Messages in this thread | | | Date | Wed, 5 Nov 2008 10:31:23 +0900 | From | KAMEZAWA Hiroyuki <> | Subject | Re: [patch 0/7] cpuset writeback throttling |
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On Tue, 4 Nov 2008 15:36:10 -0800 Andrew Morton <akpm@linux-foundation.org> wrote:
> On Tue, 4 Nov 2008 16:52:48 -0600 (CST) > Christoph Lameter <cl@linux-foundation.org> wrote: > > > On Tue, 4 Nov 2008, Andrew Morton wrote: > > > > > To fix this with a memcg-based throttling, the operator would need to > > > be able to create memcg's which have pages only from particular nodes. > > > (That's a bit indirect relative to what they want to do, but is > > > presumably workable). > > > > The system would need to have the capability to find the memcg groups that > > have dirty pages for a certain inode. Files are not constrained to nodes > > or memcg groups. > > Ah, we're talking about different things. > > In a memcg implementation what we would implement is "throttle > page-dirtying tasks in this memcg when the memcg's dirty memory reaches > 40% of its total". > yes. Andrea posted that.
> But that doesn't solve the problem which this patchset is trying to > solve, which is "don't let all the memory in all this group of nodes > get dirty". > yes. but this patch doesn't help the case you mentioned below.
> > 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.
/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.
Thanks, -Kame
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