Re: [PATCH net-next] Revert "netdevsim: Add multi-queue support"

On Tue, Aug 3, 2021 at 2:18 PM Jakub Kicinski [off-list ref] wrote:

On Tue, 3 Aug 2021 10:11:13 -0700 Cong Wang wrote:

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On Tue, Aug 3, 2021 at 5:39 AM Jakub Kicinski [off-list ref] wrote:

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This reverts commit d4861fc6be581561d6964700110a4dede54da6a6.

netdevsim is for enabling upstream tests, two weeks in
and there's no sign of upstream test using the "mutli-queue"
option.

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.

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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.

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We can add this option back when such test materializes.
Right now it's dead code.

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.

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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.
;)

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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??

Thank you!