writeback: account for time spent congestion_waited
authorMel Gorman <mel@csn.ul.ie>
Tue, 26 Oct 2010 21:21:41 +0000 (14:21 -0700)
committerLinus Torvalds <torvalds@linux-foundation.org>
Tue, 26 Oct 2010 23:52:07 +0000 (16:52 -0700)
commit52bb9198668968506f9d12bf35d7f5d3f094921e
tree6e1f79c46de902c4462054803eb13115673f8c8c
parente11da5b4fdf01d71d73c21cb92b00595b917d7fd
writeback: account for time spent congestion_waited

There is strong evidence to indicate a lot of time is being spent in
congestion_wait(), some of it unnecessarily.  This patch adds a tracepoint
for congestion_wait to record when congestion_wait() was called, how long
the timeout was for and how long it actually slept.

Signed-off-by: Mel Gorman <mel@csn.ul.ie>
Reviewed-by: Minchan Kim <minchan.kim@gmail.com>
Reviewed-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Wu Fengguang <fengguang.wu@intel.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Rik van Riel <riel@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
include/trace/events/writeback.h
mm/backing-dev.c