Re: [PATCH v5 01/18] kunit: test: add KUnit test runner core

From: Luis Chamberlain <mcgrof@kernel.org>
To: Brendan Higgins <brendanhiggins@google.com>
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Subject: Re: [PATCH v5 01/18] kunit: test: add KUnit test runner core
Date: Tue, 25 Jun 2019 23:02:53 +0000	[thread overview]
Message-ID: <20190625230253.GQ19023@42.do-not-panic.com> (raw)
In-Reply-To: <CAFd5g47OABqN127cPKqoCOA_Wr9w=LFh_0XkF7LXu2iY9sFkSw@mail.gmail.com>

On Tue, Jun 25, 2019 at 03:14:45PM -0700, Brendan Higgins wrote:
> On Tue, Jun 25, 2019 at 2:44 PM Luis Chamberlain <mcgrof@kernel.org> wrote:
> > Since its a new architecture and since you seem to imply most tests
> > don't require locking or even IRQs disabled, I think its worth to
> > consider the impact of adding such extreme locking requirements for
> > an initial ramp up.
> 
> Fair enough, I can see the point of not wanting to use irq disabled
> until we get someone complaining about it, but I think making it
> thread safe is reasonable. It means there is one less thing to confuse
> a KUnit user and the only penalty paid is some very minor performance.

One reason I'm really excited about kunit is speed... so by all means I
think we're at a good point to analyze performance optimizationsm if
they do make sense.

While on the topic of parallization, what about support for running
different test cases in parallel? Or at the very least different kunit
modules in parallel.  Few questions come up based on this prospect:

  * Why not support parallelism from the start?
  * Are you opposed to eventually having this added? For instance, there is
    enough code on lib/test_kmod.c for batching tons of kthreads each
    one running its own thing for testing purposes which could be used
    as template.
  * If we eventually *did* support it:
    - Would logs be skewed?
    - Could we have a way to query: give me log for only kunit module
      named "foo"?

  Luis

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