Re: [Lsf-pc] [LSF/MM ATTEND] Filesystems -- Btrfs, cgroups, Storage topics from Facebook

[Jan Kara <jack@suse.cz>]

On Tue 31-12-13 16:49:27, Zheng Liu wrote:
> Hi Chris,
> 
> On Mon, Dec 30, 2013 at 09:36:20PM +0000, Chris Mason wrote:
> > Hi everyone,
> > 
> > I'd like to attend the LSF/MM conference this year.  My current
> > discussion points include:
> > 
> > All things Btrfs!
> > 
> > Adding cgroups for more filesystem resources, especially to limit the
> > speed dirty pages are created.
> 
> Interesting.  If I remember correctly, IO-less dirty throttling has been
> applied into upstream kernel, which can limit the speed that dirty pages
> are created.  Does it has any defect?
  It works as it should. But as Jeff points out, the throttling isn't
cgroup aware. So it can happen that one memcg is full of dirty pages and
reclaim has problems with reclaiming pages for it. I guess what Chris asks
for is that we watch number of dirty pages in each memcg and throttle
processes creating dirty pages in memcg which is close to its limit on
dirty pages.

								Honza
-- 
Jan Kara <jack@suse.cz>
SUSE Labs, CR