Re: [PATCH i-g-t 2/3] tests/perf_pmu: Simplify interrupt testing

[Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>]

On 20/12/2017 10:49, Chris Wilson wrote:
> Quoting Tvrtko Ursulin (2017-12-20 09:45:41)
>>
>> On 19/12/2017 21:45, Chris Wilson wrote:
>>> Quoting Tvrtko Ursulin (2017-12-19 15:45:42)
>>>> From: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
>>>>
>>>> Rather than calibrate and emit nop batches, use a manually signalled chain
>>>> of spinners to generate the desired interrupts.
>>>>
>>>> Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
>>>> ---
>>>> -       /* Unplug the calibrated queue and wait for all the fences */
>>>> -       igt_spin_batch_free(gem_fd, spin);
>>>> -       igt_assert_eq(poll(&pfd, 1, 2 * test_duration_ms), 1);
>>>> -       close(pfd.fd);
>>>> +               pfd.fd = spin[i]->out_fence;
>>>> +               igt_spin_batch_set_timeout(spin[i], timeout_ms * 1e6);
>>>> +               igt_assert_eq(poll(&pfd, 1, 2 * timeout_ms), 1);
>>>
>>> Oh, still with the synchronous behaviour, bleurgh.
>>
>> I was attracted by the simplicity of this approach, but I can change to
>> set incremental timeouts and keep the merged fence if you think that's
>> better?
> 
> It was mostly surprise as I just have a preference for setting up
> everything and then letting it go; fire-and-forget style. So that was
> what I was expecting to see. It should basically be the difference of
> adding a single function to merge the fences (albeit you have to write
> that function). Shall we say both patterns have merit / analogues to the
> real world?

It is using fence merging approach so it won't be a problem to keep 
that, just with the spin batches. I mostly wanted to remove calibration 
since you were nudging me in that direction. Don't mind really of the 
specific mechanics of emitting interrupts so I am happy to go back a step.

Regards,

Tvrtko
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