On Tue, Dec 20, 2022 at 6:14 PM Yongji Xie <xieyongji@xxxxxxxxxxxxx> wrote:
>
> On Tue, Dec 20, 2022 at 2:31 PM Jason Wang <jasowang@xxxxxxxxxx> wrote:
> >
> > On Mon, Dec 19, 2022 at 3:12 PM Yongji Xie <xieyongji@xxxxxxxxxxxxx> wrote:
> > >
> > > On Mon, Dec 19, 2022 at 2:06 PM Jason Wang <jasowang@xxxxxxxxxx> wrote:
> > > >
> > > > On Mon, Dec 19, 2022 at 12:39 PM Yongji Xie <xieyongji@xxxxxxxxxxxxx> wrote:
> > > > >
> > > > > On Fri, Dec 16, 2022 at 11:58 AM Jason Wang <jasowang@xxxxxxxxxx> wrote:
> > > > > >
> > > > > > On Mon, Dec 5, 2022 at 4:43 PM Xie Yongji <xieyongji@xxxxxxxxxxxxx> wrote:
> > > > > > >
> > > > > > > This introduces set_irq_affinity callback in
> > > > > > > vdpa_config_ops so that vdpa device driver can
> > > > > > > get the interrupt affinity hint from the virtio
> > > > > > > device driver. The interrupt affinity hint would
> > > > > > > be needed by the interrupt affinity spreading
> > > > > > > mechanism.
> > > > > > >
> > > > > > > Signed-off-by: Xie Yongji <xieyongji@xxxxxxxxxxxxx>
> > > > > > > ---
> > > > > > > drivers/virtio/virtio_vdpa.c | 4 ++++
> > > > > > > include/linux/vdpa.h | 8 ++++++++
> > > > > > > 2 files changed, 12 insertions(+)
> > > > > > >
> > > > > > > diff --git a/drivers/virtio/virtio_vdpa.c b/drivers/virtio/virtio_vdpa.c
> > > > > > > index 08084b49e5a1..4731e4616ee0 100644
> > > > > > > --- a/drivers/virtio/virtio_vdpa.c
> > > > > > > +++ b/drivers/virtio/virtio_vdpa.c
> > > > > > > @@ -275,9 +275,13 @@ static int virtio_vdpa_find_vqs(struct virtio_device *vdev, unsigned int nvqs,
> > > > > > > struct virtio_vdpa_device *vd_dev = to_virtio_vdpa_device(vdev);
> > > > > > > struct vdpa_device *vdpa = vd_get_vdpa(vdev);
> > > > > > > const struct vdpa_config_ops *ops = vdpa->config;
> > > > > > > + struct irq_affinity default_affd = { 0 };
> > > > > > > struct vdpa_callback cb;
> > > > > > > int i, err, queue_idx = 0;
> > > > > > >
> > > > > > > + if (ops->set_irq_affinity)
> > > > > > > + ops->set_irq_affinity(vdpa, desc ? desc : &default_affd);
> > > > > >
> > > > > > I wonder if we need to do this in vhost-vDPA.
> > > > >
> > > > > I don't get why we need to do this in vhost-vDPA? Should this be done in VM?
> > > >
> > > > If I was not wrong, this tries to set affinity on the host instead of
> > > > the guest. More below.
> > > >
> > >
> > > Yes, it's host stuff. This is used by the virtio device driver to pass
> > > the irq affinity hint (tell which irq vectors don't need affinity
> > > management) to the irq affinity manager. In the VM case, it should
> > > only be related to the guest's virtio device driver and pci irq
> > > affinity manager. So I don't get why we need to do this in vhost-vDPA.
> >
> > It's not necessarily the VM, do we have the same requirement for
> > userspace (like DPDK) drivers?
> >
>
> IIUC the vhost-vdpa's irq callback just signals the eventfd. I didn't
> see how to use the irq affinity hint in vdpa device driver. The real
> irq callback should be called in DPDK internally.
I agree.
Thanks
>
> Thanks,
> Yongji
>
_______________________________________________
Virtualization mailing list
Virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx
https://lists.linuxfoundation.org/mailman/listinfo/virtualization
