Message-ID: <4C5AD348.3050404@redhat.com>
Date: Thu, 05 Aug 2010 11:05:44 -0400
From: Rik van Riel <riel@redhat.com>
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To: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
CC: LKML <linux-kernel@vger.kernel.org>, linux-mm <linux-mm@kvack.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        Johannes Weiner <hannes@cmpxchg.org>, Mel Gorman <mel@csn.ul.ie>,
        Wu Fengguang <fengguang.wu@intel.com>,
        Minchan Kim <minchan.kim@gmail.com>
Subject: Re: [PATCH 2/7] vmscan: synchronous lumpy reclaim don't call congestion_wait()
References: <20100805150624.31B7.A69D9226@jp.fujitsu.com> <20100805151229.31BD.A69D9226@jp.fujitsu.com>
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On 08/05/2010 02:13 AM, KOSAKI Motohiro wrote:
> congestion_wait() mean "waiting quueue congestion is cleared".
> That said, if the system have plenty dirty pages and flusher thread push
> new request to IO queue conteniously, IO queue are not cleared
> congestion status for long time. thus, congestion_wait(HZ/10) become
> almostly equivalent schedule_timeout(HZ/10).
>
> However, synchronous lumpy reclaim donesn't need this
> congestion_wait() at all. shrink_page_list(PAGEOUT_IO_SYNC) are
> using wait_on_page_writeback() and it provide sufficient waiting.
>
> Signed-off-by: KOSAKI Motohiro<kosaki.motohiro@jp.fujitsu.com>

Acked-by: Rik van Riel <riel@redhat.com>

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