Add vdev property to disable vdev scheduler

Added vdev property to disable the vdev scheduler.
The intention behind this property is to improve IOPS
performance when using o_direct.

Reviewed-by: Tony Hutter <hutter2@llnl.gov>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Alexander Motin <alexander.motin@TrueNAS.com>
Signed-off-by: MigeljanImeri <ImeriMigel@gmail.com>
Closes #17358

module/zfs/vdev.c

@@ -767,6 +767,8 @@ vdev_alloc_common(spa_t *spa, uint_t id, uint64_t guid, vdev_ops_t *ops)
 	vd->vdev_slow_io_n = vdev_prop_default_numeric(VDEV_PROP_SLOW_IO_N);
 	vd->vdev_slow_io_t = vdev_prop_default_numeric(VDEV_PROP_SLOW_IO_T);
 
+	vd->vdev_scheduler = vdev_prop_default_numeric(VDEV_PROP_SCHEDULER);
+
 	list_link_init(&vd->vdev_config_dirty_node);
 	list_link_init(&vd->vdev_state_dirty_node);
 	list_link_init(&vd->vdev_initialize_node);
@@ -3972,6 +3974,12 @@ vdev_load(vdev_t *vd)
 		if (error && error != ENOENT)
 			vdev_dbgmsg(vd, "vdev_load: zap_lookup(zap=%llu) "
 			    "failed [error=%d]", (u_longlong_t)zapobj, error);
+
+		error = vdev_prop_get_int(vd, VDEV_PROP_SCHEDULER,
+		    &vd->vdev_scheduler);
+		if (error && error != ENOENT)
+			vdev_dbgmsg(vd, "vdev_load: zap_lookup(zap=%llu) "
+			    "failed [error=%d]", (u_longlong_t)zapobj, error);
 	}
 
 	/*
@@ -6259,6 +6267,13 @@ vdev_prop_set(vdev_t *vd, nvlist_t *innvl, nvlist_t *outnvl)
 			}
 			vd->vdev_slow_io_t = intval;
 			break;
+		case VDEV_PROP_SCHEDULER:
+			if (nvpair_value_uint64(elem, &intval) != 0) {
+				error = EINVAL;
+				break;
+			}
+			vd->vdev_scheduler = intval;
+			break;
 		default:
 			/* Most processing is done in vdev_props_set_sync */
 			break;
@@ -6664,6 +6679,7 @@ vdev_prop_get(vdev_t *vd, nvlist_t *innvl, nvlist_t *outnvl)
 			case VDEV_PROP_IO_T:
 			case VDEV_PROP_SLOW_IO_N:
 			case VDEV_PROP_SLOW_IO_T:
+			case VDEV_PROP_SCHEDULER:
 				err = vdev_prop_get_int(vd, prop, &intval);
 				if (err && err != ENOENT)
 					break;

module/zfs/vdev_file.c

@@ -109,6 +109,9 @@ vdev_file_open(vdev_t *vd, uint64_t *psize, uint64_t *max_psize,
 	 */
 	vd->vdev_nonrot = B_TRUE;
 
+	/* Is not backed by a block device. */
+	vd->vdev_is_blkdev = B_FALSE;
+
 	/*
 	 * Allow TRIM on file based vdevs.  This may not always be supported,
 	 * since it depends on your kernel version and underlying filesystem

module/zfs/vdev_queue.c

@@ -879,6 +879,38 @@ again:
 	return (zio);
 }
 
+static boolean_t
+vdev_should_queue_io(zio_t *zio)
+{
+	vdev_t *vd = zio->io_vd;
+	boolean_t should_queue = B_TRUE;
+
+	/*
+	 * Add zio with ZIO_FLAG_NODATA to queue as bypass code
+	 * currently does not handle certain cases (gang abd, raidz
+	 * write aggregation).
+	 */
+	if (zio->io_flags & ZIO_FLAG_NODATA)
+		return (B_TRUE);
+
+	switch (vd->vdev_scheduler) {
+	case VDEV_SCHEDULER_AUTO:
+		if (vd->vdev_nonrot && vd->vdev_is_blkdev)
+			should_queue = B_FALSE;
+		break;
+	case VDEV_SCHEDULER_ON:
+		should_queue = B_TRUE;
+		break;
+	case VDEV_SCHEDULER_OFF:
+		should_queue = B_FALSE;
+		break;
+	default:
+		should_queue = B_TRUE;
+		break;
+	}
+	return (should_queue);
+}
+
 zio_t *
 vdev_queue_io(zio_t *zio)
 {
@@ -922,6 +954,11 @@ vdev_queue_io(zio_t *zio)
 	zio->io_flags |= ZIO_FLAG_DONT_QUEUE;
 	zio->io_timestamp = gethrtime();
 
+	if (!vdev_should_queue_io(zio)) {
+		zio->io_queue_state = ZIO_QS_NONE;
+		return (zio);
+	}
+
 	mutex_enter(&vq->vq_lock);
 	vdev_queue_io_add(vq, zio);
 	nio = vdev_queue_io_to_issue(vq);
@@ -954,6 +991,9 @@ vdev_queue_io_done(zio_t *zio)
 	vq->vq_io_complete_ts = now;
 	vq->vq_io_delta_ts = zio->io_delta = now - zio->io_timestamp;
 
+	if (zio->io_queue_state == ZIO_QS_NONE)
+		return;
+
 	mutex_enter(&vq->vq_lock);
 	vdev_queue_pending_remove(vq, zio);