From 0c081dba0add2fd09c80c88a4384618003d7e3ec Mon Sep 17 00:00:00 2001 From: Alexander Motin Date: Tue, 1 Dec 2020 12:48:34 -0500 Subject: [PATCH] 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? Signed-off-by: Alexander Motin --- module/zfs/vdev_queue.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/module/zfs/vdev_queue.c b/module/zfs/vdev_queue.c index 5fb1d84b23c0..6f3c4208aca2 100644 --- a/module/zfs/vdev_queue.c +++ b/module/zfs/vdev_queue.c @@ -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);