From mboxrd@z Thu Jan  1 00:00:00 1970
From: Peter Zijlstra <peterz-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org>
Subject: Re: [Lsf] [RFC] writeback and cgroup
Date: Sat, 14 Apr 2012 13:53:43 +0200
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To: Tejun Heo <tj-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
Cc: ctalbott-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org, rni-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org, andrea-oIIqvOZpAevzfdHfmsDf5w@public.gmane.org, containers-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, lsf-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org, linux-mm-Bw31MaZKKs3YtjvyW6yDsg@public.gmane.org, jmoyer-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org, linux-fsdevel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Vivek Goyal <vgoyal-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
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On Wed, 2012-04-04 at 11:49 -0700, Tejun Heo wrote:
> > - How to handle NFS.
> 
> As said above, maybe through network based bdi pressure propagation,
> Maybe some other special case mechanism.  Unsure but I don't think
> this concern should dictate the whole design. 

NFS has a custom bdi implementation and implements congestion control
based on the number of outstanding writeback pages.

See fs/nfs/write.c:nfs_{set,end}_page_writeback

All !block based filesystems have their own BDI implementation, I'm not
sure on the congestion implementation of anything other than NFS though.