From: Andrew Morton <akpm@linux-foundation.org>
To: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Wu Fengguang <fengguang.wu@intel.com>,
stable@kernel.org, Rik van Riel <riel@redhat.com>,
Mel Gorman <mel@csn.ul.ie>, Christoph Hellwig <hch@infradead.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"linux-fsdevel@vger.kernel.org" <linux-fsdevel@vger.kernel.org>,
"linux-mm@kvack.org" <linux-mm@kvack.org>,
Dave Chinner <david@fromorbit.com>,
Chris Mason <chris.mason@oracle.com>,
Nick Piggin <npiggin@suse.de>,
Johannes Weiner <hannes@cmpxchg.org>,
KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>,
Andrea Arcangeli <aarcange@redhat.com>,
Minchan Kim <minchan.kim@gmail.com>, Andreas Mohr <andi@lisas.de>,
Bill Davidsen <davidsen@tmr.com>,
Ben Gamari <bgamari.foss@gmail.com>
Subject: Re: Why PAGEOUT_IO_SYNC stalls for a long time
Date: Wed, 28 Jul 2010 10:30:56 -0700 [thread overview]
Message-ID: <20100728103056.c5511c78.akpm@linux-foundation.org> (raw)
In-Reply-To: <20100728191322.4A85.A69D9226@jp.fujitsu.com>
On Wed, 28 Jul 2010 20:40:21 +0900 (JST) KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> wrote:
> 3. pageout() is intended anynchronous api. but doesn't works so.
>
> pageout() call ->writepage with wbc->nonblocking=1. because if the system have
> default vm.dirty_ratio (i.e. 20), we have 80% clean memory. so, getting stuck
> on one page is stupid, we should scan much pages as soon as possible.
>
> HOWEVER, block layer ignore this argument. if slow usb memory device connect
> to the system, ->writepage() will sleep long time. because submit_bio() call
> get_request_wait() unconditionally and it doesn't have any PF_MEMALLOC task
> bonus.
The idea is that vmscan doesn't call ->writepage if the underlying
queue is congested. may_write_to_queue()->bdi_queue_congested() should
return false and we skip the write.
If that logic is broken then that would explain a few things...
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next prev parent reply other threads:[~2010-07-28 17:30 UTC|newest]
Thread overview: 35+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-07-28 7:17 [PATCH] vmscan: raise the bar to PAGEOUT_IO_SYNC stalls Wu Fengguang
2010-07-28 7:49 ` Minchan Kim
2010-07-28 8:46 ` [PATCH] vmscan: remove wait_on_page_writeback() from pageout() Wu Fengguang
2010-07-28 9:10 ` Mel Gorman
2010-07-28 9:30 ` Wu Fengguang
2010-07-28 9:45 ` Mel Gorman
2010-07-28 9:43 ` KOSAKI Motohiro
2010-07-28 9:50 ` Mel Gorman
2010-07-28 9:59 ` KOSAKI Motohiro
2010-08-01 5:27 ` Wu Fengguang
2010-08-01 5:49 ` Wu Fengguang
2010-08-01 8:32 ` KOSAKI Motohiro
2010-08-01 8:35 ` Wu Fengguang
2010-08-01 8:40 ` KOSAKI Motohiro
2010-08-01 5:17 ` Wu Fengguang
2010-07-28 16:29 ` Minchan Kim
2010-07-28 11:40 ` Why PAGEOUT_IO_SYNC stalls for a long time KOSAKI Motohiro
2010-07-28 13:10 ` Mel Gorman
2010-07-29 10:34 ` KOSAKI Motohiro
2010-07-29 14:24 ` Mel Gorman
2010-07-30 4:54 ` KOSAKI Motohiro
2010-07-30 10:30 ` Mel Gorman
2010-08-01 8:47 ` KOSAKI Motohiro
2010-08-04 11:10 ` Mel Gorman
2010-08-05 6:20 ` KOSAKI Motohiro
2010-08-05 8:09 ` Andreas Mohr
2010-07-28 17:30 ` Andrew Morton [this message]
2010-07-29 1:01 ` KOSAKI Motohiro
2010-07-30 13:17 ` [PATCH] vmscan: raise the bar to PAGEOUT_IO_SYNC stalls Andrea Arcangeli
2010-07-30 13:31 ` Mel Gorman
2010-07-31 16:13 ` Wu Fengguang
2010-07-31 17:33 ` Christoph Hellwig
2010-07-31 17:55 ` Pekka Enberg
2010-07-31 17:59 ` Christoph Hellwig
2010-07-31 18:09 ` Pekka Enberg
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