linux-kernel - Re: [PATCH] vmscan: recalculate lru

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Message-Id: <20100628103828.3873.A69D9226@jp.fujitsu.com>
Date:	Mon, 28 Jun 2010 10:39:40 +0900 (JST)
From:	KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>
To:	Johannes Weiner <hannes@...xchg.org>
Cc:	kosaki.motohiro@...fujitsu.com,
	LKML <linux-kernel@...r.kernel.org>,
	linux-mm <linux-mm@...ck.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Rik van Riel <riel@...hat.com>,
	Minchan Kim <minchan.kim@...il.com>
Subject: Re: [PATCH] vmscan: recalculate lru_pages on each priority

> On Fri, Jun 25, 2010 at 06:13:20PM +0900, KOSAKI Motohiro wrote:
> > shrink_zones() need relatively long time. and lru_pages can be
> > changed dramatically while shrink_zones().
> > then, lru_pages need recalculate on each priority.
> 
> In the direct reclaim path, we bail out of that loop after
> SWAP_CLUSTER_MAX reclaimed pages, so in this case, decreasing priority
> levels actually mean we do _not_ make any progress and the total
> number of lru pages should not change (much).  The possible distortion
> in shrink_slab() is small.

Oh, you seems forgot the case when much thread enter try_to_free_pages()
concurrently.

> 
> However, for the suspend-to-disk case the reclaim target can be a lot
> higher and we inevitably end up at higher priorities even though we
> make progress, but fail to increase pressure on the shrinkers as well
> without your patch.
> 
> Acked-by: Johannes Weiner <hannes@...xchg.org>



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