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From: David Chinner <dgc@sgi.com>
To: Fengguang Wu <wfg@mail.ustc.edu.cn>
Cc: Andrew Morton <akpm@osdl.org>,
	linux-kernel@vger.kernel.org, David Chinner <dgc@sgi.com>,
	Ken Chen <kenchen@google.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Michael Rubin <mrubin@google.com>
Subject: Re: [PATCH 5/5] writeback: introduce writeback_control.more_io to indicate more io
Date: Wed, 3 Oct 2007 07:47:45 +1000	[thread overview]
Message-ID: <20071002214736.GJ995458@sgi.com> (raw)
In-Reply-To: <20071002090254.987182999@mail.ustc.edu.cn>

On Tue, Oct 02, 2007 at 04:41:48PM +0800, Fengguang Wu wrote:
>  		wbc.pages_skipped = 0;
> @@ -560,8 +561,9 @@ static void background_writeout(unsigned
>  		min_pages -= MAX_WRITEBACK_PAGES - wbc.nr_to_write;
>  		if (wbc.nr_to_write > 0 || wbc.pages_skipped > 0) {
>  			/* Wrote less than expected */
> -			congestion_wait(WRITE, HZ/10);
> -			if (!wbc.encountered_congestion)
> +			if (wbc.encountered_congestion || wbc.more_io)
> +				congestion_wait(WRITE, HZ/10);
> +			else
>  				break;
>  		}

Why do you call congestion_wait() if there is more I/O to issue?  If
we have a fast filesystem, this might cause the device queues to
fill, then drain on congestion_wait(), then fill again, etc. i.e. we
will have trouble keeping the queues full, right?

Cheers,

Dave.
-- 
Dave Chinner
Principal Engineer
SGI Australian Software Group

  parent reply	other threads:[~2007-10-02 21:48 UTC|newest]

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <20071002084143.110486039@mail.ustc.edu.cn>
2007-10-02  8:41 ` [PATCH 0/5] sluggish writeback fixes Fengguang Wu
2007-10-03 11:04   ` Martin Knoblauch
     [not found] ` <20071002090254.489150786@mail.ustc.edu.cn>
2007-10-02  8:41   ` [PATCH 1/5] revert check_dirty_inode_list.patch Fengguang Wu
     [not found] ` <20071002090254.596842343@mail.ustc.edu.cn>
2007-10-02  8:41   ` [PATCH 2/5] writeback: fix time ordering of the per superblock inode lists 8 Fengguang Wu
     [not found] ` <20071002090254.728493507@mail.ustc.edu.cn>
2007-10-02  8:41   ` [PATCH 3/5] writeback: fix ntfs with sb_has_dirty_inodes() Fengguang Wu
     [not found] ` <20071002090254.987182999@mail.ustc.edu.cn>
2007-10-02  8:41   ` [PATCH 5/5] writeback: introduce writeback_control.more_io to indicate more io Fengguang Wu
2007-10-02 21:47   ` David Chinner [this message]
     [not found]     ` <20071003013439.GA6501@mail.ustc.edu.cn>
2007-10-03  1:34       ` Fengguang Wu
2007-10-03  2:41       ` David Chinner
     [not found]         ` <20071004022133.GA6244@mail.ustc.edu.cn>
2007-10-04  2:21           ` Fengguang Wu
2007-10-04  5:03           ` David Chinner
     [not found]             ` <20071005033652.GA6448@mail.ustc.edu.cn>
2007-10-05  3:36               ` Fengguang Wu
2007-10-05  7:41               ` David Chinner
     [not found]                 ` <20071005115508.GA9998@mail.ustc.edu.cn>
2007-10-05 11:55                   ` Fengguang Wu
     [not found] ` <20071002090254.873023041@mail.ustc.edu.cn>
2007-10-02  8:41   ` [PATCH 4/5] writeback: remove pages_skipped accounting in __block_write_full_page() Fengguang Wu
2007-10-04 21:26     ` Andrew Morton
2007-10-02 21:55   ` David Chinner
     [not found]     ` <20071003014333.GB6501@mail.ustc.edu.cn>
2007-10-03  1:43       ` Fengguang Wu
2007-10-03  2:22       ` David Chinner

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