redonkable/alistair23-linux
redonkable/alistair23-linux
1
0
Fork 0
Code Releases Activity

xfs: reduce the number of AIL push wakeups

Browse source 
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>
This commit is contained in:
Dave Chinner 2010-12-17 20:08:04 +11:00 committed by Dave Chinner
parent 0e57f6a36f
commit e677d0f954
1 changed files with 16 additions and 4 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

20
fs/xfs/linux-2.6/xfs_super.c
View file

@ -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();