Virtualization - Nov 2022 - [PATCH 3/6] vduse: Add sysfs interface for irq affinity setup

On Tue, Nov 15, 2022 at 10:49 AM Yongji Xie <xieyongji at bytedance.com>
wrote:
>
> On Mon, Nov 14, 2022 at 4:55 PM Jason Wang <jasowang at redhat.com>
wrote:
> >
> > On Mon, Nov 14, 2022 at 4:20 PM Yongji Xie <xieyongji at
bytedance.com> wrote:
> > >
> > > On Mon, Nov 14, 2022 at 3:58 PM Jason Wang <jasowang at
redhat.com> wrote:
> > > >
> > > > On Mon, Nov 14, 2022 at 3:16 PM Xie Yongji <xieyongji at
bytedance.com> wrote:
> > > > >
> > > > > Add sysfs interface for each vduse virtqueue to setup
> > > > > irq affinity. This would be useful for performance
> > > > > tuning, e.g., mitigate the virtqueue lock contention
> > > > > in virtio block driver.
> > > >
> > > > Do we have any perforamnce numbers for this?
> > > >
> > >
> > > Almost 50% improvement (600k iops -> 900k iops) in the high
iops
> > > workloads. I have mentioned it in the cover-letter.
> >
> > For some reason, I miss that.
> >
> > I also wonder if we can do this automatically, then there's no
need to
> > play with sysfs which is kind of a burden for the management layer.
> >
>
> This is hard to do since vduse doesn't know which cpu should be bound
> for a certain virtqueue.
Probably via the kick_vq()? It probably won't work when notification
is disabled. But we need to think a little bit more about this.
Requiring management software to do ad-hoc running just for VDUSE
seems not easy.

Thanks
>
> Thanks,
> Yongji
>