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

[Gupta, Anshuman]

> -----Original Message-----
> From: Nilawar, Badal <badal.nilawar at intel.com>
> Sent: Wednesday, November 20, 2024 1:44 PM
> To: Anirban, Sk <sk.anirban at intel.com>; intel-gfx at lists.freedesktop.org
> Cc: Gupta, Anshuman <anshuman.gupta at intel.com>; Poosa, Karthik
> <karthik.poosa at intel.com>; Pottumuttu, Sai Teja
> <sai.teja.pottumuttu at 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 at intel.com>
> > Reviewed-by: Sai Teja Pottumuttu <sai.teja.pottumuttu at 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.
> > +			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 ?

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;
> >   		}