Re: [PATCH 5/6 v4] cfq-iosched: CFQ group hierarchical scheduling anduse_hierarchy interface

[Divyesh Shah]

On Tue, Feb 15, 2011 at 5:44 PM, Gui Jianfeng
<guijianfeng@xxxxxxxxxxxxxx> wrote:
> Hmm, it seems memcg aggregating stats in parent group.
> But do we really need to do that in kernel? I think it's easier to do it in
> userland, and it makes kernel much simpler.
>

I would prefer having stats aggregated up the hierarchy. One trick we
used at Google earlier was to do lazy updates for most stats. So we
would accumulate stats for a given timeslice and at the end of that
timeslice propagate those counts all the way up to the parent. For
device info like this, the update can be instantaneous since its not a
very frequent event. It would also be very useful to distinguish
between stats for the cgroup itself vs total values accumulated from
the subtree rooted at that cgroup like memcg does.

-- 
Thanks,
Divyesh
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/