diff mbox series

[05/14] blk-mq: allow software queue to map to multiple hardware queues

Message ID 20181029163738.10172-6-axboe@kernel.dk (mailing list archive)
State Superseded
Headers show
Series blk-mq: Add support for multiple queue maps | expand

Commit Message

Jens Axboe Oct. 29, 2018, 4:37 p.m. UTC 
The mapping used to be dependent on just the CPU location, but
now it's a tuple of { type, cpu} instead. This is a prep patch
for allowing a single software queue to map to multiple hardware
queues. No functional changes in this patch.

Reviewed-by: Hannes Reinecke <hare@suse.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
---
 block/blk-mq-sched.c   |  2 +-
 block/blk-mq.c         | 18 ++++++++++++------
 block/blk-mq.h         |  2 +-
 block/kyber-iosched.c  |  6 +++---
 include/linux/blk-mq.h |  3 ++-
 5 files changed, 19 insertions(+), 12 deletions(-)

Comments

Bart Van Assche Oct. 29, 2018, 5:34 p.m. UTC | #1 
On Mon, 2018-10-29 at 10:37 -0600, Jens Axboe wrote:
> The mapping used to be dependent on just the CPU location, but
> now it's a tuple of { type, cpu} instead. This is a prep patch
> for allowing a single software queue to map to multiple hardware
> queues. No functional changes in this patch.

A nitpick: mathematicians usually use the { } notation for sets and () for
tuples. See also https://en.wikipedia.org/wiki/Tuple.

> +		/* wrap */
> +		BUG_ON(!hctx->nr_ctx);

Another nitpick: how about changing the "wrap" comment into "detect integer
overflow" or so to make the purpose of the BUG_ON() statement more clear?

Thanks,

Bart.
Jens Axboe Oct. 29, 2018, 5:35 p.m. UTC | #2 
On 10/29/18 11:34 AM, Bart Van Assche wrote:
> On Mon, 2018-10-29 at 10:37 -0600, Jens Axboe wrote:
>> The mapping used to be dependent on just the CPU location, but
>> now it's a tuple of { type, cpu} instead. This is a prep patch
>> for allowing a single software queue to map to multiple hardware
>> queues. No functional changes in this patch.
> 
> A nitpick: mathematicians usually use the { } notation for sets and () for
> tuples. See also https://en.wikipedia.org/wiki/Tuple.

Alright :-)

>> +		/* wrap */
>> +		BUG_ON(!hctx->nr_ctx);
> 
> Another nitpick: how about changing the "wrap" comment into "detect integer
> overflow" or so to make the purpose of the BUG_ON() statement more clear?

Sure, I'll improve that one too.
diff mbox series

Patch

diff --git a/block/blk-mq-sched.c b/block/blk-mq-sched.c
index 8125e9393ec2..d232ecf3290c 100644
--- a/block/blk-mq-sched.c
+++ b/block/blk-mq-sched.c
@@ -110,7 +110,7 @@  static void blk_mq_do_dispatch_sched(struct blk_mq_hw_ctx *hctx)
 static struct blk_mq_ctx *blk_mq_next_ctx(struct blk_mq_hw_ctx *hctx,
 					  struct blk_mq_ctx *ctx)
 {
-	unsigned idx = ctx->index_hw;
+	unsigned short idx = ctx->index_hw[hctx->type];
 
 	if (++idx == hctx->nr_ctx)
 		idx = 0;
diff --git a/block/blk-mq.c b/block/blk-mq.c
index e6ea7da99125..fab84c6bda18 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -75,14 +75,18 @@  static bool blk_mq_hctx_has_pending(struct blk_mq_hw_ctx *hctx)
 static void blk_mq_hctx_mark_pending(struct blk_mq_hw_ctx *hctx,
 				     struct blk_mq_ctx *ctx)
 {
-	if (!sbitmap_test_bit(&hctx->ctx_map, ctx->index_hw))
-		sbitmap_set_bit(&hctx->ctx_map, ctx->index_hw);
+	const int bit = ctx->index_hw[hctx->type];
+
+	if (!sbitmap_test_bit(&hctx->ctx_map, bit))
+		sbitmap_set_bit(&hctx->ctx_map, bit);
 }
 
 static void blk_mq_hctx_clear_pending(struct blk_mq_hw_ctx *hctx,
 				      struct blk_mq_ctx *ctx)
 {
-	sbitmap_clear_bit(&hctx->ctx_map, ctx->index_hw);
+	const int bit = ctx->index_hw[hctx->type];
+
+	sbitmap_clear_bit(&hctx->ctx_map, bit);
 }
 
 struct mq_inflight {
@@ -954,7 +958,7 @@  static bool dispatch_rq_from_ctx(struct sbitmap *sb, unsigned int bitnr,
 struct request *blk_mq_dequeue_from_ctx(struct blk_mq_hw_ctx *hctx,
 					struct blk_mq_ctx *start)
 {
-	unsigned off = start ? start->index_hw : 0;
+	unsigned off = start ? start->index_hw[hctx->type] : 0;
 	struct dispatch_rq_data data = {
 		.hctx = hctx,
 		.rq   = NULL,
@@ -2342,10 +2346,12 @@  static void blk_mq_map_swqueue(struct request_queue *q)
 
 		ctx = per_cpu_ptr(q->queue_ctx, i);
 		hctx = blk_mq_map_queue_type(q, 0, i);
-
+		hctx->type = 0;
 		cpumask_set_cpu(i, hctx->cpumask);
-		ctx->index_hw = hctx->nr_ctx;
+		ctx->index_hw[hctx->type] = hctx->nr_ctx;
 		hctx->ctxs[hctx->nr_ctx++] = ctx;
+		/* wrap */
+		BUG_ON(!hctx->nr_ctx);
 	}
 
 	mutex_unlock(&q->sysfs_lock);
diff --git a/block/blk-mq.h b/block/blk-mq.h
index 55428b92c019..7b5a790acdbf 100644
--- a/block/blk-mq.h
+++ b/block/blk-mq.h
@@ -17,7 +17,7 @@  struct blk_mq_ctx {
 	}  ____cacheline_aligned_in_smp;
 
 	unsigned int		cpu;
-	unsigned int		index_hw;
+	unsigned short		index_hw[HCTX_MAX_TYPES];
 
 	/* incremented at dispatch time */
 	unsigned long		rq_dispatched[2];
diff --git a/block/kyber-iosched.c b/block/kyber-iosched.c
index 728757a34fa0..b824a639d5d4 100644
--- a/block/kyber-iosched.c
+++ b/block/kyber-iosched.c
@@ -576,7 +576,7 @@  static bool kyber_bio_merge(struct blk_mq_hw_ctx *hctx, struct bio *bio)
 {
 	struct kyber_hctx_data *khd = hctx->sched_data;
 	struct blk_mq_ctx *ctx = blk_mq_get_ctx(hctx->queue);
-	struct kyber_ctx_queue *kcq = &khd->kcqs[ctx->index_hw];
+	struct kyber_ctx_queue *kcq = &khd->kcqs[ctx->index_hw[hctx->type]];
 	unsigned int sched_domain = kyber_sched_domain(bio->bi_opf);
 	struct list_head *rq_list = &kcq->rq_list[sched_domain];
 	bool merged;
@@ -602,7 +602,7 @@  static void kyber_insert_requests(struct blk_mq_hw_ctx *hctx,
 
 	list_for_each_entry_safe(rq, next, rq_list, queuelist) {
 		unsigned int sched_domain = kyber_sched_domain(rq->cmd_flags);
-		struct kyber_ctx_queue *kcq = &khd->kcqs[rq->mq_ctx->index_hw];
+		struct kyber_ctx_queue *kcq = &khd->kcqs[rq->mq_ctx->index_hw[hctx->type]];
 		struct list_head *head = &kcq->rq_list[sched_domain];
 
 		spin_lock(&kcq->lock);
@@ -611,7 +611,7 @@  static void kyber_insert_requests(struct blk_mq_hw_ctx *hctx,
 		else
 			list_move_tail(&rq->queuelist, head);
 		sbitmap_set_bit(&khd->kcq_map[sched_domain],
-				rq->mq_ctx->index_hw);
+				rq->mq_ctx->index_hw[hctx->type]);
 		blk_mq_sched_request_inserted(rq);
 		spin_unlock(&kcq->lock);
 	}
diff --git a/include/linux/blk-mq.h b/include/linux/blk-mq.h
index 71fd205b4213..f9e19962a22f 100644
--- a/include/linux/blk-mq.h
+++ b/include/linux/blk-mq.h
@@ -37,7 +37,8 @@  struct blk_mq_hw_ctx {
 	struct blk_mq_ctx	*dispatch_from;
 	unsigned int		dispatch_busy;
 
-	unsigned int		nr_ctx;
+	unsigned short		type;
+	unsigned short		nr_ctx;
 	struct blk_mq_ctx	**ctxs;
 
 	spinlock_t		dispatch_wait_lock;