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blk-mq: allow software queue to map to multiple hardware queues

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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 <hare@suse.com>
Reviewed-by: Keith Busch <keith.busch@intel.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Jens Axboe 2018-10-29 13:13:29 -06:00
parent f9afca4d36
commit f31967f0e4
5 changed files with 23 additions and 12 deletions
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2
block/blk-mq-sched.c
View File

@ -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;

22
block/blk-mq.c
View File

@ -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);

2
block/blk-mq.h
View File

@ -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];

6
block/kyber-iosched.c
View File

@ -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);
}

3
include/linux/blk-mq.h
View File

@ -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;