From e677d0f9548e2245ee3c2977661ca8ca165af188 Mon Sep 17 00:00:00 2001 From: Dave Chinner Date: Fri, 17 Dec 2010 20:08:04 +1100 Subject: xfs: reduce the number of AIL push wakeups The xfaild often tries to rest to wait for congestion to pass of for IO to complete, but is regularly woken in tail-pushing situations. In severe cases, the xfsaild is getting woken tens of thousands of times a second. Reduce the number needless wakeups by only waking the xfsaild if the new target is larger than the old one. Further make short sleeps uninterruptible as they occur when the xfsaild has decided it needs to back off to allow some IO to complete and being woken early is counter-productive. Signed-off-by: Dave Chinner Reviewed-by: Christoph Hellwig --- fs/xfs/linux-2.6/xfs_super.c | 20 ++++++++++++++++---- 1 file changed, 16 insertions(+), 4 deletions(-) diff --git a/fs/xfs/linux-2.6/xfs_super.c b/fs/xfs/linux-2.6/xfs_super.c index c45b323..c51faaa 100644 --- a/fs/xfs/linux-2.6/xfs_super.c +++ b/fs/xfs/linux-2.6/xfs_super.c @@ -834,8 +834,11 @@ xfsaild_wakeup( struct xfs_ail *ailp, xfs_lsn_t threshold_lsn) { - ailp->xa_target = threshold_lsn; - wake_up_process(ailp->xa_task); + /* only ever move the target forwards */ + if (XFS_LSN_CMP(threshold_lsn, ailp->xa_target) > 0) { + ailp->xa_target = threshold_lsn; + wake_up_process(ailp->xa_task); + } } STATIC int @@ -847,8 +850,17 @@ xfsaild( long tout = 0; /* milliseconds */ while (!kthread_should_stop()) { - schedule_timeout_interruptible(tout ? - msecs_to_jiffies(tout) : MAX_SCHEDULE_TIMEOUT); + /* + * for short sleeps indicating congestion, don't allow us to + * get woken early. Otherwise all we do is bang on the AIL lock + * without making progress. + */ + if (tout && tout <= 20) + __set_current_state(TASK_KILLABLE); + else + __set_current_state(TASK_INTERRUPTIBLE); + schedule_timeout(tout ? + msecs_to_jiffies(tout) : MAX_SCHEDULE_TIMEOUT); /* swsusp */ try_to_freeze(); -- cgit v1.1