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 -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
