Re: [PATCH i-g-t] tests/intel/xe_spin_batch: Check duration of preempter execution

[Rodrigo Vivi <rodrigo.vivi@intel.com>]

On Fri, Jun 21, 2024 at 01:53:03PM +0200, Francois Dugast wrote:
> The preempter is expected to execute without waiting, in a short
> time. The synchronous call takes roughly 1 ms under normal
> conditions.

is this true for any platform?

I'm asking this because sometimes we add things like this and this
becomes a 'committed KPI' and later when things start failing on
a platform we have regressions and escalations on a thing that
may be normal on that platform.

 This duration will be higher if the preempter is
> waiting. For example if the priorities are reversed in this test
> then this duration will be close to duration_ns (currently set
> to 100 ms) which was undetected by the test without this change.

Okay, so the goal of this change is to actually ensure that we
do not mess up with the test order itself? Any link reference
to this undetected case mentioned?

> 
> Signed-off-by: Francois Dugast <francois.dugast@intel.com>
> ---
>  tests/intel/xe_spin_batch.c | 8 +++++---
>  1 file changed, 5 insertions(+), 3 deletions(-)
> 
> diff --git a/tests/intel/xe_spin_batch.c b/tests/intel/xe_spin_batch.c
> index 4e95060d3..e57318801 100644
> --- a/tests/intel/xe_spin_batch.c
> +++ b/tests/intel/xe_spin_batch.c
> @@ -253,7 +253,7 @@ static void xe_spin_fixed_duration(int fd, int gt, int class, int flags)
>  	uint64_t ext = 0;
>  	size_t bo_size;
>  	struct xe_spin *spin;
> -	struct timespec tv;
> +	struct timespec tv, tv_preempter;
>  	double elapsed_ms;
>  	igt_stats_t stats;
>  	int i;
> @@ -289,9 +289,11 @@ static void xe_spin_fixed_duration(int fd, int gt, int class, int flags)
>  		igt_gettime(&tv);
>  		xe_exec(fd, &exec);
>  		xe_spin_wait_started(spin);
> -		if (flags & SPIN_FIX_DURATION_PREEMPT)
> +		if (flags & SPIN_FIX_DURATION_PREEMPT) {
> +			igt_gettime(&tv_preempter);
>  			preempter(fd, hwe);
> -
> +			igt_assert(igt_nsec_elapsed(&tv_preempter) * 1e-6 < 10);
> +		}
>  		igt_assert(syncobj_wait(fd, &sync.handle, 1, INT64_MAX, 0, NULL));
>  		igt_stats_push_float(&stats, igt_nsec_elapsed(&tv) * 1e-6);
>  		syncobj_reset(fd, &sync.handle, 1);
> -- 
> 2.43.0
>