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author | Wu Fengguang <fengguang.wu@intel.com> | 2009-09-23 21:56:00 +0800 |
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committer | Jens Axboe <jens.axboe@oracle.com> | 2009-09-25 18:08:24 +0200 |
commit | 3a2e9a5a2afc1a2d2c548b8987f133235cebe933 (patch) | |
tree | cb05d2873b2701ded758a7087de5af2932a97736 /fs/fs-writeback.c | |
parent | a5989bdc981ec85e0734ac22519cc0b780813d7b (diff) | |
download | linux-3a2e9a5a2afc1a2d2c548b8987f133235cebe933.tar.bz2 |
writeback: balance_dirty_pages() shall write more than dirtied pages
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>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
Diffstat (limited to 'fs/fs-writeback.c')
0 files changed, 0 insertions, 0 deletions