* [PATCH] blk-mq-sched: don't run the queue async from blk_mq_try_issue_directly()
@ 2017-03-14 14:57 Jens Axboe
2017-03-14 15:17 ` Bart Van Assche
2017-03-14 17:48 ` Omar Sandoval
0 siblings, 2 replies; 5+ messages in thread
From: Jens Axboe @ 2017-03-14 14:57 UTC (permalink / raw)
To: linux-block
If we have scheduling enabled, we jump directly to insert-and-run.
That's fine, but we run the queue async and we don't pass in information
on whether we can block from this context or not. Fixup both these
cases.
Signed-off-by: Jens Axboe <axboe@fb.com>
diff --git a/block/blk-mq.c b/block/blk-mq.c
index 159187a28d66..4196d6bee92d 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -1434,7 +1434,8 @@ static blk_qc_t request_to_qc_t(struct blk_mq_hw_ctx *hctx, struct request *rq)
return blk_tag_to_qc_t(rq->internal_tag, hctx->queue_num, true);
}
-static void blk_mq_try_issue_directly(struct request *rq, blk_qc_t *cookie)
+static void blk_mq_try_issue_directly(struct request *rq, blk_qc_t *cookie,
+ bool can_block)
{
struct request_queue *q = rq->q;
struct blk_mq_queue_data bd = {
@@ -1475,7 +1476,7 @@ static void blk_mq_try_issue_directly(struct request *rq, blk_qc_t *cookie)
}
insert:
- blk_mq_sched_insert_request(rq, false, true, true, false);
+ blk_mq_sched_insert_request(rq, false, true, false, can_block);
}
/*
@@ -1569,11 +1570,11 @@ static blk_qc_t blk_mq_make_request(struct request_queue *q, struct bio *bio)
if (!(data.hctx->flags & BLK_MQ_F_BLOCKING)) {
rcu_read_lock();
- blk_mq_try_issue_directly(old_rq, &cookie);
+ blk_mq_try_issue_directly(old_rq, &cookie, false);
rcu_read_unlock();
} else {
srcu_idx = srcu_read_lock(&data.hctx->queue_rq_srcu);
- blk_mq_try_issue_directly(old_rq, &cookie);
+ blk_mq_try_issue_directly(old_rq, &cookie, true);
srcu_read_unlock(&data.hctx->queue_rq_srcu, srcu_idx);
}
goto done;
--
Jens Axboe
^ permalink raw reply related [flat|nested] 5+ messages in thread
* Re: [PATCH] blk-mq-sched: don't run the queue async from blk_mq_try_issue_directly()
2017-03-14 14:57 [PATCH] blk-mq-sched: don't run the queue async from blk_mq_try_issue_directly() Jens Axboe
@ 2017-03-14 15:17 ` Bart Van Assche
2017-03-14 15:26 ` Jens Axboe
2017-03-14 17:48 ` Omar Sandoval
1 sibling, 1 reply; 5+ messages in thread
From: Bart Van Assche @ 2017-03-14 15:17 UTC (permalink / raw)
To: Jens Axboe, linux-block
On 03/14/2017 07:57 AM, Jens Axboe wrote:=0A=
> If we have scheduling enabled, we jump directly to insert-and-run.=0A=
> That's fine, but we run the queue async and we don't pass in information=
=0A=
> on whether we can block from this context or not. Fixup both these=0A=
> cases.=0A=
=0A=
How about renaming "can_block" into "may_sleep"? Otherwise this patch=0A=
looks fine to me.=0A=
=0A=
Bart.=0A=
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] blk-mq-sched: don't run the queue async from blk_mq_try_issue_directly()
2017-03-14 15:17 ` Bart Van Assche
@ 2017-03-14 15:26 ` Jens Axboe
0 siblings, 0 replies; 5+ messages in thread
From: Jens Axboe @ 2017-03-14 15:26 UTC (permalink / raw)
To: Bart Van Assche, linux-block
On 03/14/2017 09:17 AM, Bart Van Assche wrote:
> On 03/14/2017 07:57 AM, Jens Axboe wrote:
>> If we have scheduling enabled, we jump directly to insert-and-run.
>> That's fine, but we run the queue async and we don't pass in information
>> on whether we can block from this context or not. Fixup both these
>> cases.
>
> How about renaming "can_block" into "may_sleep"? Otherwise this patch
> looks fine to me.
Sure, either one is fine with me, at least to me they convey the same
information.
--
Jens Axboe
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] blk-mq-sched: don't run the queue async from blk_mq_try_issue_directly()
2017-03-14 14:57 [PATCH] blk-mq-sched: don't run the queue async from blk_mq_try_issue_directly() Jens Axboe
2017-03-14 15:17 ` Bart Van Assche
@ 2017-03-14 17:48 ` Omar Sandoval
2017-03-14 17:51 ` Jens Axboe
1 sibling, 1 reply; 5+ messages in thread
From: Omar Sandoval @ 2017-03-14 17:48 UTC (permalink / raw)
To: Jens Axboe; +Cc: linux-block
On Tue, Mar 14, 2017 at 08:57:50AM -0600, Jens Axboe wrote:
> If we have scheduling enabled, we jump directly to insert-and-run.
> That's fine, but we run the queue async and we don't pass in information
> on whether we can block from this context or not. Fixup both these
> cases.
Reviewed-by: Omar Sandoval <osandov@fb.com>
Just one question: we call blk_mq_get_driver_tag() with wait=false in
blk_mq_try_issue_directly(). Should we change that to wait=can_block?
Maybe it's pointless to try a direct issue if we'd have to wait for a
tag anyways, though.
> Signed-off-by: Jens Axboe <axboe@fb.com>
>
> diff --git a/block/blk-mq.c b/block/blk-mq.c
> index 159187a28d66..4196d6bee92d 100644
> --- a/block/blk-mq.c
> +++ b/block/blk-mq.c
> @@ -1434,7 +1434,8 @@ static blk_qc_t request_to_qc_t(struct blk_mq_hw_ctx *hctx, struct request *rq)
> return blk_tag_to_qc_t(rq->internal_tag, hctx->queue_num, true);
> }
>
> -static void blk_mq_try_issue_directly(struct request *rq, blk_qc_t *cookie)
> +static void blk_mq_try_issue_directly(struct request *rq, blk_qc_t *cookie,
> + bool can_block)
> {
> struct request_queue *q = rq->q;
> struct blk_mq_queue_data bd = {
> @@ -1475,7 +1476,7 @@ static void blk_mq_try_issue_directly(struct request *rq, blk_qc_t *cookie)
> }
>
> insert:
> - blk_mq_sched_insert_request(rq, false, true, true, false);
> + blk_mq_sched_insert_request(rq, false, true, false, can_block);
> }
>
> /*
> @@ -1569,11 +1570,11 @@ static blk_qc_t blk_mq_make_request(struct request_queue *q, struct bio *bio)
>
> if (!(data.hctx->flags & BLK_MQ_F_BLOCKING)) {
> rcu_read_lock();
> - blk_mq_try_issue_directly(old_rq, &cookie);
> + blk_mq_try_issue_directly(old_rq, &cookie, false);
> rcu_read_unlock();
> } else {
> srcu_idx = srcu_read_lock(&data.hctx->queue_rq_srcu);
> - blk_mq_try_issue_directly(old_rq, &cookie);
> + blk_mq_try_issue_directly(old_rq, &cookie, true);
> srcu_read_unlock(&data.hctx->queue_rq_srcu, srcu_idx);
> }
> goto done;
>
> --
> Jens Axboe
>
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] blk-mq-sched: don't run the queue async from blk_mq_try_issue_directly()
2017-03-14 17:48 ` Omar Sandoval
@ 2017-03-14 17:51 ` Jens Axboe
0 siblings, 0 replies; 5+ messages in thread
From: Jens Axboe @ 2017-03-14 17:51 UTC (permalink / raw)
To: Omar Sandoval; +Cc: linux-block
On 03/14/2017 11:48 AM, Omar Sandoval wrote:
> On Tue, Mar 14, 2017 at 08:57:50AM -0600, Jens Axboe wrote:
>> If we have scheduling enabled, we jump directly to insert-and-run.
>> That's fine, but we run the queue async and we don't pass in information
>> on whether we can block from this context or not. Fixup both these
>> cases.
>
> Reviewed-by: Omar Sandoval <osandov@fb.com>
>
> Just one question: we call blk_mq_get_driver_tag() with wait=false in
> blk_mq_try_issue_directly(). Should we change that to wait=can_block?
> Maybe it's pointless to try a direct issue if we'd have to wait for a
> tag anyways, though.
Exactly, don't want to wait for a tag, at that point we are just
pointlessly stalling an app that could perhaps be submitting more IO.
So I don't think we should factor that in here, better to let the
blocking vs non-blocking drivers behave the same in that regard.
--
Jens Axboe
^ permalink raw reply [flat|nested] 5+ messages in thread
end of thread, other threads:[~2017-03-14 17:51 UTC | newest]
Thread overview: 5+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2017-03-14 14:57 [PATCH] blk-mq-sched: don't run the queue async from blk_mq_try_issue_directly() Jens Axboe
2017-03-14 15:17 ` Bart Van Assche
2017-03-14 15:26 ` Jens Axboe
2017-03-14 17:48 ` Omar Sandoval
2017-03-14 17:51 ` Jens Axboe
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