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From: Peter Zijlstra <peterz@infradead.org>
To: Jan Kara <jack@suse.cz>
Cc: 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: Fri, 18 Jun 2010 12:21:37 +0200	[thread overview]
Message-ID: <1276856497.27822.1699.camel@twins> (raw)
In-Reply-To: <1276797878-28893-1-git-send-email-jack@suse.cz>

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 :-)

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  parent reply	other threads:[~2010-06-18 10:21 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 [this message]
2010-06-21 13:42   ` Jan Kara
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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