Commit 82e230a0 authored by Wu Fengguang's avatar Wu Fengguang
Browse files

writeback: set max_pause to lowest value on zero bdi_dirty

Some trace shows lots of bdi_dirty=0 lines where it's actually some
small value if w/o the accounting errors in the per-cpu bdi stats.

In this case the max pause time should really be set to the smallest
(non-zero) value to avoid IO queue underrun and improve throughput.
Signed-off-by: default avatarWu Fengguang <>
parent c5c6343c
......@@ -989,8 +989,7 @@ static unsigned long bdi_max_pause(struct backing_dev_info *bdi,
* 8 serves as the safety ratio.
if (bdi_dirty)
t = min(t, bdi_dirty * HZ / (8 * bw + 1));
t = min(t, bdi_dirty * HZ / (8 * bw + 1));
* The pause time will be settled within range (max_pause/4, max_pause).
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