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From: Johannes Weiner <hannes@cmpxchg.org>
To: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: LKML <linux-kernel@vger.kernel.org>,
	linux-mm <linux-mm@kvack.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	Rik van Riel <riel@redhat.com>,
	Minchan Kim <minchan.kim@gmail.com>
Subject: Re: [PATCH] vmscan: recalculate lru_pages on each priority
Date: Sun, 27 Jun 2010 13:34:23 +0200	[thread overview]
Message-ID: <20100627113422.GA14504@cmpxchg.org> (raw)
In-Reply-To: <20100625181221.805A.A69D9226@jp.fujitsu.com>

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.

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@cmpxchg.org>

WARNING: multiple messages have this Message-ID (diff)
From: Johannes Weiner <hannes@cmpxchg.org>
To: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: LKML <linux-kernel@vger.kernel.org>,
	linux-mm <linux-mm@kvack.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	Rik van Riel <riel@redhat.com>,
	Minchan Kim <minchan.kim@gmail.com>
Subject: Re: [PATCH] vmscan: recalculate lru_pages on each priority
Date: Sun, 27 Jun 2010 13:34:23 +0200	[thread overview]
Message-ID: <20100627113422.GA14504@cmpxchg.org> (raw)
In-Reply-To: <20100625181221.805A.A69D9226@jp.fujitsu.com>

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.

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@cmpxchg.org>

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  parent reply	other threads:[~2010-06-27 11:34 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-06-25  9:13 [PATCH] vmscan: recalculate lru_pages on each priority KOSAKI Motohiro
2010-06-25  9:13 ` KOSAKI Motohiro
2010-06-25 14:15 ` Rik van Riel
2010-06-25 14:15   ` Rik van Riel
2010-06-26 23:33 ` Minchan Kim
2010-06-26 23:33   ` Minchan Kim
2010-06-27 11:34 ` Johannes Weiner [this message]
2010-06-27 11:34   ` Johannes Weiner
2010-06-28  1:39   ` KOSAKI Motohiro
2010-06-28  1:39     ` KOSAKI Motohiro

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