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From: Wu Fengguang <fengguang.wu@intel.com>
To: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Neil Brown <neilb@suse.de>, linux-mm <linux-mm@kvack.org>,
	LKML <linux-kernel@vger.kernel.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	Theodore Ts'o <tytso@mit.edu>, Dave Chinner <david@fromorbit.com>,
	Jan Kara <jack@suse.cz>, Peter Zijlstra <a.p.zijlstra@chello.nl>,
	Mel Gorman <mel@csn.ul.ie>, Rik van Riel <riel@redhat.com>,
	Chris Mason <chris.mason@oracle.com>,
	Christoph Hellwig <hch@lst.de>,
	"Li, Shaohua" <shaohua.li@intel.com>
Subject: Re: [PATCH 05/17] writeback: quit throttling when signal pending
Date: Tue, 14 Sep 2010 16:33:38 +0800	[thread overview]
Message-ID: <20100914083338.GA20295@localhost> (raw)
In-Reply-To: <20100914172028.C9B2.A69D9226@jp.fujitsu.com>

On Tue, Sep 14, 2010 at 04:23:56PM +0800, KOSAKI Motohiro wrote:
> > Subject: writeback: quit throttling when fatal signal pending
> > From: Wu Fengguang <fengguang.wu@intel.com>
> > Date: Wed Sep 08 17:40:22 CST 2010
> > 
> > This allows quick response to Ctrl-C etc. for impatient users.
> > 
> > It mainly helps the rare bdi/global dirty exceeded cases.
> > In the normal case of not exceeded, it will quit the loop anyway. 
> > 
> > CC: Neil Brown <neilb@suse.de>
> > Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
> > ---
> >  mm/page-writeback.c |    3 +++
> >  1 file changed, 3 insertions(+)
> > 
> > --- linux-next.orig/mm/page-writeback.c	2010-09-12 13:25:23.000000000 +0800
> > +++ linux-next/mm/page-writeback.c	2010-09-13 11:39:33.000000000 +0800
> > @@ -552,6 +552,9 @@ static void balance_dirty_pages(struct a
> >  		__set_current_state(TASK_INTERRUPTIBLE);
> >  		io_schedule_timeout(pause);
> >  
> > +		if (fatal_signal_pending(current))
> > +			break;
> > +
> >  check_exceeded:
> >  		/*
> >  		 * The bdi thresh is somehow "soft" limit derived from the
> 
> I think we need to change callers (e.g. generic_perform_write) too.
> Otherwise, plenty write + SIGKILL combination easily exceed dirty limit.
> It mean we can see strange OOM.

If it's dangerous, we can do without this patch.  The users can still
get quick response in normal case after all.

However, I suspect the process is guaranteed to exit on
fatal_signal_pending, so it won't dirty more pages :)

Thanks,
Fengguang

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  reply	other threads:[~2010-09-14  8:33 UTC|newest]

Thread overview: 49+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-09-12 15:49 [PATCH 00/17] [RFC] soft and dynamic dirty throttling limits Wu Fengguang
2010-09-12 15:49 ` [PATCH 01/17] writeback: remove the internal 5% low bound on dirty_ratio Wu Fengguang
2010-09-13  9:23   ` Johannes Weiner
2010-09-13  9:51   ` Mel Gorman
2010-09-13  9:57     ` Wu Fengguang
2010-09-13 10:10       ` Mel Gorman
2010-09-12 15:49 ` [PATCH 02/17] writeback: IO-less balance_dirty_pages() Wu Fengguang
2010-09-13  8:45   ` Dave Chinner
2010-09-13 11:38     ` Wu Fengguang
2010-09-12 15:49 ` [PATCH 03/17] writeback: per-task rate limit to balance_dirty_pages() Wu Fengguang
2010-09-12 15:49 ` [PATCH 04/17] writeback: quit throttling when bdi dirty/writeback pages go down Wu Fengguang
2010-09-12 15:49 ` [PATCH 05/17] writeback: quit throttling when signal pending Wu Fengguang
2010-09-12 20:46   ` Neil Brown
2010-09-13  1:55     ` Wu Fengguang
2010-09-13  3:21       ` Neil Brown
2010-09-13  3:48         ` Wu Fengguang
2010-09-14  8:23           ` KOSAKI Motohiro
2010-09-14  8:33             ` Wu Fengguang [this message]
2010-09-14  8:44               ` KOSAKI Motohiro
2010-09-14  9:17                 ` Wu Fengguang
2010-09-14  9:25                   ` KOSAKI Motohiro
2010-09-12 15:49 ` [PATCH 06/17] writeback: move task dirty fraction to balance_dirty_pages() Wu Fengguang
2010-09-12 15:49 ` [PATCH 07/17] writeback: add trace event for balance_dirty_pages() Wu Fengguang
2010-09-12 15:49 ` [PATCH 08/17] writeback: account per-bdi accumulated written pages Wu Fengguang
2010-09-12 15:59   ` Wu Fengguang
2010-09-14  8:32   ` KOSAKI Motohiro
2010-09-12 15:49 ` [PATCH 09/17] writeback: bdi write bandwidth estimation Wu Fengguang
2010-09-12 15:49 ` [PATCH 10/17] writeback: show bdi write bandwidth in debugfs Wu Fengguang
2010-09-12 15:49 ` [PATCH 11/17] writeback: make nr_to_write a per-file limit Wu Fengguang
2010-09-12 15:49 ` [PATCH 12/17] writeback: scale IO chunk size up to device bandwidth Wu Fengguang
2010-09-12 15:49 ` [PATCH 13/17] writeback: reduce per-bdi dirty threshold ramp up time Wu Fengguang
2010-09-12 16:15   ` Wu Fengguang
2010-09-12 15:49 ` [PATCH 14/17] vmscan: add scan_control.priority Wu Fengguang
2010-09-12 15:50 ` [PATCH 15/17] mm: lower soft dirty limits on memory pressure Wu Fengguang
2010-09-13  9:40   ` Wu Fengguang
2010-09-12 15:50 ` [PATCH 16/17] mm: create /vm/dirty_pressure in debugfs Wu Fengguang
2010-09-12 15:50 ` [PATCH 17/17] writeback: consolidate balance_dirty_pages() variable names Wu Fengguang
2010-10-12 14:17 ` [PATCH 00/17] [RFC] soft and dynamic dirty throttling limits Christoph Hellwig
2010-10-13  3:07   ` Dave Chinner
2010-10-13  3:23     ` Wu Fengguang
2010-10-13  8:26     ` Wu Fengguang
2010-10-13  9:26       ` Dave Chinner
2010-11-01  6:24         ` Dave Chinner
2010-11-04  3:41           ` Wu Fengguang
2010-11-04 12:48             ` Dave Chinner
2010-11-04 13:12             ` Christoph Hellwig
2010-11-05 14:56               ` Wu Fengguang
2010-11-06 10:42                 ` Dave Chinner
2010-10-14 13:12   ` Wu Fengguang

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