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From: Dave Chinner <david@fromorbit.com>
To: xfs@oss.sgi.com
Subject: [PATCH 5/9] xfs: reduce the number of AIL push wakeups
Date: Mon, 13 Dec 2010 15:32:19 +1100	[thread overview]
Message-ID: <1292214743-18073-6-git-send-email-david@fromorbit.com> (raw)
In-Reply-To: <1292214743-18073-1-git-send-email-david@fromorbit.com>

From: Dave Chinner <dchinner@redhat.com>

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 <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
---
 fs/xfs/linux-2.6/xfs_super.c |   20 ++++++++++++++++----
 1 files 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 abcda07..b49ad02 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_UNINTERRUPTIBLE);
+		schedule_timeout(tout ?
+				 msecs_to_jiffies(tout) : MAX_SCHEDULE_TIMEOUT);
 
 		/* swsusp */
 		try_to_freeze();
-- 
1.7.2.3

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  parent reply	other threads:[~2010-12-13  4:32 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-12-13  4:32 xfs: AIL lock contention reduction V3 Dave Chinner
2010-12-13  4:32 ` [PATCH 1/9] xfs: fix EFI transaction cancellation Dave Chinner
2010-12-17 11:18   ` Christoph Hellwig
2010-12-13  4:32 ` [PATCH 2/9] xfs: Pull EFI/EFD handling out from under the AIL lock Dave Chinner
2010-12-17 11:22   ` Christoph Hellwig
2010-12-20  1:00     ` Dave Chinner
2010-12-13  4:32 ` [PATCH 3/9] xfs: clean up xfs_ail_delete() Dave Chinner
2010-12-13  4:32 ` [PATCH 4/9] xfs: bulk AIL insertion during transaction commit Dave Chinner
2010-12-17 11:25   ` Christoph Hellwig
2010-12-13  4:32 ` Dave Chinner [this message]
2010-12-16 15:38   ` [PATCH 5/9] xfs: reduce the number of AIL push wakeups Christoph Hellwig
2010-12-16 21:50     ` Dave Chinner
2010-12-17  0:23       ` Christoph Hellwig
2010-12-13  4:32 ` [PATCH 6/9] xfs: consume iodone callback items on buffers as they are processed Dave Chinner
2010-12-13  4:32 ` [PATCH 7/9] xfs: remove all the inodes on a buffer from the AIL in bulk Dave Chinner
2010-12-17 11:25   ` Christoph Hellwig
2010-12-13  4:32 ` [PATCH 9/9] xfs: use AIL bulk delete function to implement single delete Dave Chinner
2010-12-17 14:16   ` Christoph Hellwig

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