| Message ID | 20210204010156.5105-1-nanich.lee@samsung.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [v5,1/2] bio: limit bio max size | expand |
Please feedback to me if more modification is needed to apply. :) --- Changheun Lee
On Tue, Feb 16, 2021 at 11:00:32AM +0900, Changheun Lee wrote:
> Please feedback to me if more modification is needed to apply. :)
No context here :(
> > On Tue, Feb 16, 2021 at 11:00:32AM +0900, Changheun Lee wrote: > > Please feedback to me if more modification is needed to apply. :) > > No context here :( > I'm so sorry. I missed it. > bio size can grow up to 4GB when muli-page bvec is enabled. > but sometimes it would lead to inefficient behaviors. > in case of large chunk direct I/O, - 32MB chunk read in user space - > all pages for 32MB would be merged to a bio structure if the pages > physical addresses are contiguous. it makes some delay to submit > until merge complete. bio max size should be limited to a proper size. > > When 32MB chunk read with direct I/O option is coming from userspace, > kernel behavior is below now in do_direct_IO() loop. it's timeline. > > | bio merge for 32MB. total 8,192 pages are merged. > | total elapsed time is over 2ms. > |------------------ ... ----------------------->| > | 8,192 pages merged a bio. > | at this time, first bio submit is done. > | 1 bio is split to 32 read request and issue. > |---------------> > |---------------> > |---------------> > ...... > |---------------> > |--------------->| > total 19ms elapsed to complete 32MB read done from device. | > > If bio max size is limited with 1MB, behavior is changed below. > > | bio merge for 1MB. 256 pages are merged for each bio. > | total 32 bio will be made. > | total elapsed time is over 2ms. it's same. > | but, first bio submit timing is fast. about 100us. > |--->|--->|--->|---> ... -->|--->|--->|--->|--->| > | 256 pages merged a bio. > | at this time, first bio submit is done. > | and 1 read request is issued for 1 bio. > |---------------> > |---------------> > |---------------> > ...... > |---------------> > |--------------->| > total 17ms elapsed to complete 32MB read done from device. | > > As a result, read request issue timing is faster if bio max size is limited. > Current kernel behavior with multipage bvec, super large bio can be created. > And it lead to delay first I/O request issue. > > Signed-off-by: Changheun Lee <nanich.lee@samsung.com> > --- > block/bio.c | 13 ++++++++++++- > include/linux/bio.h | 2 +- > include/linux/blkdev.h | 3 +++ > 3 files changed, 16 insertions(+), 2 deletions(-) > > diff --git a/block/bio.c b/block/bio.c > index 1f2cc1fbe283..c528e1f944c7 100644 > --- a/block/bio.c > +++ b/block/bio.c > @@ -287,6 +287,17 @@ void bio_init(struct bio *bio, struct bio_vec *table, > } > EXPORT_SYMBOL(bio_init); > > +unsigned int bio_max_size(struct bio *bio) > +{ > + struct request_queue *q = bio->bi_disk->queue; > + > + if (blk_queue_limit_bio_size(q)) > + return blk_queue_get_max_sectors(q, bio_op(bio)) > + << SECTOR_SHIFT; > + > + return UINT_MAX; > +} > + > /** > * bio_reset - reinitialize a bio > * @bio: bio to reset > @@ -877,7 +888,7 @@ bool __bio_try_merge_page(struct bio *bio, struct page *page, > struct bio_vec *bv = &bio->bi_io_vec[bio->bi_vcnt - 1]; > > if (page_is_mergeable(bv, page, len, off, same_page)) { > - if (bio->bi_iter.bi_size > UINT_MAX - len) { > + if (bio->bi_iter.bi_size > bio_max_size(bio) - len) { > *same_page = false; > return false; > } > diff --git a/include/linux/bio.h b/include/linux/bio.h > index 1edda614f7ce..13b6f6562a5b 100644 > --- a/include/linux/bio.h > +++ b/include/linux/bio.h > @@ -113,7 +113,7 @@ static inline bool bio_full(struct bio *bio, unsigned len) > if (bio->bi_vcnt >= bio->bi_max_vecs) > return true; > > - if (bio->bi_iter.bi_size > UINT_MAX - len) > + if (bio->bi_iter.bi_size > bio_max_size(bio) - len) > return true; > > return false; > diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h > index f94ee3089e01..3aeab9e7e97b 100644 > --- a/include/linux/blkdev.h > +++ b/include/linux/blkdev.h > @@ -621,6 +621,7 @@ struct request_queue { > #define QUEUE_FLAG_RQ_ALLOC_TIME 27 /* record rq->alloc_time_ns */ > #define QUEUE_FLAG_HCTX_ACTIVE 28 /* at least one blk-mq hctx is active */ > #define QUEUE_FLAG_NOWAIT 29 /* device supports NOWAIT */ > +#define QUEUE_FLAG_LIMIT_BIO_SIZE 30 /* limit bio size */ > > #define QUEUE_FLAG_MQ_DEFAULT ((1 << QUEUE_FLAG_IO_STAT) | \ > (1 << QUEUE_FLAG_SAME_COMP) | \ > @@ -667,6 +668,8 @@ bool blk_queue_flag_test_and_set(unsigned int flag, struct request_queue *q); > #define blk_queue_fua(q) test_bit(QUEUE_FLAG_FUA, &(q)->queue_flags) > #define blk_queue_registered(q) test_bit(QUEUE_FLAG_REGISTERED, &(q)->queue_flags) > #define blk_queue_nowait(q) test_bit(QUEUE_FLAG_NOWAIT, &(q)->queue_flags) > +#define blk_queue_limit_bio_size(q) \ > + test_bit(QUEUE_FLAG_LIMIT_BIO_SIZE, &(q)->queue_flags) > > extern void blk_set_pm_only(struct request_queue *q); > extern void blk_clear_pm_only(struct request_queue *q); > -- > 2.28.0 > Please feedback to me if more modification is needed to apply. :) --- Changheun Lee
On Tue, Feb 16, 2021 at 03:42:42PM +0900, Changheun Lee wrote: > > > > On Tue, Feb 16, 2021 at 11:00:32AM +0900, Changheun Lee wrote: > > > Please feedback to me if more modification is needed to apply. :) > > > > No context here :( > > > > I'm so sorry. I missed it. > > > bio size can grow up to 4GB when muli-page bvec is enabled. > > but sometimes it would lead to inefficient behaviors. > > in case of large chunk direct I/O, - 32MB chunk read in user space - > > all pages for 32MB would be merged to a bio structure if the pages > > physical addresses are contiguous. it makes some delay to submit > > until merge complete. bio max size should be limited to a proper size. > > > > When 32MB chunk read with direct I/O option is coming from userspace, > > kernel behavior is below now in do_direct_IO() loop. it's timeline. > > > > | bio merge for 32MB. total 8,192 pages are merged. > > | total elapsed time is over 2ms. > > |------------------ ... ----------------------->| > > | 8,192 pages merged a bio. > > | at this time, first bio submit is done. > > | 1 bio is split to 32 read request and issue. > > |---------------> > > |---------------> > > |---------------> > > ...... > > |---------------> > > |--------------->| > > total 19ms elapsed to complete 32MB read done from device. | > > > > If bio max size is limited with 1MB, behavior is changed below. > > > > | bio merge for 1MB. 256 pages are merged for each bio. > > | total 32 bio will be made. > > | total elapsed time is over 2ms. it's same. > > | but, first bio submit timing is fast. about 100us. > > |--->|--->|--->|---> ... -->|--->|--->|--->|--->| > > | 256 pages merged a bio. > > | at this time, first bio submit is done. > > | and 1 read request is issued for 1 bio. > > |---------------> > > |---------------> > > |---------------> > > ...... > > |---------------> > > |--------------->| > > total 17ms elapsed to complete 32MB read done from device. | > > > > As a result, read request issue timing is faster if bio max size is limited. > > Current kernel behavior with multipage bvec, super large bio can be created. > > And it lead to delay first I/O request issue. > > > > Signed-off-by: Changheun Lee <nanich.lee@samsung.com> > > --- > > block/bio.c | 13 ++++++++++++- > > include/linux/bio.h | 2 +- > > include/linux/blkdev.h | 3 +++ > > 3 files changed, 16 insertions(+), 2 deletions(-) > > > > diff --git a/block/bio.c b/block/bio.c > > index 1f2cc1fbe283..c528e1f944c7 100644 > > --- a/block/bio.c > > +++ b/block/bio.c > > @@ -287,6 +287,17 @@ void bio_init(struct bio *bio, struct bio_vec *table, > > } > > EXPORT_SYMBOL(bio_init); > > > > +unsigned int bio_max_size(struct bio *bio) > > +{ > > + struct request_queue *q = bio->bi_disk->queue; > > + > > + if (blk_queue_limit_bio_size(q)) > > + return blk_queue_get_max_sectors(q, bio_op(bio)) > > + << SECTOR_SHIFT; > > + > > + return UINT_MAX; > > +} > > + > > /** > > * bio_reset - reinitialize a bio > > * @bio: bio to reset > > @@ -877,7 +888,7 @@ bool __bio_try_merge_page(struct bio *bio, struct page *page, > > struct bio_vec *bv = &bio->bi_io_vec[bio->bi_vcnt - 1]; > > > > if (page_is_mergeable(bv, page, len, off, same_page)) { > > - if (bio->bi_iter.bi_size > UINT_MAX - len) { > > + if (bio->bi_iter.bi_size > bio_max_size(bio) - len) { > > *same_page = false; > > return false; > > } > > diff --git a/include/linux/bio.h b/include/linux/bio.h > > index 1edda614f7ce..13b6f6562a5b 100644 > > --- a/include/linux/bio.h > > +++ b/include/linux/bio.h > > @@ -113,7 +113,7 @@ static inline bool bio_full(struct bio *bio, unsigned len) > > if (bio->bi_vcnt >= bio->bi_max_vecs) > > return true; > > > > - if (bio->bi_iter.bi_size > UINT_MAX - len) > > + if (bio->bi_iter.bi_size > bio_max_size(bio) - len) > > return true; > > > > return false; > > diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h > > index f94ee3089e01..3aeab9e7e97b 100644 > > --- a/include/linux/blkdev.h > > +++ b/include/linux/blkdev.h > > @@ -621,6 +621,7 @@ struct request_queue { > > #define QUEUE_FLAG_RQ_ALLOC_TIME 27 /* record rq->alloc_time_ns */ > > #define QUEUE_FLAG_HCTX_ACTIVE 28 /* at least one blk-mq hctx is active */ > > #define QUEUE_FLAG_NOWAIT 29 /* device supports NOWAIT */ > > +#define QUEUE_FLAG_LIMIT_BIO_SIZE 30 /* limit bio size */ > > > > #define QUEUE_FLAG_MQ_DEFAULT ((1 << QUEUE_FLAG_IO_STAT) | \ > > (1 << QUEUE_FLAG_SAME_COMP) | \ > > @@ -667,6 +668,8 @@ bool blk_queue_flag_test_and_set(unsigned int flag, struct request_queue *q); > > #define blk_queue_fua(q) test_bit(QUEUE_FLAG_FUA, &(q)->queue_flags) > > #define blk_queue_registered(q) test_bit(QUEUE_FLAG_REGISTERED, &(q)->queue_flags) > > #define blk_queue_nowait(q) test_bit(QUEUE_FLAG_NOWAIT, &(q)->queue_flags) > > +#define blk_queue_limit_bio_size(q) \ > > + test_bit(QUEUE_FLAG_LIMIT_BIO_SIZE, &(q)->queue_flags) > > > > extern void blk_set_pm_only(struct request_queue *q); > > extern void blk_clear_pm_only(struct request_queue *q); > > -- > > 2.28.0 > > > > Please feedback to me if more modification is needed to apply. :) It's the middle of the merge window, no maintainers can add anything new to their trees, so please wait until after 5.12-rc1 is out before we can do anything... thanks, greg k-h
diff --git a/block/bio.c b/block/bio.c index 1f2cc1fbe283..c528e1f944c7 100644 --- a/block/bio.c +++ b/block/bio.c @@ -287,6 +287,17 @@ void bio_init(struct bio *bio, struct bio_vec *table, } EXPORT_SYMBOL(bio_init); +unsigned int bio_max_size(struct bio *bio) +{ + struct request_queue *q = bio->bi_disk->queue; + + if (blk_queue_limit_bio_size(q)) + return blk_queue_get_max_sectors(q, bio_op(bio)) + << SECTOR_SHIFT; + + return UINT_MAX; +} + /** * bio_reset - reinitialize a bio * @bio: bio to reset @@ -877,7 +888,7 @@ bool __bio_try_merge_page(struct bio *bio, struct page *page, struct bio_vec *bv = &bio->bi_io_vec[bio->bi_vcnt - 1]; if (page_is_mergeable(bv, page, len, off, same_page)) { - if (bio->bi_iter.bi_size > UINT_MAX - len) { + if (bio->bi_iter.bi_size > bio_max_size(bio) - len) { *same_page = false; return false; } diff --git a/include/linux/bio.h b/include/linux/bio.h index 1edda614f7ce..13b6f6562a5b 100644 --- a/include/linux/bio.h +++ b/include/linux/bio.h @@ -113,7 +113,7 @@ static inline bool bio_full(struct bio *bio, unsigned len) if (bio->bi_vcnt >= bio->bi_max_vecs) return true; - if (bio->bi_iter.bi_size > UINT_MAX - len) + if (bio->bi_iter.bi_size > bio_max_size(bio) - len) return true; return false; diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h index f94ee3089e01..3aeab9e7e97b 100644 --- a/include/linux/blkdev.h +++ b/include/linux/blkdev.h @@ -621,6 +621,7 @@ struct request_queue { #define QUEUE_FLAG_RQ_ALLOC_TIME 27 /* record rq->alloc_time_ns */ #define QUEUE_FLAG_HCTX_ACTIVE 28 /* at least one blk-mq hctx is active */ #define QUEUE_FLAG_NOWAIT 29 /* device supports NOWAIT */ +#define QUEUE_FLAG_LIMIT_BIO_SIZE 30 /* limit bio size */ #define QUEUE_FLAG_MQ_DEFAULT ((1 << QUEUE_FLAG_IO_STAT) | \ (1 << QUEUE_FLAG_SAME_COMP) | \ @@ -667,6 +668,8 @@ bool blk_queue_flag_test_and_set(unsigned int flag, struct request_queue *q); #define blk_queue_fua(q) test_bit(QUEUE_FLAG_FUA, &(q)->queue_flags) #define blk_queue_registered(q) test_bit(QUEUE_FLAG_REGISTERED, &(q)->queue_flags) #define blk_queue_nowait(q) test_bit(QUEUE_FLAG_NOWAIT, &(q)->queue_flags) +#define blk_queue_limit_bio_size(q) \ + test_bit(QUEUE_FLAG_LIMIT_BIO_SIZE, &(q)->queue_flags) extern void blk_set_pm_only(struct request_queue *q); extern void blk_clear_pm_only(struct request_queue *q);
bio size can grow up to 4GB when muli-page bvec is enabled. but sometimes it would lead to inefficient behaviors. in case of large chunk direct I/O, - 32MB chunk read in user space - all pages for 32MB would be merged to a bio structure if the pages physical addresses are contiguous. it makes some delay to submit until merge complete. bio max size should be limited to a proper size. When 32MB chunk read with direct I/O option is coming from userspace, kernel behavior is below now in do_direct_IO() loop. it's timeline. | bio merge for 32MB. total 8,192 pages are merged. | total elapsed time is over 2ms. |------------------ ... ----------------------->| | 8,192 pages merged a bio. | at this time, first bio submit is done. | 1 bio is split to 32 read request and issue. |---------------> |---------------> |---------------> ...... |---------------> |--------------->| total 19ms elapsed to complete 32MB read done from device. | If bio max size is limited with 1MB, behavior is changed below. | bio merge for 1MB. 256 pages are merged for each bio. | total 32 bio will be made. | total elapsed time is over 2ms. it's same. | but, first bio submit timing is fast. about 100us. |--->|--->|--->|---> ... -->|--->|--->|--->|--->| | 256 pages merged a bio. | at this time, first bio submit is done. | and 1 read request is issued for 1 bio. |---------------> |---------------> |---------------> ...... |---------------> |--------------->| total 17ms elapsed to complete 32MB read done from device. | As a result, read request issue timing is faster if bio max size is limited. Current kernel behavior with multipage bvec, super large bio can be created. And it lead to delay first I/O request issue. Signed-off-by: Changheun Lee <nanich.lee@samsung.com> --- block/bio.c | 13 ++++++++++++- include/linux/bio.h | 2 +- include/linux/blkdev.h | 3 +++ 3 files changed, 16 insertions(+), 2 deletions(-)