linux-kernel - Re: [PATCH 0/9] Reduce latencies and improve overall reclaim efficiency v1

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Message-Id: <20100908115807.C916.A69D9226@jp.fujitsu.com>
Date:	Wed,  8 Sep 2010 12:14:29 +0900 (JST)
From:	KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>
To:	Mel Gorman <mel@....ul.ie>
Cc:	kosaki.motohiro@...fujitsu.com, linux-mm@...ck.org,
	linux-fsdevel@...r.kernel.org,
	Linux Kernel List <linux-kernel@...r.kernel.org>,
	Rik van Riel <riel@...hat.com>,
	Johannes Weiner <hannes@...xchg.org>,
	Minchan Kim <minchan.kim@...il.com>,
	Wu Fengguang <fengguang.wu@...el.com>,
	Andrea Arcangeli <aarcange@...hat.com>,
	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>,
	Dave Chinner <david@...morbit.com>,
	Chris Mason <chris.mason@...cle.com>,
	Christoph Hellwig <hch@....de>,
	Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: [PATCH 0/9] Reduce latencies and improve overall reclaim efficiency v1

> There have been numerous reports of stalls that pointed at the problem being
> somewhere in the VM. There are multiple roots to the problems which means
> dealing with any of the root problems in isolation is tricky to justify on
> their own and they would still need integration testing. This patch series
> gathers together three different patch sets which in combination should
> tackle some of the root causes of latency problems being reported.
> 
> The first patch improves vmscan latency by tracking when pages get reclaimed
> by shrink_inactive_list. For this series, the most important results is
> being able to calculate the scanning/reclaim ratio as a measure of the
> amount of work being done by page reclaim.
> 
> Patches 2 and 3 account for the time spent in congestion_wait() and avoids
> calling going to sleep on congestion when it is unnecessary. This is expected
> to reduce stalls in situations where the system is under memory pressure
> but not due to congestion.
> 
> Patches 4-8 were originally developed by Kosaki Motohiro but reworked for
> this series. It has been noted that lumpy reclaim is far too aggressive and
> trashes the system somewhat. As SLUB uses high-order allocations, a large
> cost incurred by lumpy reclaim will be noticeable. It was also reported
> during transparent hugepage support testing that lumpy reclaim was trashing
> the system and these patches should mitigate that problem without disabling
> lumpy reclaim.

Wow, I'm sorry my lazyness bother you. I'll join to test this patch series
ASAP and take a feedback soon.




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