blk-mq: add QUEUE_FLAG_BIO_ISSUE_TIME

bio->issue_time_ns is initialized for every bio, however, it's only used
by blk-iolatency. Add a new queue_flag and only set this flag when
blk-iolatency is enabled, so that extra blk_time_get_ns() can be saved
for disks that blk-iolatency is not enabled.

Signed-off-by: Yu Kuai <yukuai3@huawei.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/block/blk-iolatency.c b/block/blk-iolatency.c
index 554b191a68921c1076abdd910c81d66e4cbf3bed..45bd18f68541b732c06e7cd3e814f2e72b6d1034 100644 (file)
--- a/block/blk-iolatency.c
+++ b/block/blk-iolatency.c
@@ -742,10 +742,15 @@ static void blkiolatency_enable_work_fn(struct work_struct *work)
         */
        enabled = atomic_read(&blkiolat->enable_cnt);
        if (enabled != blkiolat->enabled) {
+               struct request_queue *q = blkiolat->rqos.disk->queue;
                unsigned int memflags;
 
                memflags = blk_mq_freeze_queue(blkiolat->rqos.disk->queue);
                blkiolat->enabled = enabled;
+               if (enabled)
+                       blk_queue_flag_set(QUEUE_FLAG_BIO_ISSUE_TIME, q);
+               else
+                       blk_queue_flag_clear(QUEUE_FLAG_BIO_ISSUE_TIME, q);
                blk_mq_unfreeze_queue(blkiolat->rqos.disk->queue, memflags);
        }
 }

diff --git a/block/blk-mq-debugfs.c b/block/blk-mq-debugfs.c
index 32c65efdda46c979d69e9f0aabe0ef87bebb6b8b..4896525b1c0541d21c978f53287238dc88e4b2a1 100644 (file)
--- a/block/blk-mq-debugfs.c
+++ b/block/blk-mq-debugfs.c
@@ -96,6 +96,7 @@ static const char *const blk_queue_flag_name[] = {
        QUEUE_FLAG_NAME(DISABLE_WBT_DEF),
        QUEUE_FLAG_NAME(NO_ELV_SWITCH),
        QUEUE_FLAG_NAME(QOS_ENABLED),
+       QUEUE_FLAG_NAME(BIO_ISSUE_TIME),
 };
 #undef QUEUE_FLAG_NAME
 

diff --git a/block/blk-mq.c b/block/blk-mq.c
index 2c0c8ead70806935c678306f871aa14a9dd75292..31cc743ffad788fa77a02f01f6b7b867ad2ee68c 100644 (file)
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -396,10 +396,12 @@ static inline void blk_mq_rq_time_init(struct request *rq, u64 alloc_time_ns)
 #endif
 }
 
-static inline void blk_mq_bio_issue_init(struct bio *bio)
+static inline void blk_mq_bio_issue_init(struct request_queue *q,
+                                        struct bio *bio)
 {
 #ifdef CONFIG_BLK_CGROUP
-       bio->issue_time_ns = blk_time_get_ns();
+       if (test_bit(QUEUE_FLAG_BIO_ISSUE_TIME, &q->queue_flags))
+               bio->issue_time_ns = blk_time_get_ns();
 #endif
 }
 
@@ -3175,7 +3177,7 @@ void blk_mq_submit_bio(struct bio *bio)
        if (!bio_integrity_prep(bio))
                goto queue_exit;
 
-       blk_mq_bio_issue_init(bio);
+       blk_mq_bio_issue_init(q, bio);
        if (blk_mq_attempt_bio_merge(q, bio, nr_segs))
                goto queue_exit;
 

diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index c8cb08b2ed294c15516d7ad056e98ec16329196b..7c542b1851fa863d64b732c1425059a40d3c8718 100644 (file)
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -657,6 +657,7 @@ enum {
        QUEUE_FLAG_DISABLE_WBT_DEF,     /* for sched to disable/enable wbt */
        QUEUE_FLAG_NO_ELV_SWITCH,       /* can't switch elevator any more */
        QUEUE_FLAG_QOS_ENABLED,         /* qos is enabled */
+       QUEUE_FLAG_BIO_ISSUE_TIME,      /* record bio->issue_time_ns */
        QUEUE_FLAG_MAX
 };