From: Christian Ehrhardt <ehrhardt@linux.vnet.ibm.com>
To: Mel Gorman <mel@csn.ul.ie>
Cc: Andrew Morton <akpm@linux-foundation.org>,
linux-mm@kvack.org, Nick Piggin <npiggin@suse.de>,
Chris Mason <chris.mason@oracle.com>,
Jens Axboe <jens.axboe@oracle.com>,
linux-kernel@vger.kernel.org
Subject: Re: [RFC PATCH 0/3] Avoid the use of congestion_wait under zone pressure
Date: Fri, 12 Mar 2010 13:15:05 +0100 [thread overview]
Message-ID: <4B9A3049.7010602@linux.vnet.ibm.com> (raw)
In-Reply-To: <20100312104712.GB18274@csn.ul.ie>
Mel Gorman wrote:
> On Fri, Mar 12, 2010 at 02:05:26AM -0500, Andrew Morton wrote:
>> On Fri, 12 Mar 2010 07:39:26 +0100 Christian Ehrhardt <ehrhardt@linux.vnet.ibm.com> wrote:
>>
>>>
>>> Andrew Morton wrote:
>>>> On Mon, 8 Mar 2010 11:48:20 +0000
>>>> Mel Gorman <mel@csn.ul.ie> wrote:
[...]
>> If not, we broke it again.
>>
>
> We were broken with respect to this in the first place. That
> cond_reched() is badly placed and waiting on congestion when congestion
> might not be involved is also a bit odd.
>
> It's possible that Christian's specific problem would also be addressed
> by the following patch. Christian, willing to test?
Will is here, but no chance before monday/tuesday to get a free machine
slot - I'll post results as soon as I get them.
> It still feels a bit unnatural though that the page allocator waits on
> congestion when what it really cares about is watermarks. Even if this
> patch works for Christian, I think it still has merit so will kick it a
> few more times.
In whatever way I can look at it watermark_wait should be supperior to
congestion_wait. Because as Mel points out waiting for watermarks is
what is semantically correct there.
If there eventually some day comes a solution without any of those waits
I'm fine too - e.g. by closing whatever races we have and fixing that
one context can never run into this in direct_reclaim:
1. free pages with try_to_free
2. not getting one in the subsequent get_page call
But as long as we have a wait - watermark waiting > congestion waiting
(IMHO).
> ==== CUT HERE ====
> page-allocator: Attempt page allocation immediately after direct reclaim
[...]
--
Grusse / regards, Christian Ehrhardt
IBM Linux Technology Center, System z Linux Performance
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next prev parent reply other threads:[~2010-03-12 12:15 UTC|newest]
Thread overview: 68+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-03-08 11:48 [RFC PATCH 0/3] Avoid the use of congestion_wait under zone pressure Mel Gorman
2010-03-08 11:48 ` [PATCH 1/3] page-allocator: Under memory pressure, wait on pressure to relieve instead of congestion Mel Gorman
2010-03-09 13:35 ` Nick Piggin
2010-03-09 14:17 ` Mel Gorman
2010-03-09 15:03 ` Nick Piggin
2010-03-09 15:42 ` Christian Ehrhardt
2010-03-09 18:22 ` Mel Gorman
2010-03-10 2:38 ` Nick Piggin
2010-03-09 17:35 ` Mel Gorman
2010-03-10 2:35 ` Nick Piggin
2010-03-09 15:50 ` Christoph Lameter
2010-03-09 15:56 ` Christian Ehrhardt
2010-03-09 16:09 ` Christoph Lameter
2010-03-09 17:01 ` Mel Gorman
2010-03-09 17:11 ` Christoph Lameter
2010-03-09 17:30 ` Mel Gorman
2010-03-08 11:48 ` [PATCH 2/3] page-allocator: Check zone pressure when batch of pages are freed Mel Gorman
2010-03-09 9:53 ` Nick Piggin
2010-03-09 10:08 ` Mel Gorman
2010-03-09 10:23 ` Nick Piggin
2010-03-09 10:36 ` Mel Gorman
2010-03-09 11:11 ` Nick Piggin
2010-03-09 11:29 ` Mel Gorman
2010-03-08 11:48 ` [PATCH 3/3] vmscan: Put kswapd to sleep on its own waitqueue, not congestion Mel Gorman
2010-03-09 10:00 ` Nick Piggin
2010-03-09 10:21 ` Mel Gorman
2010-03-09 10:32 ` Nick Piggin
2010-03-11 23:41 ` [RFC PATCH 0/3] Avoid the use of congestion_wait under zone pressure Andrew Morton
2010-03-12 6:39 ` Christian Ehrhardt
2010-03-12 7:05 ` Andrew Morton
2010-03-12 10:47 ` Mel Gorman
2010-03-12 12:15 ` Christian Ehrhardt [this message]
2010-03-12 14:37 ` Andrew Morton
2010-03-15 12:29 ` Mel Gorman
2010-03-15 14:45 ` Christian Ehrhardt
2010-03-15 12:34 ` Christian Ehrhardt
2010-03-15 20:09 ` Andrew Morton
2010-03-16 10:11 ` Mel Gorman
2010-03-18 17:42 ` Mel Gorman
2010-03-22 23:50 ` Mel Gorman
2010-03-23 14:35 ` Christian Ehrhardt
2010-03-23 21:35 ` Corrado Zoccolo
2010-03-24 11:48 ` Mel Gorman
2010-03-24 12:56 ` Corrado Zoccolo
2010-03-23 22:29 ` Rik van Riel
2010-03-24 14:50 ` Mel Gorman
2010-04-19 12:22 ` Christian Ehrhardt
2010-04-19 21:44 ` Johannes Weiner
2010-04-20 7:20 ` Christian Ehrhardt
2010-04-20 8:54 ` Christian Ehrhardt
2010-04-20 15:32 ` Johannes Weiner
2010-04-20 17:22 ` Rik van Riel
2010-04-21 4:23 ` Christian Ehrhardt
2010-04-21 7:35 ` Christian Ehrhardt
2010-04-21 13:19 ` Rik van Riel
2010-04-22 6:21 ` Christian Ehrhardt
2010-04-26 10:59 ` Subject: [PATCH][RFC] mm: make working set portion that is protected tunable v2 Christian Ehrhardt
2010-04-26 11:59 ` KOSAKI Motohiro
2010-04-26 12:43 ` Christian Ehrhardt
2010-04-26 14:20 ` Rik van Riel
2010-04-27 14:00 ` Christian Ehrhardt
2010-04-21 9:03 ` [RFC PATCH 0/3] Avoid the use of congestion_wait under zone pressure Johannes Weiner
2010-04-21 13:20 ` Rik van Riel
2010-04-20 14:40 ` Rik van Riel
2010-03-24 2:38 ` Greg KH
2010-03-24 11:49 ` Mel Gorman
2010-03-24 13:13 ` Johannes Weiner
2010-03-12 9:09 ` Mel Gorman
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