[Intel-gfx] [PATCH] drm/i915/selftests: Tweak the tolerance for clock ticks to 12.5%

[Mika Kuoppala]

Chris Wilson <chris at chris-wilson.co.uk> writes:

> Give a small bump for our tolerance on comparing the expected vs
> measured clock ticks/time from 10% to 12.5% to accommodate a bad result
> on Sandybridge that was off by 10.3%. Hopefully, that is the worst we
> will see.
>
> Closes: https://gitlab.freedesktop.org/drm/intel/-/issues/1802
> Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>

12.5% of something is much better than 100% of nothing

Reviewed-by: Mika Kuoppala <mika.kuoppala at linux.intel.com>

> ---
>  drivers/gpu/drm/i915/gt/selftest_rps.c | 8 ++++----
>  1 file changed, 4 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/gt/selftest_rps.c b/drivers/gpu/drm/i915/gt/selftest_rps.c
> index 181b29fa5b58..48f954ac4f2c 100644
> --- a/drivers/gpu/drm/i915/gt/selftest_rps.c
> +++ b/drivers/gpu/drm/i915/gt/selftest_rps.c
> @@ -312,15 +312,15 @@ int live_rps_clock_interval(void *arg)
>  				engine->name, cycles, time, ktime_to_ns(dt), expected,
>  				gt->clock_frequency / 1000);
>  
> -			if (10 * time < 9 * ktime_to_ns(dt) ||
> -			    10 * time > 11 * ktime_to_ns(dt)) {
> +			if (10 * time < 8 * ktime_to_ns(dt) ||
> +			    8 * time > 10 * ktime_to_ns(dt)) {
>  				pr_err("%s: rps clock time does not match walltime!\n",
>  				       engine->name);
>  				err = -EINVAL;
>  			}
>  
> -			if (10 * expected < 9 * cycles ||
> -			    10 * expected > 11 * cycles) {
> +			if (10 * expected < 8 * cycles ||
> +			    8 * expected > 10 * cycles) {
>  				pr_err("%s: walltime does not match rps clock ticks!\n",
>  				       engine->name);
>  				err = -EINVAL;
> -- 
> 2.20.1
>
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