From: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
To: Tao Ma <tm@tao.ma>
Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org,
David Rientjes <rientjes@google.com>,
Minchan Kim <minchan.kim@gmail.com>, Mel Gorman <mel@csn.ul.ie>,
Johannes Weiner <jweiner@redhat.com>,
Andrew Morton <akpm@linux-foundation.org>
Subject: Re: [PATCH] mm: do not drain pagevecs for mlock
Date: Fri, 30 Dec 2011 03:11:49 -0500 [thread overview]
Message-ID: <CAHGf_=qOGy3MQgiFyfeG82+gbDXTBT5KQjgR7JqMfQ7e7RSGpA@mail.gmail.com> (raw)
In-Reply-To: <1325226961-4271-1-git-send-email-tm@tao.ma>
2011/12/30 Tao Ma <tm@tao.ma>:
> In our test of mlock, we have found some severe performance regression
> in it. Some more investigations show that mlocked is blocked heavily
> by lur_add_drain_all which calls schedule_on_each_cpu and flush the work
> queue which is very slower if we have several cpus.
>
> So we have tried 2 ways to solve it:
> 1. Add a per cpu counter for all the pagevecs so that we don't schedule
> and flush the lru_drain work if the cpu doesn't have any pagevecs(I
> have finished the codes already).
> 2. Remove the lru_add_drain_all.
>
> The first one has some problems since in our product system, all the cpus
> are busy, so I guess there is very little chance for a cpu to have 0 pagevecs
> except that you run several consecutive mlocks.
>
> From the commit log which added this function(8891d6da), it seems that we
> don't have to call it. So the 2nd one seems to be both easy and workable and
> comes this patch.
Could you please show us your system environment and benchmark programs?
Usually lru_drain_** is very fast than mlock() body because it makes
plenty memset(page).
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next prev parent reply other threads:[~2011-12-30 8:12 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-12-30 6:36 Tao Ma
2011-12-30 8:11 ` KOSAKI Motohiro [this message]
2011-12-30 8:48 ` Tao Ma
2011-12-30 9:31 ` KOSAKI Motohiro
2011-12-30 9:45 ` Tao Ma
2011-12-30 10:07 ` KOSAKI Motohiro
2012-01-01 7:30 ` [PATCH 1/2] mm,mlock: drain pagevecs asynchronously kosaki.motohiro
2012-01-04 1:17 ` Minchan Kim
2012-01-04 2:38 ` KOSAKI Motohiro
2012-01-10 8:53 ` Tao Ma
2012-01-04 2:56 ` Hugh Dickins
2012-01-04 22:05 ` Andrew Morton
2012-01-04 23:33 ` KOSAKI Motohiro
2012-01-05 0:19 ` Hugh Dickins
2012-01-01 7:30 ` [PATCH 2/2] sysvshm: SHM_LOCK use lru_add_drain_all_async() kosaki.motohiro
2012-01-04 1:51 ` Hugh Dickins
2012-01-04 2:19 ` KOSAKI Motohiro
2012-01-04 5:17 ` Hugh Dickins
2012-01-04 8:34 ` KOSAKI Motohiro
2012-01-06 6:13 ` [PATCH] mm: do not drain pagevecs for mlock Tao Ma
2012-01-06 6:18 ` KOSAKI Motohiro
2012-01-06 6:30 ` Tao Ma
2012-01-06 6:33 ` KOSAKI Motohiro
2012-01-06 6:46 ` Tao Ma
2012-01-09 23:58 ` KOSAKI Motohiro
2012-01-10 2:08 ` Tao Ma
2012-01-09 7:25 ` Tao Ma
2011-12-30 10:14 ` KOSAKI Motohiro
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