On 8/11/25 10:41, Pankaj Raghav (Samsung) wrote:
> From: Pankaj Raghav <p.raghav@xxxxxxxxxxx>
>
> 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 <lorenzo.stoakes@xxxxxxxxxx>
> Signed-off-by: Pankaj Raghav <p.raghav@xxxxxxxxxxx>
> ---
> 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.
> 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
