Re: [PATCH] cgroup: add tracepoints to track cgroup events

[Tejun Heo <tj@kernel.org>]

Hello, Anrea.

On Thu, Aug 21, 2014 at 11:00:02AM -0600, Andrea Righi wrote:
> hmm... am I missing something or we already support directory events?

Ah, right, those mkdir/rmdir and writes automatically generate those
events.

> root@Dell:~# grep cgroups /proc/mounts
> none /cgroups cgroup rw,relatime,cpuset,cpu,cpuacct,memory,devices,freezer,perf_event,hugetlb 0 0
> root@Dell:~# inotifywait -m -r -e modify -e move -e create -e delete /cgroups
> Setting up watches.  Beware: since -r was given, this may take a while!
> Watches established.
> /cgroups/ CREATE,ISDIR test
> /cgroups/test/ MODIFY cgroup.procs
> /cgroups/test/ MODIFY cgroup.procs
> /cgroups/test/ MODIFY cgroup.populated
> /cgroups/ MODIFY cgroup.procs
> /cgroups/ MODIFY cgroup.procs
> /cgroups/test/ MODIFY cgroup.populated
> /cgroups/ DELETE,ISDIR test
> 
> I still need to figure out a smart way to track which PIDs are
> added/removed to/from cgroup.procs from userland (inotifywait + git? :)),
> but all the other informations provided by my tracepoint patch seem to
> be already available via [di]notify.

Hmmm... yeah, determining exactly which pids got added / removed can
be cumbersome from just MODIFY events.  That said, what are you trying
to do with such information?

Thanks.

-- 
tejun