3 files changed, 10 insertions, 1 deletions

diff --git a/sys/dev/nvme/nvme_ctrlr.c b/sys/dev/nvme/nvme_ctrlr.c
index 85c2c35968921..95fa39fce5f47 100644
--- a/sys/dev/nvme/nvme_ctrlr.c
+++ b/sys/dev/nvme/nvme_ctrlr.c
@@ -146,6 +146,14 @@ nvme_ctrlr_construct_io_qpairs(struct nvme_controller *ctrlr)
 	num_trackers = min(num_trackers, (num_entries-1));
 
 	/*
+	 * Our best estimate for the maximum number of I/Os that we should
+	 * noramlly have in flight at one time. This should be viewed as a hint,
+	 * not a hard limit and will need to be revisitted when the upper layers
+	 * of the storage system grows multi-queue support.
+	 */
+	ctrlr->max_hw_pend_io = num_trackers * ctrlr->num_io_queues / 4;
+
+	/*
 	 * This was calculated previously when setting up interrupts, but
 	 *  a controller could theoretically support fewer I/O queues than
 	 *  MSI-X vectors.  So calculate again here just to be safe.
diff --git a/sys/dev/nvme/nvme_private.h b/sys/dev/nvme/nvme_private.h
index 487ce735ac078..8293e563cab3d 100644
--- a/sys/dev/nvme/nvme_private.h
+++ b/sys/dev/nvme/nvme_private.h
@@ -263,6 +263,7 @@ struct nvme_controller {
 
 	uint32_t		num_io_queues;
 	uint32_t		num_cpus_per_ioq;
+	uint32_t		max_hw_pend_io;
 
 	/* Fields for tracking progress during controller initialization. */
 	struct intr_config_hook	config_hook;
diff --git a/sys/dev/nvme/nvme_sim.c b/sys/dev/nvme/nvme_sim.c
index 8e89fbe755da7..6f2de462c4e74 100644
--- a/sys/dev/nvme/nvme_sim.c
+++ b/sys/dev/nvme/nvme_sim.c
@@ -253,7 +253,7 @@ nvme_sim_new_controller(struct nvme_controller *ctrlr)
 	int unit;
 	struct nvme_sim_softc *sc = NULL;
 
-	max_trans = ctrlr->num_io_queues;
+	max_trans = ctrlr->max_hw_pend_io;
 	unit = device_get_unit(ctrlr->dev);
 	devq = cam_simq_alloc(max_trans);
 	if (devq == NULL)