diff mbox series

[03/11] blk-rq-qos: inline check for q->rq_qos functions

Message ID 20181115195135.22812-4-axboe@kernel.dk (mailing list archive)
State New, archived
Headers show
Series Various block optimizations | expand

Commit Message

Jens Axboe Nov. 15, 2018, 7:51 p.m. UTC 
Put the short code in the fast path, where we don't have any
functions attached to the queue. This minimizes the impact on
the hot path in the core code.

Cc: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
---
 block/blk-rq-qos.c | 63 +++++++++++++++++++++-------------------------
 block/blk-rq-qos.h | 59 +++++++++++++++++++++++++++++++++++++------
 2 files changed, 80 insertions(+), 42 deletions(-)

Comments

Christoph Hellwig Nov. 16, 2018, 8:38 a.m. UTC | #1 
On Thu, Nov 15, 2018 at 12:51:27PM -0700, Jens Axboe wrote:
> Put the short code in the fast path, where we don't have any
> functions attached to the queue. This minimizes the impact on
> the hot path in the core code.

This looks mechanically fine:

Reviewed-by: Christoph Hellwig <hch@lst.de>

But since I seem to have missed the introduction of it - why do we need
multiple struct rq_qos per request to start with?  This sort of stacking
seems rather odd and counter-productive, and the commit introducing
this code doesn't explain the rationale at all.
Jens Axboe Nov. 16, 2018, 3:18 p.m. UTC | #2 
On 11/16/18 1:38 AM, Christoph Hellwig wrote:
> On Thu, Nov 15, 2018 at 12:51:27PM -0700, Jens Axboe wrote:
>> Put the short code in the fast path, where we don't have any
>> functions attached to the queue. This minimizes the impact on
>> the hot path in the core code.
> 
> This looks mechanically fine:
> 
> Reviewed-by: Christoph Hellwig <hch@lst.de>
> 
> But since I seem to have missed the introduction of it - why do we need
> multiple struct rq_qos per request to start with?  This sort of stacking
> seems rather odd and counter-productive, and the commit introducing
> this code doesn't explain the rationale at all.

Per request-queue, not per request. One would be iolatency, one would
be wbt, etc.
diff mbox series

Patch

diff --git a/block/blk-rq-qos.c b/block/blk-rq-qos.c
index f8a4d3fbb98c..80f603b76f61 100644
--- a/block/blk-rq-qos.c
+++ b/block/blk-rq-qos.c
@@ -27,74 +27,67 @@  bool rq_wait_inc_below(struct rq_wait *rq_wait, unsigned int limit)
 	return atomic_inc_below(&rq_wait->inflight, limit);
 }
 
-void rq_qos_cleanup(struct request_queue *q, struct bio *bio)
+void __rq_qos_cleanup(struct rq_qos *rqos, struct bio *bio)
 {
-	struct rq_qos *rqos;
-
-	for (rqos = q->rq_qos; rqos; rqos = rqos->next) {
+	do {
 		if (rqos->ops->cleanup)
 			rqos->ops->cleanup(rqos, bio);
-	}
+		rqos = rqos->next;
+	} while (rqos);
 }
 
-void rq_qos_done(struct request_queue *q, struct request *rq)
+void __rq_qos_done(struct rq_qos *rqos, struct request *rq)
 {
-	struct rq_qos *rqos;
-
-	for (rqos = q->rq_qos; rqos; rqos = rqos->next) {
+	do {
 		if (rqos->ops->done)
 			rqos->ops->done(rqos, rq);
-	}
+		rqos = rqos->next;
+	} while (rqos);
 }
 
-void rq_qos_issue(struct request_queue *q, struct request *rq)
+void __rq_qos_issue(struct rq_qos *rqos, struct request *rq)
 {
-	struct rq_qos *rqos;
-
-	for(rqos = q->rq_qos; rqos; rqos = rqos->next) {
+	do {
 		if (rqos->ops->issue)
 			rqos->ops->issue(rqos, rq);
-	}
+		rqos = rqos->next;
+	} while (rqos);
 }
 
-void rq_qos_requeue(struct request_queue *q, struct request *rq)
+void __rq_qos_requeue(struct rq_qos *rqos, struct request *rq)
 {
-	struct rq_qos *rqos;
-
-	for(rqos = q->rq_qos; rqos; rqos = rqos->next) {
+	do {
 		if (rqos->ops->requeue)
 			rqos->ops->requeue(rqos, rq);
-	}
+		rqos = rqos->next;
+	} while (rqos);
 }
 
-void rq_qos_throttle(struct request_queue *q, struct bio *bio)
+void __rq_qos_throttle(struct rq_qos *rqos, struct bio *bio)
 {
-	struct rq_qos *rqos;
-
-	for(rqos = q->rq_qos; rqos; rqos = rqos->next) {
+	do {
 		if (rqos->ops->throttle)
 			rqos->ops->throttle(rqos, bio);
-	}
+		rqos = rqos->next;
+	} while (rqos);
 }
 
-void rq_qos_track(struct request_queue *q, struct request *rq, struct bio *bio)
+void __rq_qos_track(struct rq_qos *rqos, struct request *rq, struct bio *bio)
 {
-	struct rq_qos *rqos;
-
-	for(rqos = q->rq_qos; rqos; rqos = rqos->next) {
+	do {
 		if (rqos->ops->track)
 			rqos->ops->track(rqos, rq, bio);
-	}
+		rqos = rqos->next;
+	} while (rqos);
 }
 
-void rq_qos_done_bio(struct request_queue *q, struct bio *bio)
+void __rq_qos_done_bio(struct rq_qos *rqos, struct bio *bio)
 {
-	struct rq_qos *rqos;
-
-	for(rqos = q->rq_qos; rqos; rqos = rqos->next) {
+	do {
 		if (rqos->ops->done_bio)
 			rqos->ops->done_bio(rqos, bio);
-	}
+		rqos = rqos->next;
+	} while (rqos);
 }
 
 /*
diff --git a/block/blk-rq-qos.h b/block/blk-rq-qos.h
index b6b11d496007..6e09e98b93ea 100644
--- a/block/blk-rq-qos.h
+++ b/block/blk-rq-qos.h
@@ -98,12 +98,57 @@  void rq_depth_scale_up(struct rq_depth *rqd);
 void rq_depth_scale_down(struct rq_depth *rqd, bool hard_throttle);
 bool rq_depth_calc_max_depth(struct rq_depth *rqd);
 
-void rq_qos_cleanup(struct request_queue *, struct bio *);
-void rq_qos_done(struct request_queue *, struct request *);
-void rq_qos_issue(struct request_queue *, struct request *);
-void rq_qos_requeue(struct request_queue *, struct request *);
-void rq_qos_done_bio(struct request_queue *q, struct bio *bio);
-void rq_qos_throttle(struct request_queue *, struct bio *);
-void rq_qos_track(struct request_queue *q, struct request *, struct bio *);
+void __rq_qos_cleanup(struct rq_qos *rqos, struct bio *bio);
+void __rq_qos_done(struct rq_qos *rqos, struct request *rq);
+void __rq_qos_issue(struct rq_qos *rqos, struct request *rq);
+void __rq_qos_requeue(struct rq_qos *rqos, struct request *rq);
+void __rq_qos_throttle(struct rq_qos *rqos, struct bio *bio);
+void __rq_qos_track(struct rq_qos *rqos, struct request *rq, struct bio *bio);
+void __rq_qos_done_bio(struct rq_qos *rqos, struct bio *bio);
+
+static inline void rq_qos_cleanup(struct request_queue *q, struct bio *bio)
+{
+	if (q->rq_qos)
+		__rq_qos_cleanup(q->rq_qos, bio);
+}
+
+static inline void rq_qos_done(struct request_queue *q, struct request *rq)
+{
+	if (q->rq_qos)
+		__rq_qos_done(q->rq_qos, rq);
+}
+
+static inline void rq_qos_issue(struct request_queue *q, struct request *rq)
+{
+	if (q->rq_qos)
+		__rq_qos_issue(q->rq_qos, rq);
+}
+
+static inline void rq_qos_requeue(struct request_queue *q, struct request *rq)
+{
+	if (q->rq_qos)
+		__rq_qos_requeue(q->rq_qos, rq);
+}
+
+static inline void rq_qos_done_bio(struct request_queue *q, struct bio *bio)
+{
+	if (q->rq_qos)
+		__rq_qos_done_bio(q->rq_qos, bio);
+}
+
+static inline void rq_qos_throttle(struct request_queue *q, struct bio *bio)
+{
+	if (q->rq_qos)
+		__rq_qos_throttle(q->rq_qos, bio);
+}
+
+static inline void rq_qos_track(struct request_queue *q, struct request *rq,
+				struct bio *bio)
+{
+	if (q->rq_qos)
+		__rq_qos_track(q->rq_qos, rq, bio);
+}
+
 void rq_qos_exit(struct request_queue *);
+
 #endif