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:

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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!

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MST