[igt-dev] [PATCH i-g-t] lib/igt_dummyload: Helper to spin till a specified timeout

[Ashutosh Dixit]

On Wed, 29 May 2019 23:56:43 -0700, Chris Wilson wrote:
>
> Quoting Ashutosh Dixit (2019-05-30 06:26:41)
> > From: "Dixit, Ashutosh" <ashutosh.dixit at intel.com>
> >
> > Even though similar functionality exists in other tests, perhaps there
> > is value in having a helper function which generates an artificial
> > load on an engine by spinning on it for a specified time.
>
> That seems very odd. As you aren't doing anything else during the spin,
> what is its purpose for general testing? i.e. where would one use it.
> With new interfaces, it is always useful to show how you plan to use it
> so that we can better understand the bigger picture.

This approach has proved useful to us on new hardware in validating simple
cases such as: (a) spin batch submission and completion timestamps reported
by the kernel are the same as the time specified in the test (b) spin
batches submitted on multiple engines are in fact executing in parallel
(easy to check due to the rather large timeout). Perhaps these are self
evident conditions which do not need to be checked at all.

The test is really a simpler version of the functionality already present
in gem_spin_batch.c (though the test itself doesn't "test" for any
condition). It is for these reasons that I posted the patch in case people
thought it was useful. If it's not we can drop it. Thanks!
--
Ashutosh