blk-mq: allow software queue to map to multiple hardware queues
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.
This changes the software queue count to an unsigned short
to save a bit of space. We can still support 64K-1 CPUs,
which should be enough. Add a check to catch a wrap.
Reviewed-by: Hannes Reinecke <[email protected]>
Reviewed-by: Keith Busch <[email protected]>
Signed-off-by: Jens Axboe <[email protected]>
diff --git a/block/blk-mq-sched.c b/block/blk-mq-sched.c
index 68087bf..bbabc38 100644
--- a/block/blk-mq-sched.c
+++ b/block/blk-mq-sched.c
@@ -109,7 +109,7 @@ 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 67dec64..31976bf 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 {
@@ -955,7 +959,7 @@ 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,
@@ -2343,10 +2347,16 @@ 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;
+
+ /*
+ * If the nr_ctx type overflows, we have exceeded the
+ * amount of sw queues we can support.
+ */
+ BUG_ON(!hctx->nr_ctx);
}
mutex_unlock(&q->sysfs_lock);
diff --git a/block/blk-mq.h b/block/blk-mq.h
index 6a8f8b6..1821f44 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 1fd83a9..de78e8a 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 1761648..6c39d54 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;
