[igt-dev] [PATCH i-g-t v2 3/3] tests/perf_pmu: Give sampling more time

[Chris Wilson]

Quoting Tvrtko Ursulin (2018-02-12 11:36:07)
> From: Tvrtko Ursulin <tvrtko.ursulin at intel.com>
> 
> We get occasional errors like:
> 
>  (perf_pmu:21315) CRITICAL: Test assertion failure function sema_wait, file perf_pmu.c:631:
>  (perf_pmu:21315) CRITICAL: Failed assertion: (double)(val[1] - val[0]) <= (1.0 + (tolerance)) * (double)(slept) && (double)(val[1] - val[0]) >= (1.0 - (tolerance)) * (double)(slept)
>  (perf_pmu:21315) CRITICAL: 'val[1] - val[0]' != 'slept' (450000000.000000 not within 5.000000% tolerance of 500129618.000000)
> 
> Suggesting a time disagreement between userspace and the PMU.
> 
> At the moment I got no better ideas than fiddling with delays to see if it
> improves things.
> 
> v2: Wait for sampling to start instead of hardcoded sleep. (Chris Wilson)
> 
> Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin at intel.com>
Reviewed-by: Chris Wilson <chris at chris-wilson.co.uk>

Sadly a consequence is going to be that 1ms minimum delay, but shucks.
I'm looking at the open-coded wait for batch to start next :)
-Chris