:33:35AM +0100, Peter Zijlstra wrote:
> On Fri, Dec 20, 2019 at 01:32:45PM +0900, Namhyung Kim wrote:
> > To support cgroup tracking, add CGROUP event to save a link between
> > cgroup path and inode number. The attr.cgroup bit was also added to
> > enable cgroup tracking from userspace.
> >
> > This event will be generated when a new cgroup becomes active.
> > Userspace might need to synthesize those events for existing cgroups.
> >
> > Cc: Tejun Heo <tj@kernel.org>
> > Cc: Li Zefan <lizefan@huawei.com>
> > Cc: Johannes Weiner <hannes@cmpxchg.org>
> > Cc: Adrian Hunter <adrian.hunter@intel.com>
> > Signed-off-by: Namhyung Kim <namhyung@kernel.org>
>
> TJ, is this the right thing to do? ISTR you had concerns on this topic
> on the past.
Yeah, cgroup->id is now the same as ino (on 64bit ino matchines) and
fhandle and uniquely identifies a cgroup instance in that boot
instance. That said, id -> path mapping can be done from userspace by
passing the cgroup id to open_by_handle_at(2) and then reading the
symlink in /proc/self/fd, so this event isn't necessary per-se if the
goal is mapping back ids to paths.
Thanks.
--
tejun
next prev parent reply other threads:[~2019-12-20 15:16 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-12-20 4:32 [PATCHSET 0/9] perf: Improve cgroup profiling (v2) Namhyung Kim
2019-12-20 4:32 ` [PATCH 1/9] perf/core: Add PERF_RECORD_CGROUP event Namhyung Kim
2019-12-20 9:33 ` Peter Zijlstra
2019-12-20 11:28 ` Namhyung Kim
2019-12-20 11:50 ` Namhyung Kim
2019-12-20 15:16 ` Tejun Heo [this message]
2019-12-21 8:49 ` Namhyung Kim
2019-12-20 4:32 ` [PATCH 2/9] perf/core: Add PERF_SAMPLE_CGROUP feature Namhyung Kim
2019-12-20 9:36 ` Peter Zijlstra
2019-12-20 15:23 ` Tejun Heo
2019-12-20 16:48 ` Peter Zijlstra
2019-12-20 16:59 ` Tejun Heo
2019-12-20 4:32 ` [PATCH 3/9] perf tools: Basic support for CGROUP event Namhyung Kim
2019-12-20 4:32 ` [PATCH 4/9] perf tools: Maintain cgroup hierarchy Namhyung Kim
2019-12-20 4:32 ` [PATCH 5/9] perf report: Add 'cgroup' sort key Namhyung Kim
2019-12-20 4:32 ` [PATCH 6/9] perf record: Support synthesizing cgroup events Namhyung Kim
2019-12-20 4:32 ` [PATCH 7/9] perf record: Add --all-cgroups option Namhyung Kim
2019-12-20 4:32 ` [PATCH 8/9] perf top: " Namhyung Kim
2019-12-20 4:32 ` [PATCH 9/9] perf script: Add --show-cgroup-events option Namhyung Kim
-- strict thread matches above, loose matches on Subject: below --
2019-12-23 6:07 [PATCHSET 0/9] perf: Improve cgroup profiling (v3) Namhyung Kim
2019-12-23 6:07 ` [PATCH 1/9] perf/core: Add PERF_RECORD_CGROUP event Namhyung Kim
2020-01-07 12:51 ` Peter Zijlstra
2020-01-07 13:46 ` Namhyung Kim
2020-01-07 13:34 [PATCHSET 0/9] perf: Improve cgroup profiling (v4) Namhyung Kim
2020-01-07 13:34 ` [PATCH 1/9] perf/core: Add PERF_RECORD_CGROUP event Namhyung Kim
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