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Fix for "Reduce latency effects of non-interactive I/O" 

It was found that setting min_active tunables for non-interactive I/Os
makes them stuck.  It is caused by zfs_vdev_nia_delay, that can never
be reached if we never issue any I/Os due to min_active set to zero.

Fix this by issuing at least one non-interactive I/O at a time when
there are no interactive I/Os.  When there are interactive I/Os, zero
min_active allows to completely block any non-interactive I/O.  It may
min_active starvation in some scenarios, but who we are to deny foot
shooting?

Reviewed-by: George Melikov <mail@gmelikov.ru>
Reviewed-by: Ryan Moeller <ryan@iXsystems.com>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Alexander Motin <mav@FreeBSD.org>
Closes #11261
This commit is contained in:
Alexander Motin 2020-12-03 13:02:39 -05:00 committed by GitHub
parent 9109b89cd7
commit dcf7044522
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1 changed files with 4 additions and 4 deletions
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8
module/zfs/vdev_queue.c
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@ -380,21 +380,21 @@ vdev_queue_class_max_active(spa_t *spa, vdev_queue_t *vq, zio_priority_t p)
return (MIN(vq->vq_nia_credit,
zfs_vdev_scrub_min_active));
} else if (vq->vq_nia_credit < zfs_vdev_nia_delay)
return (zfs_vdev_scrub_min_active);
return (MAX(1, zfs_vdev_scrub_min_active));
return (zfs_vdev_scrub_max_active);
case ZIO_PRIORITY_REMOVAL:
if (vq->vq_ia_active > 0) {
return (MIN(vq->vq_nia_credit,
zfs_vdev_removal_min_active));
} else if (vq->vq_nia_credit < zfs_vdev_nia_delay)
return (zfs_vdev_removal_min_active);
return (MAX(1, zfs_vdev_removal_min_active));
return (zfs_vdev_removal_max_active);
case ZIO_PRIORITY_INITIALIZING:
if (vq->vq_ia_active > 0) {
return (MIN(vq->vq_nia_credit,
zfs_vdev_initializing_min_active));
} else if (vq->vq_nia_credit < zfs_vdev_nia_delay)
return (zfs_vdev_initializing_min_active);
return (MAX(1, zfs_vdev_initializing_min_active));
return (zfs_vdev_initializing_max_active);
case ZIO_PRIORITY_TRIM:
return (zfs_vdev_trim_max_active);
@ -403,7 +403,7 @@ vdev_queue_class_max_active(spa_t *spa, vdev_queue_t *vq, zio_priority_t p)
return (MIN(vq->vq_nia_credit,
zfs_vdev_rebuild_min_active));
} else if (vq->vq_nia_credit < zfs_vdev_nia_delay)
return (zfs_vdev_rebuild_min_active);
return (MAX(1, zfs_vdev_rebuild_min_active));
return (zfs_vdev_rebuild_max_active);
default:
panic("invalid priority %u", p);