Messages in this thread | | | Subject | Re: [PATCH 02/10] writeback: balance_dirty_pages() shall write more than dirtied pages | From | Peter Zijlstra <> | Date | Thu, 24 Sep 2009 17:03:34 +0200 |
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On Thu, 2009-09-24 at 16:40 +0200, Jens Axboe wrote: > From: Wu Fengguang <fengguang.wu@intel.com> > > Some filesystem may choose to write much more than ratelimit_pages > before calling balance_dirty_pages_ratelimited_nr(). So it is safer to > determine number to write based on real number of dirtied pages. > > Otherwise it is possible that > loop { > btrfs_file_write(): dirty 1024 pages > balance_dirty_pages(): write up to 48 pages (= ratelimit_pages * 1.5) > } > in which the writeback rate cannot keep up with dirty rate, and the > dirty pages go all the way beyond dirty_thresh. > > The increased write_chunk may make the dirtier more bumpy. > So filesystems shall be take care not to dirty too much at > a time (eg. > 4MB) without checking the ratelimit. > > Signed-off-by: Wu Fengguang <fengguang.wu@intel.com> > Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
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