Re: [RFC 0/5] In virtio-spec 1.1, new feature bit VIRTIO_F_IN_ORDER was introduced.

[Guo Zhi]

On 2022/7/21 17:17, Jason Wang wrote:
> On Thu, Jul 21, 2022 at 4:44 PM Guo Zhi <qtxuning1999@xxxxxxxxxxx> wrote:
> > When this feature has been negotiated, virtio driver will use
> > descriptors in ring order: starting from offset 0 in the table, and
> > wrapping around at the end of the table. Vhost devices will always use
> > descriptors in the same order in which they have been made available.
> > This can reduce virtio accesses to used ring.
> >
> > Based on updated virtio-spec, this series realized IN_ORDER prototype
> > in virtio driver and vhost.
> Thanks a lot for the series.
>
> I wonder if you can share any performance numbers for this?
>
> Thanks

As a RFC series, current prototype only support virtio_test, and its 
performance evaluation between

in order and traditional has little difference. We can focus on the 
prototype design at this stage.

I will continue work to support real network driver and device, thus 
share more persuasive performance result.

Thanks.

> > Guo Zhi (5):
> >    vhost: reorder used descriptors in a batch
> >    vhost: announce VIRTIO_F_IN_ORDER support
> >    vhost_test: batch used buffer
> >    virtio: get desc id in order
> >    virtio: annouce VIRTIO_F_IN_ORDER support
> >
> >   drivers/vhost/test.c         | 15 +++++++++++-
> >   drivers/vhost/vhost.c        | 44 ++++++++++++++++++++++++++++++++++--
> >   drivers/vhost/vhost.h        |  4 ++++
> >   drivers/virtio/virtio_ring.c | 39 +++++++++++++++++++++++++-------
> >   4 files changed, 91 insertions(+), 11 deletions(-)
> >
> > --
> > 2.17.1