On Thu, Mar 12, 2020 at 07:13:28PM +0800, Feng Li wrote:
> Hi experts,
>
> May I ask a question about block layer?
> When running fio in guest os, I find a 256k IO is split into the page
> by page in bio, saved in bvecs.
> And virtio-blk just put the bio_vec one by one in the available
> descriptor table.
>
> So if my backend device does not support iovector
> opertion(preadv/pwritev), then IO is issued to a low layer page by
> page.
> My question is: why doesn't the bio save multi-pages in one bio_vec?
We start multipage bvec since v5.1, especially since 07173c3ec276
("block: enable multipage bvecs").
Thanks,
Ming
