Linux Virtualization - Oct 2018 - [virtio-dev] Re: [PATCH net-next v2 0/5] virtio: support packed ring

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.

-- 
MST

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!

> 
> -- 
> MST

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.

> 
> > 
> > -- 
> > MST