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

[Guo Zhi <qtxuning1999@sjtu.edu.cn>]

On 2022/7/21 17:17, Jason Wang wrote:
> On Thu, Jul 21, 2022 at 4:44 PM Guo Zhi <qtxuning1999@sjtu.edu.cn> 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
>>