diff options
| -rw-r--r-- | block/blk-mq.c | 66 | ||||
| -rw-r--r-- | block/kyber-iosched.c | 1 | ||||
| -rw-r--r-- | include/linux/elevator.h | 2 |
3 files changed, 63 insertions, 6 deletions
diff --git a/block/blk-mq.c b/block/blk-mq.c index 1af6b8a9da5a..f21d922ecfaf 100644 --- a/block/blk-mq.c +++ b/block/blk-mq.c @@ -1646,6 +1646,42 @@ void blk_mq_run_hw_queue(struct blk_mq_hw_ctx *hctx, bool async) } EXPORT_SYMBOL(blk_mq_run_hw_queue); +/* + * Is the request queue handled by an IO scheduler that does not respect + * hardware queues when dispatching? + */ +static bool blk_mq_has_sqsched(struct request_queue *q) +{ + struct elevator_queue *e = q->elevator; + + if (e && e->type->ops.dispatch_request && + !(e->type->elevator_features & ELEVATOR_F_MQ_AWARE)) + return true; + return false; +} + +/* + * Return prefered queue to dispatch from (if any) for non-mq aware IO + * scheduler. + */ +static struct blk_mq_hw_ctx *blk_mq_get_sq_hctx(struct request_queue *q) +{ + struct blk_mq_hw_ctx *hctx; + + /* + * If the IO scheduler does not respect hardware queues when + * dispatching, we just don't bother with multiple HW queues and + * dispatch from hctx for the current CPU since running multiple queues + * just causes lock contention inside the scheduler and pointless cache + * bouncing. + */ + hctx = blk_mq_map_queue_type(q, HCTX_TYPE_DEFAULT, + raw_smp_processor_id()); + if (!blk_mq_hctx_stopped(hctx)) + return hctx; + return NULL; +} + /** * blk_mq_run_hw_queues - Run all hardware queues in a request queue. * @q: Pointer to the request queue to run. @@ -1653,14 +1689,23 @@ EXPORT_SYMBOL(blk_mq_run_hw_queue); */ void blk_mq_run_hw_queues(struct request_queue *q, bool async) { - struct blk_mq_hw_ctx *hctx; + struct blk_mq_hw_ctx *hctx, *sq_hctx; int i; + sq_hctx = NULL; + if (blk_mq_has_sqsched(q)) + sq_hctx = blk_mq_get_sq_hctx(q); queue_for_each_hw_ctx(q, hctx, i) { if (blk_mq_hctx_stopped(hctx)) continue; - - blk_mq_run_hw_queue(hctx, async); + /* + * Dispatch from this hctx either if there's no hctx preferred + * by IO scheduler or if it has requests that bypass the + * scheduler. + */ + if (!sq_hctx || sq_hctx == hctx || + !list_empty_careful(&hctx->dispatch)) + blk_mq_run_hw_queue(hctx, async); } } EXPORT_SYMBOL(blk_mq_run_hw_queues); @@ -1672,14 +1717,23 @@ EXPORT_SYMBOL(blk_mq_run_hw_queues); */ void blk_mq_delay_run_hw_queues(struct request_queue *q, unsigned long msecs) { - struct blk_mq_hw_ctx *hctx; + struct blk_mq_hw_ctx *hctx, *sq_hctx; int i; + sq_hctx = NULL; + if (blk_mq_has_sqsched(q)) + sq_hctx = blk_mq_get_sq_hctx(q); queue_for_each_hw_ctx(q, hctx, i) { if (blk_mq_hctx_stopped(hctx)) continue; - - blk_mq_delay_run_hw_queue(hctx, msecs); + /* + * Dispatch from this hctx either if there's no hctx preferred + * by IO scheduler or if it has requests that bypass the + * scheduler. + */ + if (!sq_hctx || sq_hctx == hctx || + !list_empty_careful(&hctx->dispatch)) + blk_mq_delay_run_hw_queue(hctx, msecs); } } EXPORT_SYMBOL(blk_mq_delay_run_hw_queues); diff --git a/block/kyber-iosched.c b/block/kyber-iosched.c index dc89199bc8c6..c25c41d0d061 100644 --- a/block/kyber-iosched.c +++ b/block/kyber-iosched.c @@ -1029,6 +1029,7 @@ static struct elevator_type kyber_sched = { #endif .elevator_attrs = kyber_sched_attrs, .elevator_name = "kyber", + .elevator_features = ELEVATOR_F_MQ_AWARE, .elevator_owner = THIS_MODULE, }; diff --git a/include/linux/elevator.h b/include/linux/elevator.h index bacc40a0bdf3..1fe8e105b83b 100644 --- a/include/linux/elevator.h +++ b/include/linux/elevator.h @@ -172,6 +172,8 @@ extern struct request *elv_rb_find(struct rb_root *, sector_t); /* Supports zoned block devices sequential write constraint */ #define ELEVATOR_F_ZBD_SEQ_WRITE (1U << 0) +/* Supports scheduling on multiple hardware queues */ +#define ELEVATOR_F_MQ_AWARE (1U << 1) #endif /* CONFIG_BLOCK */ #endif |