[GEDI] [PATCH v5 11/12] blkio: implement BDRV_REQ_REGISTERED_BUF optimization

[Alberto Faria]

On Thu, Oct 6, 2022 at 7:46 PM Stefan Hajnoczi <stefanha at redhat.com> wrote:
> > Regardless, I'd say we want to map memory regions even if we don't
> > strictly need to (in cases where we can do so at no additional cost),
> > since that may improve performance for some drivers.
>
> The downside is that when s->mem_regions_pinned is true, virtio-mem and
> anything else that calls ram discard cannot be used.

Hmm right, losing that functionality would probably be worse than
potentially losing some performance for some drivers. Maybe a good
middle point would be to call blkio_map_mem_region() in
blkio_register_buf() iff s->needs_mem_regions ||
!s->mem_regions_pinned.

Alberto