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From: Jakub Kicinski <kuba@kernel.org>
To: Cong Wang <xiyou.wangcong@gmail.com>
Cc: David Miller <davem@davemloft.net>,
	Linux Kernel Network Developers <netdev@vger.kernel.org>,
	"Cong Wang ." <cong.wang@bytedance.com>,
	Peilin Ye <peilin.ye@bytedance.com>
Subject: Re: [PATCH net-next] Revert "netdevsim: Add multi-queue support"
Date: Tue, 3 Aug 2021 14:51:24 -0700	[thread overview]
Message-ID: <20210803145124.71a8aab4@kicinski-fedora-pc1c0hjn.dhcp.thefacebook.com> (raw)
In-Reply-To: <CAM_iQpV07aWSt5Jf-zSv6Qh4ydrJMYw54X3Seb8-eKGOpBYX7A@mail.gmail.com>

On Tue, 3 Aug 2021 14:32:19 -0700 Cong Wang wrote:
> On Tue, Aug 3, 2021 at 2:18 PM Jakub Kicinski <kuba@kernel.org> wrote:
> >
> > On Tue, 3 Aug 2021 10:11:13 -0700 Cong Wang wrote:  
> > > On Tue, Aug 3, 2021 at 5:39 AM Jakub Kicinski <kuba@kernel.org> wrote:  
> > > Since when netdevsim is *only* for upstream tests?  
> >
> > Since it was created.  
> 
> Why it was created only for upstream? IOW, what's wrong with
> using it only for non-upstream tests?
> 
> BTW, we also use dummy device for testing, it is not only for
> upstream. It is extremely odd to single netdevsim out. I don't
> see any special reason here.

From my own experience companies which are serious about their
engineering have a lot of code dedicated to testing. I don't think
we can deal with all such code upstream.

At the same time I want to incentivize upstreaming all of the tests
which are widely applicable (i.e. not HW-specific).

Last but not least test harnesses are really weird from functional, code
lifetime and refactoring perspective. netdevsim is not expected to keep
uAPI as long as in-tree tests do no break/are updated as well.

> > > Even if so, where is this documented? And why not just point it
> > > out when reviewing it instead of silently waiting for weeks?  
> >
> > I was AFK for the last two weeks.  
> 
> How about documenting it in netdev-FAQ (or literally any doc)?
> This would save everyone's time.

Fair, I'll send a patch.

> > > It is clearly not dead. We internally used it for testing sch_mq,
> > > this is clearly stated in the git log.  
> >
> > Please contribute those tests upstream or keep any test harness
> > they require where such test are, out of tree.  
> 
> Peilin will add tc-testing for sch_mq which requires this netdevsim
> feature.
> 
> >  
> > > How did you draw such a conclusion without talking to authors?  
> >
> > There is no upstream test using this code, and I did CC you, didn't I?  
> 
> There are downstream tests, which are mentioned in changelog.
> 
> I am pretty sure upstream tests only cover part of the whole networking
> code, if you really want to apply the rule, a lot of code are already dead.
> Once again, I don't see any reason why you only treat netdevsim differently.
> ;)

I hope the first part of this response scheds some light.

> > > But this does remind me of using netdevsim for tc-testing.  
> >
> > Please bring the code back as part of the series adding upstream tests.  
> 
> Please remove all those not covered by upstream tests just to be fair??

I'd love to remove all test harnesses upstream which are not used by
upstream tests, sure :)

  reply	other threads:[~2021-08-03 21:51 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-08-03 12:39 Jakub Kicinski
2021-08-03 17:11 ` Cong Wang
2021-08-03 21:18   ` Jakub Kicinski
2021-08-03 21:32     ` Cong Wang
2021-08-03 21:51       ` Jakub Kicinski [this message]
2021-08-03 22:04         ` Cong Wang
2021-08-04  7:14         ` Leon Romanovsky
2021-08-04 11:52           ` Jakub Kicinski
2021-08-04 12:49             ` Leon Romanovsky
2021-08-04 15:56               ` Jakub Kicinski
2021-08-04 17:25                 ` Leon Romanovsky
2021-08-03 22:16 ` [PATCH net-next] tc-testing: Add control-plane selftests for sch_mq Peilin Ye
2021-08-03 22:21   ` Cong Wang
2021-08-04 11:50   ` patchwork-bot+netdevbpf

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