Re: [PATCH 5/7] cgroups: Ability to stop res charge propagation on bounded ancestor

KAMEZAWA Hiroyuki
2011-07-12T00:18:42Z

On Mon, 11 Jul 2011 16:15:04 +0200
Frederic Weisbecker <fweisbec@gmail.com> wrote:

> Moving a task from a cgroup to another may require to substract
> its resource charge from the old cgroup and add it to the new one.
>
> For this to happen, the uncharge/charge propagation can just stop
> when we reach the common ancestor for the two cgroups. Further
> the performance reasons, we also want to avoid to temporarily
> overload the common ancestors with a non-accurate resource
> counter usage if we charge first the new cgroup and uncharge the
> old one thereafter. This is going to be a requirement for the coming
> max number of task subsystem.
>
> To solve this, provide a pair of new API that can charge/uncharge
> a resource counter until we reach a given ancestor.
>
> Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
> Cc: Paul Menage <menage@google.com>
> Cc: Li Zefan <lizf@cn.fujitsu.com>
> Cc: Johannes Weiner <hannes@cmpxchg.org>
> Cc: Aditya Kali <adityakali@google.com>

Hmm, do you have the number to show the benefit of this new function ?
And....tasks is moving among cgroups so frequently as to show the benefit
of this function in your environment ??

Thanks,
-Kame