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authorMatt Johnston <matt@fugro-fsi.com.au>2012-12-21 10:15:34 +0800
committerBrian Behlendorf <behlendorf1@llnl.gov>2013-01-07 10:51:04 -0800
commit72f53c5694bfd57b56e79fc3b7c4390bce4072d2 (patch)
treef71ac31075af2f780e11b00276aa272ced5921ff /module
parent15f9d4e1c2b0ee26546e79d599df1b2adc2e5026 (diff)
Revert part of "Log I/Os longer than zio_delay_max (30s default)"
This reverts commit 9dcb97198338ba2d8764dd5604b278118612f74 which was originally introduced to debug occasional slow I/Os. These I/Os would complete eventually but were observed to take several 100 seconds. The root cause of this issue was the CFQ scheduler which can, under certain conditions, excessively delay an I/O from being issued to the device. This issue was mitigated somewhat by commit 84daaddedbfc9cf4bd1490d8a6f4b2967051e308 which ensures the I/O elevator gets changed even for DM style devices. This change isn't in any way harmful but it does conflict with a required change to properly account from I/O wait time. Because Linux does not export the io_schedule_timeout() function we must instead rely on io_schedule() via cv_wait_io(). The additional debugging information which was added to the delay event has been intentionally left in place. Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Diffstat (limited to 'module')
-rw-r--r--module/zfs/zio.c32
1 files changed, 10 insertions, 22 deletions
diff --git a/module/zfs/zio.c b/module/zfs/zio.c
index bcfc081d1..ece3329d0 100644
--- a/module/zfs/zio.c
+++ b/module/zfs/zio.c
@@ -1305,34 +1305,18 @@ __zio_execute(zio_t *zio)
int
zio_wait(zio_t *zio)
{
- uint64_t timeout;
int error;
ASSERT(zio->io_stage == ZIO_STAGE_OPEN);
ASSERT(zio->io_executor == NULL);
zio->io_waiter = curthread;
- timeout = ddi_get_lbolt() + (zio_delay_max / MILLISEC * hz);
__zio_execute(zio);
mutex_enter(&zio->io_lock);
- while (zio->io_executor != NULL) {
- /*
- * Wake up periodically to prevent the kernel from complaining
- * about a blocked task. However, check zio_delay_max to see
- * if the I/O has exceeded the timeout and post an ereport.
- */
- cv_timedwait_interruptible(&zio->io_cv, &zio->io_lock,
- ddi_get_lbolt() + hz);
-
- if (timeout && (ddi_get_lbolt() > timeout)) {
- zio->io_delay = zio_delay_max;
- zfs_ereport_post(FM_EREPORT_ZFS_DELAY,
- zio->io_spa, zio->io_vd, zio, 0, 0);
- timeout = 0;
- }
- }
+ while (zio->io_executor != NULL)
+ cv_wait(&zio->io_cv, &zio->io_lock);
mutex_exit(&zio->io_lock);
error = zio->io_error;
@@ -2905,11 +2889,15 @@ zio_done(zio_t *zio)
vdev_stat_update(zio, zio->io_size);
/*
- * When an I/O completes but was slow post an ereport.
+ * If this I/O is attached to a particular vdev is slow, exeeding
+ * 30 seconds to complete, post an error described the I/O delay.
+ * We ignore these errors if the device is currently unavailable.
*/
- if (zio->io_delay >= zio_delay_max)
- zfs_ereport_post(FM_EREPORT_ZFS_DELAY, zio->io_spa,
- zio->io_vd, zio, 0, 0);
+ if (zio->io_delay >= zio_delay_max) {
+ if (zio->io_vd != NULL && !vdev_is_dead(zio->io_vd))
+ zfs_ereport_post(FM_EREPORT_ZFS_DELAY, zio->io_spa,
+ zio->io_vd, zio, 0, 0);
+ }
if (zio->io_error) {
/*