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SubjectRe: [PATCH 1/4] vmscan: delegate pageout io to flusher thread if current is kswapd
Date
Cc to Johannes

> >
> > On Apr 14, 2010, at 9:11 PM, KOSAKI Motohiro wrote:
> >
> > > Now, vmscan pageout() is one of IO throuput degression source.
> > > Some IO workload makes very much order-0 allocation and reclaim
> > > and pageout's 4K IOs are making annoying lots seeks.
> > >
> > > At least, kswapd can avoid such pageout() because kswapd don't
> > > need to consider OOM-Killer situation. that's no risk.
> > >
> > > Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
> >
> > What's your opinion on trying to cluster the writes done by pageout,
> > instead of not doing any paging out in kswapd?
> > Something along these lines:
>
> Interesting.
> So, I'd like to review your patch carefully. can you please give me one
> day? :)

Hannes, if my remember is correct, you tried similar swap-cluster IO
long time ago. now I can't remember why we didn't merged such patch.
Do you remember anything?


>
>
> >
> > Cluster writes to disk due to memory pressure.
> >
> > Write out logically adjacent pages to the one we're paging out
> > so that we may get better IOs in these situations:
> > These pages are likely to be contiguous on disk to the one we're
> > writing out, so they should get merged into a single disk IO.
> >
> > Signed-off-by: Suleiman Souhlal <suleiman@google.com>
>
>
>
>





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