Messages in this thread | | | Date | Fri, 26 Nov 2010 09:50:24 +0800 | From | Li Zefan <> | Subject | Re: [PATCH 1/2] perf_events: add support for per-cpu per-cgroup monitoring (v5) |
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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 <eranian@google.com> > > 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.
> Also, it might make sense to add a CONFIG_PERF_CGROUP, even if you want > it automagically set if CONFIG_PERF && CONFIG_CGROUP, its easier to find > all related code if its under a single CONFIG_var. >
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