[PATCH v3 4/5] blk-mq: Introduce blk_mq_delay_run_hw_queue()

Bart Van Assche
2017-04-06T18:10:49Z

Introduce a function that runs a hardware queue unconditionally
after a delay. Note: there is already a function that stops and
restarts a hardware queue after a delay, namely blk_mq_delay_queue().

Signed-off-by: Bart Van Assche <bart.vanassche@sandisk.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Hannes Reinecke <hare@suse.de>
Cc: Long Li <longli@microsoft.com>
Cc: K. Y. Srinivasan <kys@microsoft.com>
---
block/blk-mq.c | 32 ++++++++++++++++++++++++++++++--
include/linux/blk-mq.h | 2 ++
2 files changed, 32 insertions(+), 2 deletions(-)

diff --git a/block/blk-mq.c b/block/blk-mq.c
index 4db48ad76878..36a80ab6fff8 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -1146,7 +1146,8 @@ static int blk_mq_hctx_next_cpu(struct blk_mq_hw_ctx *hctx)
return hctx->next_cpu;
}

-void blk_mq_run_hw_queue(struct blk_mq_hw_ctx *hctx, bool async)
+static void __blk_mq_delay_run_hw_queue(struct blk_mq_hw_ctx *hctx, bool async,
+ unsigned long msecs)
{
if (unlikely(blk_mq_hctx_stopped(hctx) ||
!blk_mq_hw_queue_mapped(hctx)))
@@ -1163,7 +1164,24 @@ void blk_mq_run_hw_queue(struct blk_mq_hw_ctx *hctx, bool async)
put_cpu();
}

- kblockd_schedule_work_on(blk_mq_hctx_next_cpu(hctx), &hctx->run_work);
+ if (msecs == 0)
+ kblockd_schedule_work_on(blk_mq_hctx_next_cpu(hctx),
+ &hctx->run_work);
+ else
+ kblockd_schedule_delayed_work_on(blk_mq_hctx_next_cpu(hctx),
+ &hctx->delayed_run_work,
+ msecs_to_jiffies(msecs));
+}
+
+void blk_mq_delay_run_hw_queue(struct blk_mq_hw_ctx *hctx, unsigned long msecs)
+{
+ __blk_mq_delay_run_hw_queue(hctx, true, msecs);
+}
+EXPORT_SYMBOL(blk_mq_delay_run_hw_queue);
+
+void blk_mq_run_hw_queue(struct blk_mq_hw_ctx *hctx, bool async)
+{
+ __blk_mq_delay_run_hw_queue(hctx, async, 0);
}

void blk_mq_run_hw_queues(struct request_queue *q, bool async)
@@ -1266,6 +1284,15 @@ static void blk_mq_run_work_fn(struct work_struct *work)
__blk_mq_run_hw_queue(hctx);
}

+static void blk_mq_delayed_run_work_fn(struct work_struct *work)
+{
+ struct blk_mq_hw_ctx *hctx;
+
+ hctx = container_of(work, struct blk_mq_hw_ctx, delayed_run_work.work);
+
+ __blk_mq_run_hw_queue(hctx);
+}
+
static void blk_mq_delay_work_fn(struct work_struct *work)
{
struct blk_mq_hw_ctx *hctx;
@@ -1866,6 +1893,7 @@ static int blk_mq_init_hctx(struct request_queue *q,
node = hctx->numa_node = set->numa_node;

INIT_WORK(&hctx->run_work, blk_mq_run_work_fn);
+ INIT_DELAYED_WORK(&hctx->delayed_run_work, blk_mq_delayed_run_work_fn);
INIT_DELAYED_WORK(&hctx->delay_work, blk_mq_delay_work_fn);
spin_lock_init(&hctx->lock);
INIT_LIST_HEAD(&hctx->dispatch);
diff --git a/include/linux/blk-mq.h b/include/linux/blk-mq.h
index bdea90d75274..b90c3d5766cd 100644
--- a/include/linux/blk-mq.h
+++ b/include/linux/blk-mq.h
@@ -51,6 +51,7 @@ struct blk_mq_hw_ctx {

atomic_t nr_active;

+ struct delayed_work delayed_run_work;
struct delayed_work delay_work;

struct hlist_node cpuhp_dead;
@@ -236,6 +237,7 @@ void blk_mq_stop_hw_queues(struct request_queue *q);
void blk_mq_start_hw_queues(struct request_queue *q);
void blk_mq_start_stopped_hw_queue(struct blk_mq_hw_ctx *hctx, bool async);
void blk_mq_start_stopped_hw_queues(struct request_queue *q, bool async);
+void blk_mq_delay_run_hw_queue(struct blk_mq_hw_ctx *hctx, unsigned long msecs);
void blk_mq_run_hw_queues(struct request_queue *q, bool async);
void blk_mq_delay_queue(struct blk_mq_hw_ctx *hctx, unsigned long msecs);
void blk_mq_tagset_busy_iter(struct blk_mq_tag_set *tagset,
--
2.12.0