Re: [PATCH v3 12/12] cpuset: export effective masks to userspace

From: Tejun Heo
Date: Wed Jul 09 2014 - 16:24:18 EST


On Wed, Jul 09, 2014 at 04:15:49PM -0400, Tejun Heo wrote:
> On Wed, Jul 09, 2014 at 04:49:25PM +0800, Li Zefan wrote:
> > cpuset.cpus and cpuset.mems are the configured masks, and we need
> > to export effective masks to userspace, so users know the real
> > cpus_allowed and mems_allowed that apply to the tasks in a cpuset.
> >
> > v2:
> > - export those masks unconditionally, suggested by Tejun.
> >
> > Signed-off-by: Li Zefan <lizefan@xxxxxxxxxx>
>
> I applied this patch but there's a pending patchset to split legacy
> and dfl cftype arrays, so maybe doing it separately makes more sense
> now, I'm not sure. Anyways, we need to review cpuset interface for
> the default hierarchy anyway. At least the memory pressure knobs
> should go. It's measuring something which is completely
> implementation dependent.

The exclusive knobs too. These are purely to aid configuration.
memory_migrate is questionable too given that we're moving towards the
model where the controllers are set up before the cgroup gets
populated. Also, if necessary, this should be implementable from
userland with migrate_pages(2).

Thanks.

--
tejun
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