From mboxrd@z Thu Jan  1 00:00:00 1970
From: Wu Fengguang <fengguang.wu@intel.com>
Subject: [PATCH 0/3] bdi write bandwidth estimation
Date: Sun, 12 Jun 2011 23:18:21 +0800
Message-ID: <20110612151821.601514494@intel.com>
Cc: Jan Kara <jack@suse.cz>
To: <linux-fsdevel@vger.kernel.org>
Return-path: <linux-kernel-owner@vger.kernel.org>
cc: Dave Chinner <david@fromorbit.com>
cc: Christoph Hellwig <hch@infradead.org>
cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Wu Fengguang <fengguang.wu@intel.com>,
	LKML <linux-kernel@vger.kernel.org>
Sender: linux-kernel-owner@vger.kernel.org
List-Id: linux-fsdevel.vger.kernel.org


Do bdi write bandwidth estimation in the flusher thread at 200ms intervals,
and in case the flusher is blocked syncing large files, the throttled dirtier
tasks will back it up.

To get an idea of the adaption speed and fluctuation range, here are
some real examples (check the red dots and the yellow line):

http://www.kernel.org/pub/linux/kernel/people/wfg/writeback/dirty-throttling-v8/3G/xfs-1dd-4k-8p-2948M-20:10-3.0.0-rc2-next-20110610+-2011-06-12.21:51/balance_dirty_pages-bandwidth.png
http://www.kernel.org/pub/linux/kernel/people/wfg/writeback/dirty-throttling-v8/3G/ext3-1dd-4k-8p-2948M-20:10-3.0.0-rc2-next-20110610+-2011-06-12.22:02/balance_dirty_pages-bandwidth.png
http://www.kernel.org/pub/linux/kernel/people/wfg/writeback/dirty-throttling-v8/3G/ext4-1dd-4k-8p-2948M-20:10-3.0.0-rc2-next-20110610+-2011-06-12.21:57/balance_dirty_pages-bandwidth.png
http://www.kernel.org/pub/linux/kernel/people/wfg/writeback/dirty-throttling-v8/3G/btrfs-1dd-4k-8p-2948M-20:10-3.0.0-rc2-next-20110610+-2011-06-12.22:07/balance_dirty_pages-bandwidth.png

The old version outputs, for your reference:

http://www.kernel.org/pub/linux/kernel/people/wfg/writeback/dirty-throttling-v6/4G-60%25/ext3-1dd-1M-8p-3911M-60%25-2.6.38-rc5-dt6+-2011-02-22-11-51/balance_dirty_pages-bandwidth.png
http://www.kernel.org/pub/linux/kernel/people/wfg/writeback/dirty-throttling-v6/4G-60%25/xfs-1dd-1M-8p-3911M-60%25-2.6.38-rc5-dt6+-2011-02-22-11-10/balance_dirty_pages-bandwidth.png
http://www.kernel.org/pub/linux/kernel/people/wfg/writeback/dirty-throttling-v6/NFS/nfs-1dd-1M-8p-2945M-20%25-2.6.38-rc6-dt6+-2011-02-22-21-09/balance_dirty_pages-bandwidth.png

This is merely the estimation part. The in-kernel users of the estimated
bandwidth will follow in the coming series.

Thanks,
Fengguang