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From: Pankaj Raghav
To: Suren Baghdasaryan ,
Ryan Roberts ,
Mike Rapoport ,
Michal Hocko ,
Thomas Gleixner ,
Nico Pache ,
Dev Jain ,
Baolin Wang ,
Borislav Petkov ,
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Cc: linux-kernel@vger.kernel.org,
linux-mm@kvack.org,
willy@infradead.org,
x86@kernel.org,
linux-block@vger.kernel.org,
linux-fsdevel@vger.kernel.org,
"Darrick J . Wong" ,
mcgrof@kernel.org,
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hch@lst.de,
Pankaj Raghav
Subject: [PATCH 5/5] block: use mm_huge_zero_folio in
__blkdev_issue_zero_pages()
Date: Thu, 12 Jun 2025 12:51:00 +0200
Message-ID: <20250612105100.59144-6-p.raghav@samsung.com>
In-Reply-To: <20250612105100.59144-1-p.raghav@samsung.com>
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Use mm_get_static_huge_zero_folio() in __blkdev_issue_zero_pages().
On systems with CONFIG_STATIC_PMD_ZERO_PAGE 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.
Signed-off-by: Pankaj Raghav
---
block/blk-lib.c | 17 ++++++++++-------
1 file changed, 10 insertions(+), 7 deletions(-)
diff --git a/block/blk-lib.c b/block/blk-lib.c
index 4c9f20a689f7..4ee219637a3f 100644
--- a/block/blk-lib.c
+++ b/block/blk-lib.c
@@ -196,6 +196,10 @@ static void __blkdev_issue_zero_pages(struct block_dev=
ice *bdev,
sector_t sector, sector_t nr_sects, gfp_t gfp_mask,
struct bio **biop, unsigned int flags)
{
+ struct folio *zero_folio;
+
+ zero_folio =3D mm_get_static_huge_zero_folio();
+
while (nr_sects) {
unsigned int nr_vecs =3D __blkdev_sectors_to_bio_pages(nr_sects);
struct bio *bio;
@@ -208,15 +212,14 @@ static void __blkdev_issue_zero_pages(struct block_de=
vice *bdev,
break;
=20
do {
- unsigned int len, added;
+ unsigned int len;
=20
- len =3D min_t(sector_t,
- PAGE_SIZE, nr_sects << SECTOR_SHIFT);
- added =3D bio_add_page(bio, ZERO_PAGE(0), len, 0);
- if (added < len)
+ len =3D min_t(sector_t, folio_size(zero_folio),
+ nr_sects << SECTOR_SHIFT);
+ if (!bio_add_folio(bio, zero_folio, len, 0))
break;
- nr_sects -=3D added >> SECTOR_SHIFT;
- sector +=3D added >> SECTOR_SHIFT;
+ nr_sects -=3D len >> SECTOR_SHIFT;
+ sector +=3D len >> SECTOR_SHIFT;
} while (nr_sects);
=20
*biop =3D bio_chain_and_submit(*biop, bio);
--=20
2.49.0