Re: [virtio-dev] Re: [PATCH net-next v2 0/5] virtio: support packed ring

[Tiwei Bie]

On Thu, Oct 11, 2018 at 10:17:15AM -0400, Michael S. Tsirkin wrote:
> On Thu, Oct 11, 2018 at 10:13:31PM +0800, Tiwei Bie wrote:
> > On Thu, Oct 11, 2018 at 09:48:48AM -0400, Michael S. Tsirkin wrote:
> > > On Thu, Oct 11, 2018 at 08:12:21PM +0800, Tiwei Bie wrote:
> > > > > > But if it's not too late, I second for a OUT_OF_ORDER feature.
> > > > > > Starting from in order can have much simpler code in driver.
> > > > > > 
> > > > > > Thanks
> > > > > 
> > > > > It's tricky to change the flag polarity because of compatibility
> > > > > with legacy interfaces. Why is this such a big deal?
> > > > > 
> > > > > Let's teach drivers about IN_ORDER, then if devices
> > > > > are in order it will get enabled by default.
> > > > 
> > > > Yeah, make sense.
> > > > 
> > > > Besides, I have done some further profiling and debugging
> > > > both in kernel driver and DPDK vhost. Previously I was mislead
> > > > by a bug in vhost code. I will send a patch to fix that bug.
> > > > With that bug fixed, the performance of packed ring in the
> > > > test between kernel driver and DPDK vhost is better now.
> > > 
> > > OK, if we get a performance gain on the virtio side, we can finally
> > > upstream it. If you see that please re-post ASAP so we can
> > > put it in the next kernel release.
> > 
> > Got it, I will re-post ASAP.
> > 
> > Thanks!
> 
> 
> Pls remember to include data on performance gain in the cover letter.

Sure. I'll try to include some performance analyses.