On Mon, Mar 12, 2018 at 09:59:43AM -0700, Song Liu wrote: > When a perf_event is attached to parent cgroup, it should count events > for all children cgroups: > > parent_group <---- perf_event > \ > - child_group <---- process(es) > > However, in our tests, we found this perf_event cannot report reliable > results. Here is an example case: > > # create cgroups > mkdir -p /sys/fs/cgroup/p/c > # start perf for parent group > perf stat -e instructions -G "p" > > # on another console, run test process in child cgroup: > stressapptest -s 2 -M 1000 & echo $! > /sys/fs/cgroup/p/c/cgroup.procs > > # after the test process is done, stop perf in the first console shows > > <not counted> instructions p > > The instruction should not be "not counted" as the process runs in the > child cgroup. > > We found this is because perf_event->cgrp and cpuctx->cgrp are not > identical, thus perf_event->cgrp are not updated properly. > > This patch fixes this by updating perf_cgroup properly for ancestor > cgroup(s). > > Signed-off-by: Song Liu <songliubrav...@fb.com> > Reported-by: Ephraim Park <ephiep...@fb.com>
Yeah, that looks about right, Thanks!
