Re: [PATCH v6] drm/i915/selftests: Implement frequency logging for energy reading validation

["Nilawar, Badal" <badal.nilawar@intel.com>]

On 20-11-2024 16:00, Gupta, Anshuman wrote:
> 
> 
>> -----Original Message-----
>> From: Nilawar, Badal <badal.nilawar@intel.com>
>> Sent: Wednesday, November 20, 2024 1:44 PM
>> To: Anirban, Sk <sk.anirban@intel.com>; intel-gfx@lists.freedesktop.org
>> Cc: Gupta, Anshuman <anshuman.gupta@intel.com>; Poosa, Karthik
>> <karthik.poosa@intel.com>; Pottumuttu, Sai Teja
>> <sai.teja.pottumuttu@intel.com>
>> Subject: Re: [PATCH v6] drm/i915/selftests: Implement frequency logging for
>> energy reading validation
>>
>>
>>
>> On 13-11-2024 15:20, 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)
>>> v6:
>>>     - Modify debug logging for RC0 power and frequency checks (Sai
>>> Teja)
>>>
>>> Signed-off-by: Sk Anirban <sk.anirban@intel.com>
>>> Reviewed-by: Sai Teja Pottumuttu <sai.teja.pottumuttu@intel.com>
>>> ---
>>>    drivers/gpu/drm/i915/gt/selftest_rc6.c | 15 +++++++++++++--
>>>    1 file changed, 13 insertions(+), 2 deletions(-)
>>>
>>> diff --git a/drivers/gpu/drm/i915/gt/selftest_rc6.c
>>> b/drivers/gpu/drm/i915/gt/selftest_rc6.c
>>> index 1aa1446c8fb0..a8776f88d6a1 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);
>>> @@ -77,7 +82,11 @@ 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");
>>> +			if (rc0_freq)
>>> +				pr_err("No power measured while in RC0!
>> GPU Freq: %u in RC0\n",
>>> +				       rc0_freq);
> If rc0 frequency is there then, this has to be pr_dbg, otherwise what is the purpose of this patch.

I too didn't understand purpose of this. How this going to help for 
accurate energy readings.

>>> +			else
>>> +				pr_err("No power and freq measured while in
>> RC0\n");
>>>    			err = -EINVAL;
>>>    			goto out_unlock;
>>>    		}
>>> @@ -91,6 +100,7 @@ int live_rc6_manual(void *arg)
>>>    	dt = ktime_get();
>>>    	rc6_power = librapl_energy_uJ();
>>>    	msleep(100);
>>> +	rc6_freq = intel_rps_read_actual_frequency(rps);
>>
>> I think intention of reading frequency here is to know if device was not in RC6
>> when there is failure. But for the platforms below gen12 reading act frequency
>> will cause gt wake as GEN6_RPSTAT reg requires forcewake.
>> To avoid wake when device is in RC6 read actual frequency without applying
>> forcewake.
> If reading act_freq will wake the device, How to read frequency without forcewake then ?

Use this api intel_rps_read_actual_frequency_fw to read freq without 
forcewake.

Regards,
Badal

> 
> Thanks,
> Anshuaman
>>
>> Additionally add delay, may be delay of 1 seconds after re-enabling RC6
>> manually and forcewake flush.
>>
>> Regards,
>> Badal
>>
>>>    	rc6_power = librapl_energy_uJ() - rc6_power;
>>>    	dt = ktime_sub(ktime_get(), dt);
>>>    	res[1] = rc6_residency(rc6);
>>> @@ -108,7 +118,8 @@ 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;
>>>    		}
>