diff mbox series

[RESEND,v3,03/13] blk-mq: Relocate shared sbitmap resize in blk_mq_update_nr_requests()

Message ID 1631545950-56586-4-git-send-email-john.garry@huawei.com
State New
Headers show
Series blk-mq: Reduce static requests memory footprint for shared sbitmap | expand

Commit Message

John Garry Sept. 13, 2021, 3:12 p.m. UTC 
For shared sbitmap, if the call to blk_mq_tag_update_depth() was
successful for any hctx when hctx->sched_tags is not set, then it would be
successful for all (due to nature in which blk_mq_tag_update_depth()
fails).

As such, there is no need to call blk_mq_tag_resize_shared_sbitmap() for
each hctx. So relocate the call until after the hctx iteration under the
!q->elevator check, which is equivalent (to !hctx->sched_tags).

Signed-off-by: John Garry <john.garry@huawei.com>

Reviewed-by: Ming Lei <ming.lei@redhat.com>

---
 block/blk-mq.c | 12 +++++++-----
 1 file changed, 7 insertions(+), 5 deletions(-)

-- 
2.26.2

Comments

Hannes Reinecke Sept. 14, 2021, 5:37 a.m. UTC | #1 
On 9/13/21 5:12 PM, John Garry wrote:
> For shared sbitmap, if the call to blk_mq_tag_update_depth() was

> successful for any hctx when hctx->sched_tags is not set, then it would be

> successful for all (due to nature in which blk_mq_tag_update_depth()

> fails).

> 

> As such, there is no need to call blk_mq_tag_resize_shared_sbitmap() for

> each hctx. So relocate the call until after the hctx iteration under the

> !q->elevator check, which is equivalent (to !hctx->sched_tags).

> 

> Signed-off-by: John Garry <john.garry@huawei.com>

> Reviewed-by: Ming Lei <ming.lei@redhat.com>

> ---

>   block/blk-mq.c | 12 +++++++-----

>   1 file changed, 7 insertions(+), 5 deletions(-)

> 

Reviewed-by: Hannes Reinecke <hare@suse.de>


Cheers,

Hannes
-- 
Dr. Hannes Reinecke                Kernel Storage Architect
hare@suse.de                              +49 911 74053 688
SUSE Software Solutions GmbH, Maxfeldstr. 5, 90409 Nürnberg
HRB 36809 (AG Nürnberg), Geschäftsführer: Felix Imendörffer
diff mbox series

Patch

diff --git a/block/blk-mq.c b/block/blk-mq.c
index 2316ff27c1f5..1a4bb2db30e5 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -3616,8 +3616,6 @@  int blk_mq_update_nr_requests(struct request_queue *q, unsigned int nr)
 		if (!hctx->sched_tags) {
 			ret = blk_mq_tag_update_depth(hctx, &hctx->tags, nr,
 							false);
-			if (!ret && blk_mq_is_sbitmap_shared(set->flags))
-				blk_mq_tag_resize_shared_sbitmap(set, nr);
 		} else {
 			ret = blk_mq_tag_update_depth(hctx, &hctx->sched_tags,
 							nr, true);
@@ -3635,9 +3633,13 @@  int blk_mq_update_nr_requests(struct request_queue *q, unsigned int nr)
 	}
 	if (!ret) {
 		q->nr_requests = nr;
-		if (q->elevator && blk_mq_is_sbitmap_shared(set->flags))
-			sbitmap_queue_resize(&q->sched_bitmap_tags,
-					     nr - set->reserved_tags);
+		if (blk_mq_is_sbitmap_shared(set->flags)) {
+			if (q->elevator)
+				sbitmap_queue_resize(&q->sched_bitmap_tags,
+						     nr - set->reserved_tags);
+			else
+				blk_mq_tag_resize_shared_sbitmap(set, nr);
+		}
 	}
 
 	blk_mq_unquiesce_queue(q);