[Devel] Re: [PATCH 4/4] cpuacct.stat: re-use scheduler statistics for the root cgroup

[KAMEZAWA Hiroyuki]

On Thu, 24 Nov 2011 23:33:26 -0200
Glauber Costa <glommer at parallels.com> wrote:

> Right now, after we collect tick statistics for user and system and store them
> in a well known location, we keep the same statistics again for cpuacct.
> Since cpuacct is hierarchical, the numbers for the root cgroup should be
> absolutely equal to the system-wide numbers.
> 
> So it would be better to just use it: this patch changes cpuacct accounting
> in a way that the cpustat statistics are kept in a struct kernel_cpustat percpu
> array. In the root cgroup case, we just point it to the main array. The rest of
> the hierarchy walk can be totally disabled later with a static branch - but I am
> not doing it here.
> 
> Signed-off-by: Glauber Costa <glommer at parallels.com>
> CC: Paul Tuner <pjt at google.com>
> CC: Peter Zijlstra <a.p.zijlstra at chello.nl>

seems reasonable to me.

Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu at jp.fujitsu.com>