Re: [PATCH v3 5/5] block: use largest_zero_folio in __blkdev_issue_zero_pages()
From: Pankaj Raghav <hidden>
Date: 2025-08-11 09:35:47
Also in:
linux-fsdevel, linux-mm, lkml
On 8/11/25 10:41, Pankaj Raghav (Samsung) wrote:
From: Pankaj Raghav <redacted> Use largest_zero_folio() in __blkdev_issue_zero_pages(). On systems with CONFIG_PERSISTENT_HUGE_ZERO_FOLIO enabled, we will end up sending larger bvecs instead of multiple small ones. Noticed a 4% increase in performance on a commercial NVMe SSD which does not support OP_WRITE_ZEROES. The device's MDTS was 128K. The performance gains might be bigger if the device supports bigger MDTS. Acked-by: Lorenzo Stoakes <redacted> Signed-off-by: Pankaj Raghav <redacted> --- block/blk-lib.c | 15 ++++++++------- 1 file changed, 8 insertions(+), 7 deletions(-)
@Jens and @Christoph, is it possible to take a quick look of this patch when you have the time? I already made the changes that Christoph mentioned before, so I think it should be good to go. @Christoph, I will send the follow up patches to iomap direct io code once we get these changes merged.
quoted hunk ↗ jump to hunk
diff --git a/block/blk-lib.c b/block/blk-lib.c index 4c9f20a689f7..3030a772d3aa 100644 --- a/block/blk-lib.c +++ b/block/blk-lib.c@@ -196,6 +196,8 @@ static void __blkdev_issue_zero_pages(struct block_device *bdev, sector_t sector, sector_t nr_sects, gfp_t gfp_mask, struct bio **biop, unsigned int flags) { + struct folio *zero_folio = largest_zero_folio(); + while (nr_sects) { unsigned int nr_vecs = __blkdev_sectors_to_bio_pages(nr_sects); struct bio *bio;@@ -208,15 +210,14 @@ static void __blkdev_issue_zero_pages(struct block_device *bdev, break; do { - unsigned int len, added; + unsigned int len; - len = min_t(sector_t, - PAGE_SIZE, nr_sects << SECTOR_SHIFT); - added = bio_add_page(bio, ZERO_PAGE(0), len, 0); - if (added < len) + len = min_t(sector_t, folio_size(zero_folio), + nr_sects << SECTOR_SHIFT); + if (!bio_add_folio(bio, zero_folio, len, 0)) break; - nr_sects -= added >> SECTOR_SHIFT; - sector += added >> SECTOR_SHIFT; + nr_sects -= len >> SECTOR_SHIFT; + sector += len >> SECTOR_SHIFT; } while (nr_sects); *biop = bio_chain_and_submit(*biop, bio);
-- Pankaj