Messages in this thread | | | Subject | Re: [PATCH 1/2] perf_events: add support for per-cpu per-cgroup monitoring (v5) | From | Peter Zijlstra <> | Date | Fri, 26 Nov 2010 12:17:36 +0100 |
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On Fri, 2010-11-26 at 08:26 +0530, Balbir Singh wrote: > * lizf@cn.fujitsu.com <lizf@cn.fujitsu.com> [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 <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.
egads, I knew I should have looked at that.. :/
> > 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.
You could of course have added an ID instead ;-)
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