[dpdk-dev] [PATCH v3 0/5] vhost: optimize enqueue

[Maxime Coquelin]

On 10/13/2016 09:54 AM, Maxime Coquelin wrote:
>
>
> On 10/13/2016 08:02 AM, Wang, Zhihong wrote:
>>> > Yes, that's great effort! With your hardwork, we know what the
>>> bottleneck
>>> > is and how it could be improved.
>>> >
>>> > However, you don't have to do code refactor (merge two code path to
>>> one)
>>> > to apply those improvements. From what I know, in this patchset, there
>>> > are two factors could improve the performance:
>>> >
>>> > - copy hdr together with packet data
>>> >
>>> > - shadow used ring update and update at once
>>> >
>>> > The overall performance boost I got with your v6 patchset with mrg-Rx
>>> > code path is about 27% (in PVP case). And I have just applied the 1st
>>> > optimization, it yields about 20% boosts. The left could be covered if
>>> > we apply the 2nd optimization (I guess).
>>> >
>>> > That would be a clean way to optimize vhost mergeable Rx path:
>>> >
>>> > - you don't touch non-mrg Rx path (well, you may could apply the
>>> >   shadow_used_ring trick to it as wel)
>>> >
>>> >   This would at least make sure we will have no such performance
>>> >   regression issue reported by ARM guys.
>>> >
>>> > - you don't refactor the code
>>> >
>>> >   The rewrite from scratch could introduce other issues, besides the
>>> >   performance regression. We may just don't know it yet.
>>> >
>>> >
>>> > Make sense to you? If you agree, I think we could still make it in
>>> > this release: they would be some small changes after all. For example,
>>> > below is the patch applies the 1st optimization tip on top of
>>> > dpdk-next-virtio
>>
>> Thanks for this great idea. I think it's a better way to do it.
>> I'll start to make the patch then.
>>
>>
>
> I personally find having two paths better for maintenance as it is
> easier to understand (IMHO).
> So if we can have the performance gain while keeping the two paths,
> I definitely support the idea.

I was going to re-run some PVP benchmark with 0% pkt loss, as I had
some strange results last week.

Problem is that your series no more apply cleanly due to
next-virtio's master branch history rewrite.
Any chance you send me a rebased version so that I can apply the series?

Thanks,
Maxime