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From: Mel Gorman <mel@csn.ul.ie>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org,
	kamezawa.hiroyu@jp.fujitsu.com, clameter@sgi.com
Subject: Re: [PATCH 7/7] Compact memory directly by a process when a high-order allocation fails
Date: Thu, 21 Jun 2007 14:26:32 +0100	[thread overview]
Message-ID: <467A7C88.2040102@csn.ul.ie> (raw)
In-Reply-To: <20070621052813.ac93e12e.akpm@linux-foundation.org>

Andrew Morton wrote:
>> On Mon, 18 Jun 2007 10:30:42 +0100 (IST) Mel Gorman <mel@csn.ul.ie> wrote:
>> +
>> +			/*
>> +			 * It's a race if compaction frees a suitable page but
>> +			 * someone else allocates it
>> +			 */
>> +			count_vm_event(COMPACTRACE);
>> +		}
> 
> Could perhaps cause arbitrarily long starvation. 

More likely it will just fail allocations where it could have succeeded.
I knew the situation would occur so I thought I would count how often it
happens before doing.

> A fix would be to free
> the synchronously-compacted higher-order page into somewhere which is
> private to this task (a new field in task_struct would be one such place).

There used to be such fields and a process flag PF_FREE_PAGES for a
similar purpose. I'll look into reintroducing it. Thanks

-- 
Mel Gorman

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  reply	other threads:[~2007-06-21 13:26 UTC|newest]

Thread overview: 26+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2007-06-18  9:28 [PATCH 0/7] Memory Compaction v2 Mel Gorman
2007-06-18  9:28 ` [PATCH 1/7] KAMEZAWA Hiroyuki hot-remove patches Mel Gorman
2007-06-18 16:56   ` Christoph Lameter
2007-06-19 15:52     ` Mel Gorman
2007-06-18  9:29 ` [PATCH 2/7] Allow CONFIG_MIGRATION to be set without CONFIG_NUMA Mel Gorman
2007-06-18 17:04   ` Christoph Lameter
2007-06-19 15:59     ` Mel Gorman
2007-06-18  9:29 ` [PATCH 3/7] Introduce isolate_lru_page_nolock() as a lockless version of isolate_lru_page() Mel Gorman
2007-06-18 17:05   ` Christoph Lameter
2007-06-18  9:29 ` [PATCH 4/7] Provide metrics on the extent of fragmentation in zones Mel Gorman
2007-06-18 17:07   ` Christoph Lameter
2007-06-18  9:30 ` [PATCH 5/7] Introduce a means of compacting memory within a zone Mel Gorman
2007-06-18 17:18   ` Christoph Lameter
2007-06-19 16:36     ` Mel Gorman
2007-06-19 19:20       ` Christoph Lameter
2007-06-19 12:54   ` Yasunori Goto
2007-06-19 16:49     ` Mel Gorman
2007-06-18  9:30 ` [PATCH 6/7] Add /proc/sys/vm/compact_node for the explicit compaction of a node Mel Gorman
2007-06-18  9:30 ` [PATCH 7/7] Compact memory directly by a process when a high-order allocation fails Mel Gorman
2007-06-18 17:22   ` Christoph Lameter
2007-06-19 16:50     ` Mel Gorman
2007-06-21 12:28   ` Andrew Morton
2007-06-21 13:26     ` Mel Gorman [this message]
2007-06-18 17:24 ` [PATCH 0/7] Memory Compaction v2 Christoph Lameter
2007-06-19 16:58   ` Mel Gorman
2007-06-19 19:22     ` Christoph Lameter

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