Re: [virtio-dev] Re: [PATCH v2 4/5] virtio-mmio: add MSI interrupt feature support

[Jason Wang]

On 2020/2/12 äå5:16, Michael S. Tsirkin wrote:
> > > Thanks for the advice.:)
> > >
> > > Actually when looking into pci, the queue_msix_vector/msix_config is the
> > > msi vector index, which is the same as the mmio register MsiVecSel
> > > (0x0d0).
> > >
> > > So we don't introduce two extra registers for mapping even in sharing
> > > mode.
> > >
> > > What do you think?
> > I'm not sure I get the point, but I still prefer the separate vector_sel
> > from queue_msix_vector.
> >
> > Btw, Michael propose per vq registers which could also work.
> >
> > Thanks
> Right and I'd even ask a question: do we need shared MSI at all?


I guess it is still needed at least for the current virtio code. 
Technically we may have thousands queues.

Thanks


> Is it somehow better than legacy interrupt? And why?
> Performance numbers please.