| Message ID | 1626275195-215652-4-git-send-email-john.garry@huawei.com |
|---|---|
| State | New |
| Headers | show |
| Series | blk-mq: Reduce static requests memory footprint for shared sbitmap | expand |
On Wed, Jul 14, 2021 at 11:06:29PM +0800, 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> > --- > block/blk-mq.c | 13 ++++++++----- > 1 file changed, 8 insertions(+), 5 deletions(-) > > diff --git a/block/blk-mq.c b/block/blk-mq.c > index ae28f470893c..56e3c6fdba60 100644 > --- a/block/blk-mq.c > +++ b/block/blk-mq.c > @@ -3624,8 +3624,6 @@ 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); > @@ -3643,9 +3641,14 @@ 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); > + } The above two {} can be removed. -- Ming
On 20/07/2021 08:50, Ming Lei wrote: >> Signed-off-by: John Garry<john.garry@huawei.com> >> --- >> block/blk-mq.c | 13 ++++++++----- >> 1 file changed, 8 insertions(+), 5 deletions(-) >> >> diff --git a/block/blk-mq.c b/block/blk-mq.c >> index ae28f470893c..56e3c6fdba60 100644 >> --- a/block/blk-mq.c >> +++ b/block/blk-mq.c >> @@ -3624,8 +3624,6 @@ 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); >> @@ -3643,9 +3641,14 @@ 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)) { Hi Ming, >> + if (q->elevator) { >> + sbitmap_queue_resize(&q->sched_bitmap_tags, >> + nr - set->reserved_tags); I have learned that some people prefer {} for multi-line single statements, like this. Anyway, more code is added here later in the series, so better to add {} now, rather than re-arrange code later. >> + } else { >> + blk_mq_tag_resize_shared_sbitmap(set, nr); >> + } > The above two {} can be removed. Thanks, John
diff --git a/block/blk-mq.c b/block/blk-mq.c index ae28f470893c..56e3c6fdba60 100644 --- a/block/blk-mq.c +++ b/block/blk-mq.c @@ -3624,8 +3624,6 @@ 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); @@ -3643,9 +3641,14 @@ 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);
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> --- block/blk-mq.c | 13 ++++++++----- 1 file changed, 8 insertions(+), 5 deletions(-) -- 2.26.2