Re: [patch 0/7] cpuset writeback throttling

[Andrew Morton <akpm@linux-foundation.org>]

On Wed, 5 Nov 2008 10:31:23 +0900 KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> wrote:

> > 
> > Yes?  Someone help me out here.  I don't yet have my head around the
> > overlaps and incompatibilities here.  Perhaps the containers guys will
> > wake up and put their thinking caps on?
> > 
> > 
> > 
> > What happens if cpuset A uses nodes 0,1,2,3,4,5,6,7,8,9 and cpuset B
> > uses nodes 0,1?  Can activity in cpuset A cause ooms in cpuset B?
> > 
> For help this, per-node-dirty-ratio-throttoling is necessary.
> 
> Shouldn't we just have a new parameter as /proc/sys/vm/dirty_ratio_per_node.

I guess that would work.  But it is a general solution and will be less
efficient for the particular setups which are triggering this problem.

> /proc/sys/vm/dirty_ratio works for throttling the whole system dirty pages.
> /proc/sys/vm/dirty_ratio_per_node works for throttling dirty pages in a node.
> 
> Implementation will not be difficult and works enough against OOM.

Yup.  Just track per-node dirtiness and walk the LRU when it is over
threshold.