Merge struct nvme_prp_list into struct nvme_tracker.

This simplifies the driver significantly where it is constructing
commands to be submitted to hardware.  By reducing the number of
PRPs (NVMe parlance for SGE) from 128 to 32, it ensures we do not
allocate too much memory for more common smaller I/O sizes, while
still supporting up to 128KB I/O sizes.

This also paves the way for pre-allocation of nvme_tracker objects
for each queue which will simplify the I/O path even further.

Sponsored by:	Intel

1 files changed, 11 insertions, 42 deletions

diff --git a/sys/dev/nvme/nvme_qpair.c b/sys/dev/nvme/nvme_qpair.c
index efe5055..8d416e3 100644
--- a/sys/dev/nvme/nvme_qpair.c
+++ b/sys/dev/nvme/nvme_qpair.c
@@ -75,10 +75,9 @@ nvme_completion_check_retry(const struct nvme_completion *cpl)
 }
 
 struct nvme_tracker *
-nvme_qpair_allocate_tracker(struct nvme_qpair *qpair, boolean_t alloc_prp_list)
+nvme_qpair_allocate_tracker(struct nvme_qpair *qpair)
 {
 	struct nvme_tracker	*tr;
-	struct nvme_prp_list	*prp_list;
 
 	mtx_lock(&qpair->lock);
 
@@ -102,33 +101,17 @@ nvme_qpair_allocate_tracker(struct nvme_qpair *qpair, boolean_t alloc_prp_list)
 			return (NULL);
 		}
 
-		bus_dmamap_create(qpair->dma_tag, 0, &tr->dma_map);
+		bus_dmamap_create(qpair->dma_tag, 0, &tr->payload_dma_map);
+		bus_dmamap_create(qpair->dma_tag, 0, &tr->prp_dma_map);
+
+		bus_dmamap_load(qpair->dma_tag, tr->prp_dma_map, tr->prp,
+		    sizeof(tr->prp), nvme_single_map, &tr->prp_bus_addr, 0);
+
 		callout_init_mtx(&tr->timer, &qpair->lock, 0);
 		tr->cid = qpair->num_tr++;
 	} else
 		SLIST_REMOVE_HEAD(&qpair->free_tr, slist);
 
-	if (alloc_prp_list) {
-		prp_list = SLIST_FIRST(&qpair->free_prp_list);
-
-		if (prp_list == NULL) {
-			prp_list = malloc(sizeof(struct nvme_prp_list),
-			    M_NVME, M_ZERO | M_NOWAIT);
-
-			bus_dmamap_create(qpair->dma_tag, 0, &prp_list->dma_map);
-
-			bus_dmamap_load(qpair->dma_tag, prp_list->dma_map,
-			    prp_list->prp, sizeof(struct nvme_prp_list),
-			    nvme_single_map, &prp_list->bus_addr, 0);
-
-			qpair->num_prp_list++;
-		} else {
-			SLIST_REMOVE_HEAD(&qpair->free_prp_list, slist);
-		}
-
-		tr->prp_list = prp_list;
-	}
-
 	return (tr);
 }
 
@@ -176,14 +159,9 @@ nvme_qpair_process_completions(struct nvme_qpair *qpair)
 			/* nvme_qpair_submit_cmd() will release the lock. */
 			nvme_qpair_submit_cmd(qpair, tr);
 		else {
-			if (tr->prp_list) {
-				SLIST_INSERT_HEAD(&qpair->free_prp_list,
-				    tr->prp_list, slist);
-				tr->prp_list = NULL;
-			}
-
 			if (tr->payload_size > 0)
-				bus_dmamap_unload(qpair->dma_tag, tr->dma_map);
+				bus_dmamap_unload(qpair->dma_tag,
+				    tr->payload_dma_map);
 
 			SLIST_INSERT_HEAD(&qpair->free_tr, tr, slist);
 
@@ -256,7 +234,6 @@ nvme_qpair_construct(struct nvme_qpair *qpair, uint32_t id,
 	qpair->num_cmds = 0;
 	qpair->num_intr_handler_calls = 0;
 	qpair->num_tr = 0;
-	qpair->num_prp_list = 0;
 	qpair->sq_head = qpair->sq_tail = qpair->cq_head = 0;
 
 	/* TODO: error checking on contigmalloc, bus_dmamap_load calls */
@@ -281,7 +258,6 @@ nvme_qpair_construct(struct nvme_qpair *qpair, uint32_t id,
 	qpair->cq_hdbl_off = nvme_mmio_offsetof(doorbell[id].cq_hdbl);
 
 	SLIST_INIT(&qpair->free_tr);
-	SLIST_INIT(&qpair->free_prp_list);
 
 	qpair->act_tr = malloc(sizeof(struct nvme_tracker *) * qpair->num_entries,
 	    M_NVME, M_ZERO | M_NOWAIT);
@@ -291,7 +267,6 @@ static void
 nvme_qpair_destroy(struct nvme_qpair *qpair)
 {
 	struct nvme_tracker *tr;
-	struct nvme_prp_list *prp_list;
 
 	if (qpair->tag)
 		bus_teardown_intr(qpair->ctrlr->dev, qpair->res, qpair->tag);
@@ -309,16 +284,10 @@ nvme_qpair_destroy(struct nvme_qpair *qpair)
 	while (!SLIST_EMPTY(&qpair->free_tr)) {
 		tr = SLIST_FIRST(&qpair->free_tr);
 		SLIST_REMOVE_HEAD(&qpair->free_tr, slist);
-		bus_dmamap_destroy(qpair->dma_tag, tr->dma_map);
+		bus_dmamap_destroy(qpair->dma_tag, tr->payload_dma_map);
+		bus_dmamap_destroy(qpair->dma_tag, tr->prp_dma_map);
 		free(tr, M_NVME);
 	}
-
-	while (!SLIST_EMPTY(&qpair->free_prp_list)) {
-		prp_list = SLIST_FIRST(&qpair->free_prp_list);
-		SLIST_REMOVE_HEAD(&qpair->free_prp_list, slist);
-		bus_dmamap_destroy(qpair->dma_tag, prp_list->dma_map);
-		free(prp_list, M_NVME);
-	}
 }
 
 void