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From: Tejun Heo <tj@kernel.org>
To: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>,
	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>
Subject: Re: [PATCH 2/9] perf/core: Add PERF_SAMPLE_CGROUP feature
Date: Fri, 20 Dec 2019 07:23:24 -0800	[thread overview]
Message-ID: <20191220152324.GG2914998@devbig004.ftw2.facebook.com> (raw)
In-Reply-To: <20191220043253.3278951-3-namhyung@kernel.org>

On Fri, Dec 20, 2019 at 01:32:46PM +0900, Namhyung Kim wrote:
> The PERF_SAMPLE_CGROUP bit is to save (perf_event) cgroup information
> in the sample.  It will add a 64-bit id to identify current cgroup and
> it's the file handle in the cgroup file system.  Userspace should use
> this information with PERF_RECORD_CGROUP event to match which cgroup
> it belongs.

You don't need PERF_RECORD_CGROUP for that.  Something like the
following should work.

	struct {
		struct file_handle fh;
		char stor[MAX_HANDLE_SZ];
	} fh_store;
	struct file_handle *fh = &fh_store;

	fh->handle_type = 0xfe; // FILEID_KERNFS
	fh->handle_bytes = sizeof(u64);
	*(u64 *)fh->f_handle = cgrp_id;

	mnt_fd = open('/sys/fs/cgroup', O_RDONLY);
	fd = open_by_handle_at(mnt_fd, fh, O_RDONLY);

	snprintf(proc_path, PATH_MAX, "/proc/self/fd/%d", fd);
	readlink(proc_path, cgrp_path, PATH_MAX);

-- 
tejun

  parent reply	other threads:[~2019-12-20 15:23 UTC|newest]

Thread overview: 37+ 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
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 [this message]
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 --
2020-03-25 12:45 [PATCHSET 0/9] perf: Improve cgroup profiling (v6) Namhyung Kim
2020-03-25 12:45 ` [PATCH 2/9] perf/core: Add PERF_SAMPLE_CGROUP feature Namhyung Kim
2020-01-07 13:34 [PATCHSET 0/9] perf: Improve cgroup profiling (v4) Namhyung Kim
2020-01-07 13:34 ` [PATCH 2/9] perf/core: Add PERF_SAMPLE_CGROUP feature Namhyung Kim
2019-12-23  6:07 [PATCHSET 0/9] perf: Improve cgroup profiling (v3) Namhyung Kim
2019-12-23  6:07 ` [PATCH 2/9] perf/core: Add PERF_SAMPLE_CGROUP feature Namhyung Kim
2019-08-28  7:31 [PATCHSET 0/9] perf: Improve cgroup profiling (v1) Namhyung Kim
2019-08-28  7:31 ` [PATCH 2/9] perf/core: Add PERF_SAMPLE_CGROUP feature Namhyung Kim
2019-08-28 14:49   ` Tejun Heo
2019-08-31  3:03     ` Namhyung Kim
2019-08-31  4:58       ` Tejun Heo
2019-09-03  2:13         ` Namhyung Kim
2019-09-05 16:56           ` Tejun Heo
2019-09-08 13:28             ` Namhyung Kim
2019-09-14 14:02         ` Song Liu
2019-09-16 15:23           ` Tejun Heo
2019-09-19  6:42             ` Song Liu
2019-09-20  8:47               ` Namhyung Kim
2019-09-20 16:13                 ` Song Liu
2019-09-20 21:04                 ` Tejun Heo
2019-10-02  6:28                   ` Namhyung Kim
2019-10-07 14:16                     ` Tejun Heo

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