block: add split_alignment for request queue

Message ID	20200616005633.172804-1-harshadshirwadkar@gmail.com (mailing list archive)
State	New, archived
Headers	show Return-Path: <SRS0=kfbW=75=vger.kernel.org=linux-block-owner@kernel.org> From: Harshad Shirwadkar <harshadshirwadkar@gmail.com> To: linux-block@vger.kernel.org Cc: tytso@mit.edu, Harshad Shirwadkar <harshadshirwadkar@gmail.com> Subject: [PATCH] block: add split_alignment for request queue Date: Mon, 15 Jun 2020 17:56:33 -0700 Message-Id: <20200616005633.172804-1-harshadshirwadkar@gmail.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-block-owner@vger.kernel.org Precedence: bulk
Series	block: add split_alignment for request queue \| expand block: add split_alignment for request queue

diff --git a/Documentation/block/queue-sysfs.rst b/Documentation/block/queue-sysfs.rst index 6a8513af9201..c3eaba149415 100644 --- a/Documentation/block/queue-sysfs.rst +++ b/Documentation/block/queue-sysfs.rst @@ -251,4 +251,12 @@ devices are described in the ZBC (Zoned Block Commands) and ZAC do not support zone commands, they will be treated as regular block devices and zoned will report "none". +split_alignment (RW) +---------------------- +This is the alignment in bytes at which the requeust queue is allowed +to split IO requests. Once this value is set, the requeust queue +splits IOs such that the individual IOs are aligned to +split_alignment. The value of 0 indicates that an IO request can be +split anywhere. This value must be a power of 2. + Jens Axboe <jens.axboe@oracle.com>, February 2009 diff --git a/block/blk-merge.c b/block/blk-merge.c index 1534ed736363..cdf337c74b83 100644 --- a/block/blk-merge.c +++ b/block/blk-merge.c @@ -105,15 +105,18 @@ static struct bio *blk_bio_discard_split(struct request_queue *q, static struct bio *blk_bio_write_zeroes_split(struct request_queue *q, struct bio *bio, struct bio_set *bs, unsigned *nsegs) { + sector_t split; + *nsegs = 0; - if (!q->limits.max_write_zeroes_sectors) - return NULL; + split = q->limits.max_write_zeroes_sectors; + if (split && q->split_alignment >> 9) + split = round_down(split, q->split_alignment >> 9); - if (bio_sectors(bio) <= q->limits.max_write_zeroes_sectors) + if (!split || bio_sectors(bio) <= split) return NULL; - return bio_split(bio, q->limits.max_write_zeroes_sectors, GFP_NOIO, bs); + return bio_split(bio, split, GFP_NOIO, bs); } static struct bio *blk_bio_write_same_split(struct request_queue *q, @@ -121,15 +124,18 @@ static struct bio *blk_bio_write_same_split(struct request_queue *q, struct bio_set *bs, unsigned *nsegs) { + sector_t split; + *nsegs = 1; - if (!q->limits.max_write_same_sectors) - return NULL; + split = q->limits.max_write_same_sectors; + if (split && q->split_alignment >> 9) + split = round_down(split, q->split_alignment >> 9); - if (bio_sectors(bio) <= q->limits.max_write_same_sectors) + if (!split || bio_sectors(bio) <= split) return NULL; - return bio_split(bio, q->limits.max_write_same_sectors, GFP_NOIO, bs); + return bio_split(bio, split, GFP_NOIO, bs); } /* @@ -248,7 +254,10 @@ static struct bio *blk_bio_segment_split(struct request_queue *q, { struct bio_vec bv, bvprv, *bvprvp = NULL; struct bvec_iter iter; - unsigned nsegs = 0, sectors = 0; + unsigned int nsegs = 0, nsegs_aligned = 0; + unsigned int sectors = 0, sectors_aligned = 0, before = 0, after = 0; + unsigned int sector_alignment = + q->split_alignment ? (q->split_alignment >> 9) : 0; const unsigned max_sectors = get_max_io_size(q, bio); const unsigned max_segs = queue_max_segments(q); @@ -264,12 +273,31 @@ static struct bio *blk_bio_segment_split(struct request_queue *q, sectors + (bv.bv_len >> 9) <= max_sectors && bv.bv_offset + bv.bv_len <= PAGE_SIZE) { nsegs++; - sectors += bv.bv_len >> 9; - } else if (bvec_split_segs(q, &bv, &nsegs, &sectors, max_segs, - max_sectors)) { - goto split; + before = round_down(sectors, sector_alignment); + sectors += (bv.bv_len >> 9); + after = round_down(sectors, sector_alignment); + if (sector_alignment && before != after) { + /* This is a valid split point */ + nsegs_aligned = nsegs; + sectors_aligned = after; + } + goto next; } - + if (sector_alignment) { + before = round_down(sectors, sector_alignment); + after = round_down(sectors + (bv.bv_len >> 9), + sector_alignment); + if ((nsegs < max_segs) && before != after && + ((after - before) << 9) + bv.bv_offset <= PAGE_SIZE + && after <= max_sectors) { + sectors_aligned = after; + nsegs_aligned = nsegs + 1; + } + } + if (bvec_split_segs(q, &bv, &nsegs, &sectors, max_segs, + max_sectors)) + goto split; +next: bvprv = bv; bvprvp = &bvprv; } @@ -278,7 +306,13 @@ static struct bio *blk_bio_segment_split(struct request_queue *q, return NULL; split: *segs = nsegs; - return bio_split(bio, sectors, GFP_NOIO, bs); + if (sector_alignment && sectors_aligned == 0) + return NULL; + + *segs = sector_alignment ? nsegs_aligned : nsegs; + + return bio_split(bio, sector_alignment ? sectors_aligned : sectors, + GFP_NOIO, bs); } /** diff --git a/block/blk-sysfs.c b/block/blk-sysfs.c index fca9b158f4a0..f045c7a79a74 100644 --- a/block/blk-sysfs.c +++ b/block/blk-sysfs.c @@ -529,6 +529,29 @@ static ssize_t queue_dax_show(struct request_queue *q, char *page) return queue_var_show(blk_queue_dax(q), page); } +static ssize_t queue_split_alignment_show(struct request_queue *q, char *page) +{ + return queue_var_show(q->split_alignment, page); +} + +static ssize_t queue_split_alignment_store(struct request_queue *q, const char *page, + size_t count) +{ + unsigned long split_alignment; + int ret; + + ret = queue_var_store(&split_alignment, page, count); + if (ret < 0) + return ret; + + /* split_alignment can only be a power of 2 */ + if (split_alignment & (split_alignment - 1)) + return -EINVAL; + + q->split_alignment = split_alignment; + return count; +} + static struct queue_sysfs_entry queue_requests_entry = { .attr = {.name = "nr_requests", .mode = 0644 }, .show = queue_requests_show, @@ -727,6 +750,12 @@ static struct queue_sysfs_entry throtl_sample_time_entry = { }; #endif +static struct queue_sysfs_entry queue_split_alignment = { + .attr = {.name = "split_alignment", .mode = 0644 }, + .show = queue_split_alignment_show, + .store = queue_split_alignment_store, +}; + static struct attribute *queue_attrs[] = { &queue_requests_entry.attr, &queue_ra_entry.attr, @@ -766,6 +795,7 @@ static struct attribute *queue_attrs[] = { #ifdef CONFIG_BLK_DEV_THROTTLING_LOW &throtl_sample_time_entry.attr, #endif + &queue_split_alignment.attr, NULL, }; diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h index 32868fbedc9e..e8feb43f6fdd 100644 --- a/include/linux/blkdev.h +++ b/include/linux/blkdev.h @@ -473,6 +473,7 @@ struct request_queue { void *dma_drain_buffer; unsigned int dma_pad_mask; unsigned int dma_alignment; + unsigned int split_alignment; unsigned int rq_timeout; int poll_nsec;

block: add split_alignment for request queue

Commit Message

Comments

Patch