Re: [PATCH v5] drm/i915/selftests: Implement frequency logging for energy reading validation

["Pottumuttu, Sai Teja" <sai.teja.pottumuttu@xxxxxxxxx>]

On 10-10-2024 23:04, Sk Anirban wrote:
> Introduce RC6 & RC0 frequency logging mechanism to ensure accurate
> energy readings aimed at addressing GPU energy leaks and power
> measurement failures.
> This enhancement will help ensure the accuracy of energy readings.
>
> v2:
>    - Improved commit message.
> v3:
>    - Used pr_err log to display frequency (Anshuman)
>    - Sorted headers alphabetically (Sai Teja)
> v4:
>    - Improved commit message
>    - Fix pr_err log (Sai Teja)
> v5:
>    -Add error & debug logging for RC0 power and frequency checks (Anshuman)
>
> Signed-off-by: Sk Anirban <sk.anirban@xxxxxxxxx>
> Reviewed-by: Sai Teja Pottumuttu <sai.teja.pottumuttu@xxxxxxxxx>
> ---
>   drivers/gpu/drm/i915/gt/selftest_rc6.c | 20 ++++++++++++++++----
>   1 file changed, 16 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/gt/selftest_rc6.c b/drivers/gpu/drm/i915/gt/selftest_rc6.c
> index 1aa1446c8fb0..0cf86fed39ca 100644
> --- a/drivers/gpu/drm/i915/gt/selftest_rc6.c
> +++ b/drivers/gpu/drm/i915/gt/selftest_rc6.c
> @@ -8,6 +8,7 @@
>   #include "intel_gpu_commands.h"
>   #include "intel_gt_requests.h"
>   #include "intel_ring.h"
> +#include "intel_rps.h"
>   #include "selftest_rc6.h"
>   
>   #include "selftests/i915_random.h"
> @@ -38,6 +39,9 @@ int live_rc6_manual(void *arg)
>   	ktime_t dt;
>   	u64 res[2];
>   	int err = 0;
> +	u32 rc0_freq = 0;
> +	u32 rc6_freq = 0;
> +	struct intel_rps *rps = &gt->rps;
>   
>   	/*
>   	 * Our claim is that we can "encourage" the GPU to enter rc6 at will.
> @@ -66,6 +70,7 @@ int live_rc6_manual(void *arg)
>   	rc0_power = librapl_energy_uJ() - rc0_power;
>   	dt = ktime_sub(ktime_get(), dt);
>   	res[1] = rc6_residency(rc6);
> +	rc0_freq = intel_rps_read_actual_frequency(rps);
>   	if ((res[1] - res[0]) >> 10) {
>   		pr_err("RC6 residency increased by %lldus while disabled for 1000ms!\n",
>   		       (res[1] - res[0]) >> 10);
> @@ -77,9 +82,14 @@ int live_rc6_manual(void *arg)
>   		rc0_power = div64_u64(NSEC_PER_SEC * rc0_power,
>   				      ktime_to_ns(dt));
>   		if (!rc0_power) {
> -			pr_err("No power measured while in RC0\n");
> -			err = -EINVAL;
> -			goto out_unlock;
> +			if (rc0_freq)
> +				pr_debug("No power measured while in RC0! GPU Freq: %u in RC0\n",
> +			rc0_freq);
This line is not indented properly.
> +			else {
> +				pr_err("No power and freq measured while in RC0\n");
> +				err = -EINVAL;
> +				goto out_unlock;
AFAIU we should have the EINVAL and goto out_unlock irrespective of 
rc0_freq. Reason being, if rc0_power is not measured then the comparison 
we are doing with rc6_power below becomes invalid so I think we 
shouldn't proceed if rc0_power is not measured and just goto out_unlock 
with EINVAL. Am I missing something?
> +			}
>   		}
>   	}
>   
> @@ -91,6 +101,7 @@ int live_rc6_manual(void *arg)
>   	dt = ktime_get();
>   	rc6_power = librapl_energy_uJ();
>   	msleep(100);
> +	rc6_freq = intel_rps_read_actual_frequency(rps);
>   	rc6_power = librapl_energy_uJ() - rc6_power;
>   	dt = ktime_sub(ktime_get(), dt);
>   	res[1] = rc6_residency(rc6);
> @@ -108,7 +119,8 @@ int live_rc6_manual(void *arg)
>   		pr_info("GPU consumed %llduW in RC0 and %llduW in RC6\n",
>   			rc0_power, rc6_power);
>   		if (2 * rc6_power > rc0_power) {
> -			pr_err("GPU leaked energy while in RC6!\n");
> +			pr_err("GPU leaked energy while in RC6! GPU Freq: %u in RC6 and %u in RC0\n",
> +			       rc6_freq, rc0_freq);
>   			err = -EINVAL;
>   			goto out_unlock;
>   		}