Re: [igt-dev] [PATCH v2] tests/perf: Fix timeout for RC6 re-enabling

[Lionel Landwerlin <lionel.g.landwerlin@intel.com>]

On 16/04/2019 15:09, Imre Deak wrote:
> After closing the perf stream the parking the GPU engines may easily
> take more than 1 second: releasing the FD itself results in a new
> request submission via i915_perf_release()->i915_oa_stream_destroy()->
> gen8_disable_metric_set(). That means a >1sec delay for the delayed
> unpark to be called due to the delay from
>
>   queue_delayed_work(retire_work, round_jiffies_up_relative(HZ))
>
> + the delay from
>
>   mod_delayed_work(idle_work, msecs_to_jiffies(100))
>
> Scheduling may push this delay even further, I measured >2sec delays on
> my GLK.
>
> Fix this by calling gem_quiescent_gpu() which syncs up with the idle
> work, thus making sure we'll see RC6 residency afterwards.
>
> v2:
> - Use gem_quiescent_gpu() instead of increasing the timeout. (Chris)
>
> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=103179
> Cc: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
> Cc: Chris Wilson <chris@chris-wilson.co.uk>
> Signed-off-by: Imre Deak <imre.deak@intel.com>


Reviewed-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>


> ---
>   tests/perf.c | 1 +
>   1 file changed, 1 insertion(+)
>
> diff --git a/tests/perf.c b/tests/perf.c
> index 4307d36a..f2c0aeb8 100644
> --- a/tests/perf.c
> +++ b/tests/perf.c
> @@ -3604,6 +3604,7 @@ test_rc6_disable(void)
>   	igt_assert_eq(n_events_end - n_events_start, 0);
>   
>   	__perf_close(stream_fd);
> +	gem_quiescent_gpu(drm_fd);
>   
>   	n_events_start = rc6_residency_ms();
>   	nanosleep(&(struct timespec){ .tv_sec = 1, .tv_nsec = 0 }, NULL);


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