On Mon, Mar 14, 2022 at 8:33 PM Suwan Kim <suwan.kim027@gmail.com> wrote:

> On Mon, Mar 14, 2022 at 02:14:53PM +0800, Jason Wang wrote:
> >
> > 在 2022/3/11 下午11:28, Suwan Kim 写道:
> > > diff --git a/include/uapi/linux/virtio_blk.h
> b/include/uapi/linux/virtio_blk.h
> > > index d888f013d9ff..3fcaf937afe1 100644
> > > --- a/include/uapi/linux/virtio_blk.h
> > > +++ b/include/uapi/linux/virtio_blk.h
> > > @@ -119,8 +119,9 @@ struct virtio_blk_config {
> > >      * deallocation of one or more of the sectors.
> > >      */
> > >     __u8 write_zeroes_may_unmap;
> > > +   __u8 unused1;
> > > -   __u8 unused1[3];
> > > +   __virtio16 num_poll_queues;
> > >   } __attribute__((packed));
> >
> >
> > This looks like a implementation specific (virtio-blk-pci) optimization,
> how
> > about other implementation like vhost-user-blk?
>
> I didn’t consider vhost-user-blk yet. But does vhost-user-blk also
> use vritio_blk_config as kernel-qemu interface?
>

Yes, but see below.


>
> Does vhost-user-blk need additional modification to support polling
> in kernel side?
>


No, but the issue is, things like polling looks not a good candidate for
the attributes belonging to the device but the driver. So I have more
questions:

1) what does it really mean for hardware virtio block devices?
2) Does driver polling help for the qemu implementation without polling?
3) Using blk_config means we can only get the benefit from the new device

Thanks



> Regards,
> Suwan Kim
>
>