Re: [RFC 3/3] block: use mm_huge_zero_folio in __blkdev_issue_zero_pages()

[Christoph Hellwig]

On Tue, May 27, 2025 at 07:04:52AM +0200, Pankaj Raghav wrote:
> 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.

Impressive gain on the one hand - on the other hand what is the macro
workload that does a lot of zeroing on an SSD, because avoiding that
should yield even better result while reducing wear..

> +			unsigned int len, added = 0;
>  
> +			len = min_t(sector_t, folio_size(zero_folio),
> +				    nr_sects << SECTOR_SHIFT);
> +			if (bio_add_folio(bio, zero_folio, len, 0))
> +				added = len;
>  			if (added < len)
>  				break;
>  			nr_sects -= added >> SECTOR_SHIFT;

Unless I'm missing something the added variable can go away now, and
the code using it can simply use len.