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authorDave Chinner <dchinner@redhat.com>2010-12-17 20:08:04 +1100
committerDave Chinner <david@fromorbit.com>2010-12-17 20:08:04 +1100
commite677d0f9548e2245ee3c2977661ca8ca165af188 (patch)
tree28e20df79bcd8c5aa7458c85fd58cf7f5feb4e69 /fs/xfs
parent0e57f6a36f9be03e5abb755f524ee91c4aebe854 (diff)
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 <dchinner@redhat.com> Reviewed-by: Christoph Hellwig <hch@lst.de>
Diffstat (limited to 'fs/xfs')
-rw-r--r--fs/xfs/linux-2.6/xfs_super.c20
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 c45b3233d486..c51faaa5e291 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();