From: Christoph Lameter <cl@linux.com>
To: Mel Gorman <mgorman@suse.de>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Minchan Kim <minchan.kim@gmail.com>,
KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/2] mm: page allocator: Initialise ZLC for first zone eligible for zone_reclaim
Date: Wed, 20 Jul 2011 14:52:15 -0500 (CDT) [thread overview]
Message-ID: <alpine.DEB.2.00.1107201443400.1472@router.home> (raw)
In-Reply-To: <alpine.DEB.2.00.1107201425200.1472@router.home>
The existing way of deciding if watermarks have been met looks broken to
me.
There are two pools of pages: One is the pages available from the buddy
lists and another the pages in the per cpu lists.
zone_watermark_ok() only checks those in the buddy lists
(NR_FREE_PAGES) is not updated when we get a page from the per cpu lists).
And we do check zone_watermark_ok() before even attempting to allocate
pages that may be available from the per cpu lists?
So the allocator may pass on a zone and/or go into reclaim despite of the
availability of pages on per cpu lists. The more pages one puts into the
per cpu lists the higher the chance of an OOM. ... Ok that is not true
since we flush the per cpu pages and get them back into the buddy lists
before that happens.
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next prev parent reply other threads:[~2011-07-20 19:52 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-07-15 15:08 [PATCH 0/2] Reduce frequency of stalls due to zone_reclaim() on NUMA v2r1 Mel Gorman
2011-07-15 15:08 ` [PATCH 1/2] mm: page allocator: Initialise ZLC for first zone eligible for zone_reclaim Mel Gorman
2011-07-18 14:56 ` Christoph Lameter
2011-07-18 16:05 ` Mel Gorman
2011-07-18 17:20 ` Christoph Lameter
2011-07-18 21:13 ` Mel Gorman
2011-07-18 21:54 ` Christoph Lameter
2011-07-19 14:01 ` Christoph Lameter
2011-07-20 18:08 ` Christoph Lameter
2011-07-20 19:18 ` Mel Gorman
2011-07-20 19:28 ` Christoph Lameter
2011-07-20 19:52 ` Christoph Lameter [this message]
2011-07-20 21:17 ` Christoph Lameter
2011-07-20 22:48 ` Mel Gorman
2011-07-21 15:24 ` Christoph Lameter
2011-07-15 15:09 ` [PATCH 2/2] mm: page allocator: Reconsider zones for allocation after direct reclaim Mel Gorman
2011-07-19 11:46 ` [PATCH] mm: page allocator: Reconsider zones for allocation after direct reclaim fix Mel Gorman
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