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

[Chris Wilson]

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 at 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 at 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?
-Chris