Re: [PATCH 10/11] Direct compact when a high-order allocation fails

[KAMEZAWA Hiroyuki]

On Thu, 25 Mar 2010 09:48:26 +0000
Mel Gorman <mel@xxxxxxxxx> wrote:

> > In that case, compact_finished() can't
> > find there is a free chunk and do more work.  How about using a function like
> > 	 free_pcppages_bulk(zone, pcp->batch, pcp);
> > to bypass pcp list and freeing pages at once ?
> > 
> 
> I think you mean to drain the PCP lists while compaction is happening
> but is it justified? It's potentially a lot of IPI calls just to check
> if compaction can finish a little earlier. If the pages on the PCP lists
> are making that much of a difference to high-order page availability, it
> implies that the zone is pretty full and it's likely that compaction was
> avoided and we direct reclaimed.
> 
Ah, sorry for my short word again. I mean draining "local" pcp list because
a thread which run direct-compaction freed pages. IPI is not necessary and
overkill.

Thanks,
-Kame

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