linux-kernel - Re: [PATCH] vmscan: bail out of page reclaim after swap_cluster

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Message-Id: <20081130150849.8140.KOSAKI.MOTOHIRO@jp.fujitsu.com>
Date:	Sun, 30 Nov 2008 15:30:51 +0900 (JST)
From:	KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>
To:	Rik van Riel <riel@...hat.com>
Cc:	kosaki.motohiro@...fujitsu.com, akpm@...ux-foundation.org,
	linux-mm@...ck.org, linux-kernel@...r.kernel.org, mel@....ul.ie
Subject: Re: [PATCH] vmscan: bail out of page reclaim after swap_cluster_max pages

> Reclaiming is very easy when the workload is just page cache,
> because the application will be throttled when too many page
> cache pages are dirty.
> 
> When using mmap or memory hogs writing to swap, applications
> will not be throttled by the "too many dirty pages" logic,
> but may instead end up being throttled in the direct reclaim
> path instead.
> 
> At that point direct reclaim may become a lot more common,
> making the imbalance more significant.

fair enough.


> I'll run a few tests.

Great.
I'm looking for your mail :)


> > Andrew, I hope add this mesurement result to rvr bailing out patch description too.
> 
> So far the performance numbers you have measured are very
> encouraging and do indeed suggest that the priority==DEF_PRIORITY
> thing does not make a difference.

thank you.

I believe reclaim latency reducing doesn't only improve hpc, but also
improve several multimedia and desktop application.



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