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* [Intel-gfx] [PATCH] drm/i915/pmu: Match frequencies reported by PMU and sysfs
@ 2022-10-03 19:24 Ashutosh Dixit
  2022-10-03 23:34 ` [Intel-gfx] ✓ Fi.CI.BAT: success for " Patchwork
                   ` (2 more replies)
  0 siblings, 3 replies; 7+ messages in thread
From: Ashutosh Dixit @ 2022-10-03 19:24 UTC (permalink / raw)
  To: intel-gfx; +Cc: dri-devel

PMU and sysfs use different wakeref's to "interpret" zero freq. Sysfs uses
runtime PM wakeref (see intel_rps_read_punit_req and
intel_rps_read_actual_frequency). PMU uses the GT parked/unparked
wakeref. In general the GT wakeref is held for less time that the runtime
PM wakeref which causes PMU to report a lower average freq than the average
freq obtained from sampling sysfs.

To resolve this, use the same freq functions (and wakeref's) in PMU as
those used in sysfs.

Bug: https://gitlab.freedesktop.org/drm/intel/-/issues/7025
Reported-by: Ashwin Kumar Kulkarni <ashwin.kumar.kulkarni@intel.com>
Cc: Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>
Signed-off-by: Ashutosh Dixit <ashutosh.dixit@intel.com>
---
 drivers/gpu/drm/i915/i915_pmu.c | 27 ++-------------------------
 1 file changed, 2 insertions(+), 25 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_pmu.c b/drivers/gpu/drm/i915/i915_pmu.c
index 958b37123bf1..eda03f264792 100644
--- a/drivers/gpu/drm/i915/i915_pmu.c
+++ b/drivers/gpu/drm/i915/i915_pmu.c
@@ -371,37 +371,16 @@ static void
 frequency_sample(struct intel_gt *gt, unsigned int period_ns)
 {
 	struct drm_i915_private *i915 = gt->i915;
-	struct intel_uncore *uncore = gt->uncore;
 	struct i915_pmu *pmu = &i915->pmu;
 	struct intel_rps *rps = &gt->rps;
 
 	if (!frequency_sampling_enabled(pmu))
 		return;
 
-	/* Report 0/0 (actual/requested) frequency while parked. */
-	if (!intel_gt_pm_get_if_awake(gt))
-		return;
-
 	if (pmu->enable & config_mask(I915_PMU_ACTUAL_FREQUENCY)) {
-		u32 val;
-
-		/*
-		 * We take a quick peek here without using forcewake
-		 * so that we don't perturb the system under observation
-		 * (forcewake => !rc6 => increased power use). We expect
-		 * that if the read fails because it is outside of the
-		 * mmio power well, then it will return 0 -- in which
-		 * case we assume the system is running at the intended
-		 * frequency. Fortunately, the read should rarely fail!
-		 */
-		val = intel_uncore_read_fw(uncore, GEN6_RPSTAT1);
-		if (val)
-			val = intel_rps_get_cagf(rps, val);
-		else
-			val = rps->cur_freq;
-
 		add_sample_mult(&pmu->sample[__I915_SAMPLE_FREQ_ACT],
-				intel_gpu_freq(rps, val), period_ns / 1000);
+				intel_rps_read_actual_frequency(rps),
+				period_ns / 1000);
 	}
 
 	if (pmu->enable & config_mask(I915_PMU_REQUESTED_FREQUENCY)) {
@@ -409,8 +388,6 @@ frequency_sample(struct intel_gt *gt, unsigned int period_ns)
 				intel_rps_get_requested_frequency(rps),
 				period_ns / 1000);
 	}
-
-	intel_gt_pm_put_async(gt);
 }
 
 static enum hrtimer_restart i915_sample(struct hrtimer *hrtimer)
-- 
2.34.1


^ permalink raw reply related	[flat|nested] 7+ messages in thread
end of thread, other threads:[~2022-10-05  7:52 UTC | newest]

Thread overview: 7+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2022-10-03 19:24 [Intel-gfx] [PATCH] drm/i915/pmu: Match frequencies reported by PMU and sysfs Ashutosh Dixit
2022-10-03 23:34 ` [Intel-gfx] ✓ Fi.CI.BAT: success for " Patchwork
2022-10-04  6:20 ` [Intel-gfx] ✗ Fi.CI.IGT: failure " Patchwork
2022-10-04  9:29 ` [Intel-gfx] [PATCH] " Tvrtko Ursulin
2022-10-04 13:00   ` Tvrtko Ursulin
2022-10-04 13:05     ` Tvrtko Ursulin
2022-10-05  7:40     ` Dixit, Ashutosh

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