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authorOmar Sandoval <osandov@fb.com>2017-02-22 10:58:30 -0800
committerJens Axboe <axboe@fb.com>2017-02-23 11:55:47 -0700
commitd38d35155514ceef5efb79f6d5b4f0f1638da5b4 (patch)
treeea9eb2e3a10f286ec6813026d6a52a4483602cd4 /block
parentda55f2cc78418dee88400aafbbaed19d7ac8188e (diff)
downloadlwn-d38d35155514ceef5efb79f6d5b4f0f1638da5b4.tar.gz
lwn-d38d35155514ceef5efb79f6d5b4f0f1638da5b4.zip
blk-mq-sched: separate mark hctx and queue restart operations
In blk_mq_sched_dispatch_requests(), we call blk_mq_sched_mark_restart() after we dispatch requests left over on our hardware queue dispatch list. This is so we'll go back and dispatch requests from the scheduler. In this case, it's only necessary to restart the hardware queue that we are running; there's no reason to run other hardware queues just because we are using shared tags. So, split out blk_mq_sched_mark_restart() into two operations, one for just the hardware queue and one for the whole request queue. The core code only needs the hctx variant, but I/O schedulers will want to use both. This also requires adjusting blk_mq_sched_restart_queues() to always check the queue restart flag, not just when using shared tags. Signed-off-by: Omar Sandoval <osandov@fb.com> Signed-off-by: Jens Axboe <axboe@fb.com>
Diffstat (limited to 'block')
-rw-r--r--block/blk-mq-sched.c20
-rw-r--r--block/blk-mq-sched.h26
2 files changed, 26 insertions, 20 deletions
diff --git a/block/blk-mq-sched.c b/block/blk-mq-sched.c
index c14f92308244..98c7b061781e 100644
--- a/block/blk-mq-sched.c
+++ b/block/blk-mq-sched.c
@@ -205,7 +205,7 @@ void blk_mq_sched_dispatch_requests(struct blk_mq_hw_ctx *hctx)
* needing a restart in that case.
*/
if (!list_empty(&rq_list)) {
- blk_mq_sched_mark_restart(hctx);
+ blk_mq_sched_mark_restart_hctx(hctx);
did_work = blk_mq_dispatch_rq_list(hctx, &rq_list);
} else if (!has_sched_dispatch) {
blk_mq_flush_busy_ctxs(hctx, &rq_list);
@@ -331,20 +331,16 @@ static void blk_mq_sched_restart_hctx(struct blk_mq_hw_ctx *hctx)
void blk_mq_sched_restart_queues(struct blk_mq_hw_ctx *hctx)
{
+ struct request_queue *q = hctx->queue;
unsigned int i;
- if (!(hctx->flags & BLK_MQ_F_TAG_SHARED))
+ if (test_bit(QUEUE_FLAG_RESTART, &q->queue_flags)) {
+ if (test_and_clear_bit(QUEUE_FLAG_RESTART, &q->queue_flags)) {
+ queue_for_each_hw_ctx(q, hctx, i)
+ blk_mq_sched_restart_hctx(hctx);
+ }
+ } else {
blk_mq_sched_restart_hctx(hctx);
- else {
- struct request_queue *q = hctx->queue;
-
- if (!test_bit(QUEUE_FLAG_RESTART, &q->queue_flags))
- return;
-
- clear_bit(QUEUE_FLAG_RESTART, &q->queue_flags);
-
- queue_for_each_hw_ctx(q, hctx, i)
- blk_mq_sched_restart_hctx(hctx);
}
}
diff --git a/block/blk-mq-sched.h b/block/blk-mq-sched.h
index 7b5f3b95c78e..a75b16b123f7 100644
--- a/block/blk-mq-sched.h
+++ b/block/blk-mq-sched.h
@@ -122,17 +122,27 @@ static inline bool blk_mq_sched_has_work(struct blk_mq_hw_ctx *hctx)
return false;
}
-static inline void blk_mq_sched_mark_restart(struct blk_mq_hw_ctx *hctx)
+/*
+ * Mark a hardware queue as needing a restart.
+ */
+static inline void blk_mq_sched_mark_restart_hctx(struct blk_mq_hw_ctx *hctx)
{
- if (!test_bit(BLK_MQ_S_SCHED_RESTART, &hctx->state)) {
+ if (!test_bit(BLK_MQ_S_SCHED_RESTART, &hctx->state))
set_bit(BLK_MQ_S_SCHED_RESTART, &hctx->state);
- if (hctx->flags & BLK_MQ_F_TAG_SHARED) {
- struct request_queue *q = hctx->queue;
+}
+
+/*
+ * Mark a hardware queue and the request queue it belongs to as needing a
+ * restart.
+ */
+static inline void blk_mq_sched_mark_restart_queue(struct blk_mq_hw_ctx *hctx)
+{
+ struct request_queue *q = hctx->queue;
- if (!test_bit(QUEUE_FLAG_RESTART, &q->queue_flags))
- set_bit(QUEUE_FLAG_RESTART, &q->queue_flags);
- }
- }
+ if (!test_bit(BLK_MQ_S_SCHED_RESTART, &hctx->state))
+ set_bit(BLK_MQ_S_SCHED_RESTART, &hctx->state);
+ if (!test_bit(QUEUE_FLAG_RESTART, &q->queue_flags))
+ set_bit(QUEUE_FLAG_RESTART, &q->queue_flags);
}
static inline bool blk_mq_sched_needs_restart(struct blk_mq_hw_ctx *hctx)