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    SubjectRe: [PATCH 1/2] perf_events: add support for per-cpu per-cgroup monitoring (v5)
    Balbir Singh wrote:
    > * <> [2010-11-26 09:50:24]:
    >> 19:28, Peter Zijlstra wrote:
    >>> On Thu, 2010-11-18 at 12:40 +0200, Stephane Eranian wrote:
    >>>> This kernel patch adds the ability to filter monitoring based on
    >>>> container groups (cgroups). This is for use in per-cpu mode only.
    >>>> The cgroup to monitor is passed as a file descriptor in the pid
    >>>> argument to the syscall. The file descriptor must be opened to
    >>>> the cgroup name in the cgroup filesystem. For instance, if the
    >>>> cgroup name is foo and cgroupfs is mounted in /cgroup, then the
    >>>> file descriptor is opened to /cgroup/foo. Cgroup mode is
    >>>> activated by passing PERF_FLAG_PID_CGROUP in the flags argument
    >>>> to the syscall.
    >>>> For instance to measure in cgroup foo on CPU1 assuming
    >>>> cgroupfs is mounted under /cgroup:
    >>>> struct perf_event_attr attr;
    >>>> int cgroup_fd, fd;
    >>>> cgroup_fd = open("/cgroup/foo", O_RDONLY);
    >>>> fd = perf_event_open(&attr, cgroup_fd, 1, -1, PERF_FLAG_PID_CGROUP);
    >>>> close(cgroup_fd);
    >>>> Signed-off-by: Stephane Eranian <>
    >>> Could you please split this patch:
    >>> - pure code movement
    >>> - time accounting changes
    >>> - event_filter_match() stuff
    >>> - cgroup thing
    >>> From a quick reading it doesn't look bad, but I want an ACK from the
    >>> cgroup people -- specifically if they're OK with the filedesc juggling
    >>> thing, because I know the sysfs people objected to such tricks.
    >> Long long ago, a feature that used this trick was accepted, and that's
    >> cgroup taskstat.
    >> You get an fd of a cgroup directory and send it to the kernel via netlink,
    >> and then you'll receive some statistics, such as how many tasks are
    >> running/interrupted in that cgroup.
    > That is right, since cgroups don't have id's there is no easy way to
    > identify them, looking them up by name and passing strings seemed an
    > overkill.

    More information:

    Another feature recently added (eventfd-based notifications) also uses fd
    to identify a cgroup.

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      Last update: 2010-11-26 09:37    [W:0.023 / U:4.752 seconds]
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