On Thu, Apr 15, 2021 at 04:33:27PM +0800, Yongji Xie wrote:
> On Thu, Apr 15, 2021 at 3:19 PM Stefan Hajnoczi <stefanha@redhat.com> wrote:
> > On Thu, Apr 15, 2021 at 01:38:37PM +0800, Yongji Xie wrote:
> > > On Wed, Apr 14, 2021 at 10:15 PM Stefan Hajnoczi <stefanha@redhat.com> wrote:
> > > > On Wed, Mar 31, 2021 at 04:05:19PM +0800, Xie Yongji wrote:
> > It's not obvious to me that there is a fundamental difference between
> > the two approaches in terms of performance.
> >
> > > On the other
> > > hand, we can handle the virtqueue in a unified way for both vhost-vdpa
> > > case and virtio-vdpa case. Otherwise, userspace daemon needs to know
> > > which iova ranges need to be accessed with pread(2)/pwrite(2). And in
> > > the future, we might be able to avoid bouncing in some cases.
> >
> > Ah, I see. So bounce buffers are not used for vhost-vdpa?
> >
> 
> Yes.

Okay, in that case I understand why mmap is used and it's nice to keep
virtio-vpda and vhost-vdpa unified. Thanks!

Stefan