[igt-dev] [PATCH i-g-t] tests/perf: add a test for OA data polling reads using "small" buffers

[Dixit, Ashutosh]

On Thu, 26 Mar 2020 02:02:40 -0700, Lionel Landwerlin wrote:
>
> On 26/03/2020 07:42, Ashutosh Dixit wrote:
> > Add a test for OA data non-blocking reads using buffers smaller than
> > the available data. This test would fail for perf revisions < 5
> > because poll would block even when data was available. Therefore the
> > amount of data read was limited by the buffer size and the timer
> > interval and it was impossible to read all available data. This issue
> > is fixed in perf revision 5.
>
>
> There seems to be a fundamental issue with this test, it's supposed to
> test a broken behavior with revision < 5 but then avoid testing anything
> there ;)

It was guaranteed to fail, but I see your point, you are saying let if fail
for rev < 5 but then submit the kernel patch as a fix.

> I've modified this test a bit here :
> https://gitlab.freedesktop.org/llandwerlin/igt-gpu-tools/-/tree/for-ashutosh
>
> It's failing stable kernels.
>
> Increasing the size of the buffer to 1Mb make the test pass.

I like it, I didn't know you could estimate the amount of OA data. I will
clean it up, test and post it as v2.

Thanks!
--
Ashutosh