Re: [dpdk-dev] [PATCH] virtio: fix the vq size issue

[Thomas Monjalon <thomas.monjalon@6wind.com>]

2015-07-20 06:18, Ouyang, Changchun:
> Another thing burst into my thought.
> Can we think more about how to setup a mechanism to block those patches which causes critical regression issue?

Yes. Non-regression tests are needed. As it must be done with many hardwares
and many configurations, it must be a shared effort.
As a first step, you can run some automated tests by yourself and *manually*
raise errors on the mailing lists. When it will work well, we could discuss
about gathering test reports in a clean distributed way.
Note that this topic is already a work in progress by few people and a public
proposal should be done in few weeks.

> I did review that patch before, but fail to realize it will break the basic function of virtio PMD, it is my bad. 
> (Can I send the nack to that patch even after it has been merged into dpdk.org?)

After being approved and merged, a nack has no effect.
Having a revert approved is the good way.

> After that, we find that in our testing cycle, we spend time in investigating that and root the cause, and sent out
> the fixing patch on July 1.  Keeping virtio basic functionality broken more than 20 days is bad thing for me.

It wouldn't be so long if these 3 simple things were done:
- use a better title: "virtio: fix Rx from Qemu" instead of a not meaningful "fix the vq size issue"
- cc Stephen (I did it later) who did the original patch you wants to revert
- have an acked-by from Huawei Xie who commented the patch

> If we can run a regression automation test with every patch set sent out to dpdk.org, and put those patches breaking any test cases
> Into failing-list and notify author, reviewer and maintainer, all those things should be done before theirs being merged, then it will
> prevent from merging the erroneous patch into mainline, and thus reduce most reverting patch.

As explained above, it is planned and you can start running you own local test
machine. But please do not spam the mailing list with automated mails from
these tests.