Commit 82e230a0 authored Dec 02, 2011 by Wu Fengguang

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: Wu Fengguang <fengguang.wu@intel.com>

parent c5c6343c

mm/page-writeback.c

+1 −2

Original line number	Diff line number	Diff line
		@@ -989,7 +989,6 @@ 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));

		/*