From: Jan Kara <jack@suse.cz>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Jan Kara <jack@suse.cz>,
linux-fsdevel@vger.kernel.org, linux-mm@kvack.org,
hch@infradead.org, akpm@linux-foundation.org,
wfg@mail.ustc.edu.cn
Subject: Re: [PATCH RFC] mm: Implement balance_dirty_pages() through waiting for flusher thread
Date: Mon, 21 Jun 2010 15:42:39 +0200 [thread overview]
Message-ID: <20100621134238.GE3828@quack.suse.cz> (raw)
In-Reply-To: <1276856497.27822.1699.camel@twins>
On Fri 18-06-10 12:21:37, Peter Zijlstra wrote:
> On Thu, 2010-06-17 at 20:04 +0200, Jan Kara wrote:
> > + if (bdi_stat(bdi, BDI_WRITTEN) >= bdi->wb_written_head)
> > + bdi_wakeup_writers(bdi);
>
> For the paranoid amongst us you could make wb_written_head s64 and write
> the above as:
>
> if (bdi_stat(bdi, BDI_WRITTEN) - bdi->wb_written_head > 0)
>
> Which, if you assume both are monotonic and wb_written_head is always
> within 2^63 of the actual bdi_stat() value, should give the same end
> result and deal with wrap-around.
>
> For when we manage to create a device that can write 2^64 pages in our
> uptime :-)
OK, the fix is simple enough so I've changed it, although I'm not
paranoic enough ;) (I actually did the math before writing that test).
Honza
--
Jan Kara <jack@suse.cz>
SUSE Labs, CR
next prev parent reply other threads:[~2010-06-21 13:43 UTC|newest]
Thread overview: 43+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-06-17 18:04 [PATCH RFC] mm: Implement balance_dirty_pages() through waiting for flusher thread Jan Kara
2010-06-18 6:09 ` Dave Chinner
2010-06-18 9:11 ` Peter Zijlstra
2010-06-18 23:29 ` Dave Chinner
2010-06-21 23:36 ` Jan Kara
2010-06-22 5:44 ` Dave Chinner
2010-06-22 6:14 ` Andrew Morton
2010-06-22 7:45 ` Peter Zijlstra
2010-06-22 8:24 ` Andrew Morton
2010-06-22 8:52 ` Peter Zijlstra
2010-06-22 10:09 ` Dave Chinner
2010-06-22 13:17 ` Jan Kara
2010-06-22 13:52 ` Wu Fengguang
2010-06-22 13:59 ` Peter Zijlstra
2010-06-22 14:00 ` Peter Zijlstra
2010-06-22 14:36 ` Wu Fengguang
2010-06-22 14:02 ` Jan Kara
2010-06-22 14:24 ` Wu Fengguang
2010-06-22 22:29 ` Dave Chinner
2010-06-23 13:15 ` Jan Kara
2010-06-23 23:06 ` Dave Chinner
2010-06-22 14:31 ` Christoph Hellwig
2010-06-22 14:38 ` Jan Kara
2010-06-22 22:45 ` Dave Chinner
2010-06-23 1:34 ` Wu Fengguang
2010-06-23 3:06 ` Dave Chinner
2010-06-23 3:22 ` Wu Fengguang
2010-06-23 6:03 ` Dave Chinner
2010-06-23 6:25 ` Wu Fengguang
2010-06-23 23:42 ` Dave Chinner
2010-06-22 14:41 ` Wu Fengguang
2010-06-22 11:19 ` Jan Kara
2010-06-18 10:21 ` Peter Zijlstra
2010-06-21 13:31 ` Jan Kara
2010-06-18 10:21 ` Peter Zijlstra
2010-06-21 14:02 ` Jan Kara
2010-06-21 14:10 ` Jan Kara
2010-06-21 14:12 ` Peter Zijlstra
2010-06-18 10:21 ` Peter Zijlstra
2010-06-21 13:42 ` Jan Kara [this message]
2010-06-22 4:07 ` Wu Fengguang
2010-06-22 13:27 ` Jan Kara
2010-06-22 13:33 ` Wu Fengguang
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