From: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
To: Shaohua Li <shaohua.li@intel.com>
Cc: kosaki.motohiro@jp.fujitsu.com,
"linux-mm@kvack.org" <linux-mm@kvack.org>,
Andrew Morton <akpm@linux-foundation.org>,
Mel Gorman <mel@csn.ul.ie>
Subject: Re: [RFC]pagealloc: compensate a task for direct page reclaim
Date: Fri, 17 Sep 2010 14:52:39 +0900 (JST) [thread overview]
Message-ID: <20100917145224.3BDB.A69D9226@jp.fujitsu.com> (raw)
In-Reply-To: <1284636396.1726.5.camel@shli-laptop>
> A task enters into direct page reclaim, free some memory. But sometimes
> the task can't get a free page after direct page reclaim because
> other tasks take them (this is quite common in a multi-task workload
> in my test). This behavior will bring extra latency to the task and is
> unfair. Since the task already gets penalty, we'd better give it a compensation.
> If a task frees some pages from direct page reclaim, we cache one freed page,
> and the task will get it soon. We only consider order 0 allocation, because
> it's hard to cache order > 0 page.
>
> Below is a trace output when a task frees some pages in try_to_free_pages(), but
> get_page_from_freelist() can't get a page in direct page reclaim.
>
> <...>-809 [004] 730.218991: __alloc_pages_nodemask: progress 147, order 0, pid 809, comm mmap_test
> <...>-806 [001] 730.237969: __alloc_pages_nodemask: progress 147, order 0, pid 806, comm mmap_test
> <...>-810 [005] 730.237971: __alloc_pages_nodemask: progress 147, order 0, pid 810, comm mmap_test
> <...>-809 [004] 730.237972: __alloc_pages_nodemask: progress 147, order 0, pid 809, comm mmap_test
> <...>-811 [006] 730.241409: __alloc_pages_nodemask: progress 147, order 0, pid 811, comm mmap_test
> <...>-809 [004] 730.241412: __alloc_pages_nodemask: progress 147, order 0, pid 809, comm mmap_test
> <...>-812 [007] 730.241435: __alloc_pages_nodemask: progress 147, order 0, pid 812, comm mmap_test
> <...>-809 [004] 730.245036: __alloc_pages_nodemask: progress 147, order 0, pid 809, comm mmap_test
> <...>-809 [004] 730.260360: __alloc_pages_nodemask: progress 147, order 0, pid 809, comm mmap_test
> <...>-805 [000] 730.260362: __alloc_pages_nodemask: progress 147, order 0, pid 805, comm mmap_test
> <...>-811 [006] 730.263877: __alloc_pages_nodemask: progress 147, order 0, pid 811, comm mmap_test
As far as I remembered, two years ago, similar patches was posted. but
minchan found it makes performance regression when kernbench run.
http://archives.free.net.ph/message/20080905.101958.0f84e87d.ja.html
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prev parent reply other threads:[~2010-09-17 5:52 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-09-16 11:26 [RFC]pagealloc: compensate a task for direct page reclaim Shaohua Li
2010-09-16 15:00 ` Minchan Kim
2010-09-17 2:34 ` Shaohua Li
2010-09-17 4:47 ` Minchan Kim
2010-09-20 8:50 ` Mel Gorman
2010-09-17 5:52 ` KOSAKI Motohiro [this message]
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