From: Yu Kuai <yukuai3@huawei.com>
blkcg_bio_issue_init() is called for every bio, while initialized
bio_issue_time is only used by io-latency. Add a new queue_flag and
only set this flag when io-latency is initialized, so that extra
blk_time_get_ns() from blkcg_bio_issue_init() can be saved for disks
that io-latency is not enabled.
Signed-off-by: Yu Kuai <yukuai3@huawei.com>
---
block/blk-cgroup.h | 5 ++++-
block/blk-iolatency.c | 1 +
block/blk-mq-debugfs.c | 1 +
include/linux/blkdev.h | 1 +
4 files changed, 7 insertions(+), 1 deletion(-)
diff --git a/block/blk-cgroup.h b/block/blk-cgroup.h
index d73204d27d72..93e8a9fa76fe 100644
--- a/block/blk-cgroup.h
+++ b/block/blk-cgroup.h
@@ -372,7 +372,10 @@ static inline void blkg_put(struct blkcg_gq *blkg)
static inline void blkcg_bio_issue_init(struct bio *bio)
{
- bio->issue_time_ns = blk_time_get_ns();
+ struct request_queue *q = bdev_get_queue(bio->bi_bdev);
+
+ if (test_bit(QUEUE_FLAG_BIO_ISSUE, &q->queue_flags))
+ bio->issue_time_ns = blk_time_get_ns();
}
static inline void blkcg_use_delay(struct blkcg_gq *blkg)
diff --git a/block/blk-iolatency.c b/block/blk-iolatency.c
index 554b191a6892..c9b3bd12c87c 100644
--- a/block/blk-iolatency.c
+++ b/block/blk-iolatency.c
@@ -767,6 +767,7 @@ static int blk_iolatency_init(struct gendisk *disk)
if (ret)
goto err_qos_del;
+ blk_queue_flag_set(QUEUE_FLAG_BIO_ISSUE, disk->queue);
timer_setup(&blkiolat->timer, blkiolatency_timer_fn, 0);
INIT_WORK(&blkiolat->enable_work, blkiolatency_enable_work_fn);
diff --git a/block/blk-mq-debugfs.c b/block/blk-mq-debugfs.c
index 32c65efdda46..b192647456e1 100644
--- 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),
};
#undef QUEUE_FLAG_NAME
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index fe1797bbec42..ca1dcf59cb32 100644
--- 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, /* track bio issue time */
QUEUE_FLAG_MAX
};
--
2.39.2On Mon, Sep 01, 2025 at 11:32:07AM +0800, Yu Kuai wrote:
> static inline void blkcg_bio_issue_init(struct bio *bio)
> {
> - bio->issue_time_ns = blk_time_get_ns();
> + struct request_queue *q = bdev_get_queue(bio->bi_bdev);
> +
> + if (test_bit(QUEUE_FLAG_BIO_ISSUE, &q->queue_flags))
> + bio->issue_time_ns = blk_time_get_ns();
> }
Given that this is called on a bio and called from generic code
and not blk-mq, the flag should in the gendisk and not the queue.
Hi,
在 2025/9/3 21:24, Christoph Hellwig 写道:
> On Mon, Sep 01, 2025 at 11:32:07AM +0800, Yu Kuai wrote:
>> static inline void blkcg_bio_issue_init(struct bio *bio)
>> {
>> - bio->issue_time_ns = blk_time_get_ns();
>> + struct request_queue *q = bdev_get_queue(bio->bi_bdev);
>> +
>> + if (test_bit(QUEUE_FLAG_BIO_ISSUE, &q->queue_flags))
>> + bio->issue_time_ns = blk_time_get_ns();
>> }
> Given that this is called on a bio and called from generic code
> and not blk-mq, the flag should in the gendisk and not the queue.
>
ok, will change to disk, and also change set/clear the flag to
enable/disable iolatency.
Thanks,
Kuai
Hi,
在 2025/09/04 0:54, Yu Kuai 写道:
> Hi,
>
> 在 2025/9/3 21:24, Christoph Hellwig 写道:
>> On Mon, Sep 01, 2025 at 11:32:07AM +0800, Yu Kuai wrote:
>>> static inline void blkcg_bio_issue_init(struct bio *bio)
>>> {
>>> - bio->issue_time_ns = blk_time_get_ns();
>>> + struct request_queue *q = bdev_get_queue(bio->bi_bdev);
>>> +
>>> + if (test_bit(QUEUE_FLAG_BIO_ISSUE, &q->queue_flags))
>>> + bio->issue_time_ns = blk_time_get_ns();
>>> }
>> Given that this is called on a bio and called from generic code
>> and not blk-mq, the flag should in the gendisk and not the queue.
>>
> ok, will change to disk, and also change set/clear the flag to
> enable/disable iolatency.
After careful consideration, I think it's better to delay
blkcg_bio_issue_init() to blk_mq_submit_bio():
- it's only used by iolatency, which can only be enabled for rq-based
disks;
- For bio that is submitted the first time, blk_cgroup_bio_start() is
called from submit_bio_no_acct_nocheck(), where q_usage_counter is not
grabbed yet, hence it's not safe to enable that flag while enabling
iolatency.
diff --git a/block/blk-core.c b/block/blk-core.c
index 4201504158a1..83c262a3dfd9 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -728,7 +728,6 @@ static void __submit_bio_noacct_mq(struct bio *bio)
void submit_bio_noacct_nocheck(struct bio *bio)
{
blk_cgroup_bio_start(bio);
- blkcg_bio_issue_init(bio);
if (!bio_flagged(bio, BIO_TRACE_COMPLETION)) {
trace_block_bio_queue(bio);
diff --git a/block/blk-merge.c b/block/blk-merge.c
index 70d704615be5..5538356770a4 100644
--- a/block/blk-merge.c
+++ b/block/blk-merge.c
@@ -119,7 +119,6 @@ static struct bio *bio_submit_split(struct bio *bio,
int split_sectors)
goto error;
}
split->bi_opf |= REQ_NOMERGE;
- blkcg_bio_issue_init(split);
bio_chain(split, bio);
trace_block_split(split, bio->bi_iter.bi_sector);
WARN_ON_ONCE(bio_zone_write_plugging(bio));
diff --git a/block/blk-mq.c b/block/blk-mq.c
index ba3a4b77f578..030937b129a2 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -3108,7 +3108,7 @@ static bool bio_unaligned(const struct bio *bio,
struct request_queue *q)
* It will not queue the request if there is an error with the bio, or
at the
* request creation.
*/
-void blk_mq_submit_bio(struct bio *bio)
+void b k_mq_submit_bio(struct bio *bio)
{
struct request_queue *q = bdev_get_queue(bio->bi_bdev);
struct blk_plug *plug = current->plug;
@@ -3168,6 +3168,9 @@ void blk_mq_submit_bio(struct bio *bio)
if (!bio_integrity_prep(bio))
goto queue_exit;
+ if (test_bit(QUEUE_FLAG_BIO_ISSUE, &q->queue_flags))
+ bio->issue_time_ns = blk_time_get_ns();
+
if (blk_mq_attempt_bio_merge(q, bio, nr_segs))
goto queue_exit;
>
> Thanks,
> Kuai
>
> .
>
On Thu, Sep 04, 2025 at 10:44:32AM +0800, Yu Kuai wrote: > - it's only used by iolatency, which can only be enabled for rq-based > disks; > - For bio that is submitted the first time, blk_cgroup_bio_start() is > called from submit_bio_no_acct_nocheck(), where q_usage_counter is not > grabbed yet, hence it's not safe to enable that flag while enabling > iolatency. Yes, keeping more things in blk-mq is always good. > -void blk_mq_submit_bio(struct bio *bio) > +void b k_mq_submit_bio(struct bio *bio) This got mangled somehow.
On 8/31/25 8:32 PM, Yu Kuai wrote:
> @@ -372,7 +372,10 @@ static inline void blkg_put(struct blkcg_gq *blkg)
>
> static inline void blkcg_bio_issue_init(struct bio *bio)
> {
> - bio->issue_time_ns = blk_time_get_ns();
> + struct request_queue *q = bdev_get_queue(bio->bi_bdev);
> +
> + if (test_bit(QUEUE_FLAG_BIO_ISSUE, &q->queue_flags))
> + bio->issue_time_ns = blk_time_get_ns();
> }
>
> static inline void blkcg_use_delay(struct blkcg_gq *blkg)
> diff --git a/block/blk-iolatency.c b/block/blk-iolatency.c
> index 554b191a6892..c9b3bd12c87c 100644
> --- a/block/blk-iolatency.c
> +++ b/block/blk-iolatency.c
> @@ -767,6 +767,7 @@ static int blk_iolatency_init(struct gendisk *disk)
> if (ret)
> goto err_qos_del;
>
> + blk_queue_flag_set(QUEUE_FLAG_BIO_ISSUE, disk->queue);
> timer_setup(&blkiolat->timer, blkiolatency_timer_fn, 0);
> INIT_WORK(&blkiolat->enable_work, blkiolatency_enable_work_fn);
Shouldn't QUEUE_FLAG_BIO_ISSUE be cleared when initializing
bio->issue_time_ns is no longer necessary?
Thanks,
Bart.
Hi,
在 2025/09/03 1:05, Bart Van Assche 写道:
> On 8/31/25 8:32 PM, Yu Kuai wrote:
>> @@ -372,7 +372,10 @@ static inline void blkg_put(struct blkcg_gq *blkg)
>> static inline void blkcg_bio_issue_init(struct bio *bio)
>> {
>> - bio->issue_time_ns = blk_time_get_ns();
>> + struct request_queue *q = bdev_get_queue(bio->bi_bdev);
>> +
>> + if (test_bit(QUEUE_FLAG_BIO_ISSUE, &q->queue_flags))
>> + bio->issue_time_ns = blk_time_get_ns();
>> }
>> static inline void blkcg_use_delay(struct blkcg_gq *blkg)
>> diff --git a/block/blk-iolatency.c b/block/blk-iolatency.c
>> index 554b191a6892..c9b3bd12c87c 100644
>> --- a/block/blk-iolatency.c
>> +++ b/block/blk-iolatency.c
>> @@ -767,6 +767,7 @@ static int blk_iolatency_init(struct gendisk *disk)
>> if (ret)
>> goto err_qos_del;
>> + blk_queue_flag_set(QUEUE_FLAG_BIO_ISSUE, disk->queue);
>> timer_setup(&blkiolat->timer, blkiolatency_timer_fn, 0);
>> INIT_WORK(&blkiolat->enable_work, blkiolatency_enable_work_fn);
>
> Shouldn't QUEUE_FLAG_BIO_ISSUE be cleared when initializing
> bio->issue_time_ns is no longer necessary?
>
iolatency can never be freed after it's initialized, however, I can add
and clear this flag in blkiolatency_enable_work_fn() instead, when
iolatency is really enabled or discabled.
Thanks,
Kuai
> Thanks,
>
> Bart.
>
> .
>
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