[PATCH] drm/i915/gt: Track the overall busy time

[Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>]

Since we wake the GT up before executing a request, and go to sleep as
soon as it is retired, the GT wake time not only represents how long the
device is powered up, but also provides a summary, ableit overestimate,
of the device runtime.

Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
---
 drivers/gpu/drm/i915/gt/intel_gt_pm.c    | 45 ++++++++++++++++++++++++
 drivers/gpu/drm/i915/gt/intel_gt_pm.h    |  2 ++
 drivers/gpu/drm/i915/gt/intel_gt_types.h | 24 +++++++++++++
 drivers/gpu/drm/i915/i915_debugfs.c      |  2 ++
 4 files changed, 73 insertions(+)

diff --git a/drivers/gpu/drm/i915/gt/intel_gt_pm.c b/drivers/gpu/drm/i915/gt/intel_gt_pm.c
index 274aa0dd7050..ed8d7cf16118 100644
--- a/drivers/gpu/drm/i915/gt/intel_gt_pm.c
+++ b/drivers/gpu/drm/i915/gt/intel_gt_pm.c
@@ -39,6 +39,24 @@ static void user_forcewake(struct intel_gt *gt, bool suspend)
 	intel_gt_pm_put(gt);
 }
 
+static void runtime_begin(struct intel_gt *gt)
+{
+	write_seqcount_begin(&gt->stats.lock);
+	gt->stats.start = ktime_get();
+	gt->stats.active = true;
+	write_seqcount_end(&gt->stats.lock);
+}
+
+static void runtime_end(struct intel_gt *gt)
+{
+	write_seqcount_begin(&gt->stats.lock);
+	gt->stats.active = false;
+	gt->stats.total =
+		ktime_add(gt->stats.total,
+			  ktime_sub(ktime_get(), gt->stats.start));
+	write_seqcount_end(&gt->stats.lock);
+}
+
 static int __gt_unpark(struct intel_wakeref *wf)
 {
 	struct intel_gt *gt = container_of(wf, typeof(*gt), wakeref);
@@ -67,6 +85,7 @@ static int __gt_unpark(struct intel_wakeref *wf)
 	i915_pmu_gt_unparked(i915);
 
 	intel_gt_unpark_requests(gt);
+	runtime_begin(gt);
 
 	return 0;
 }
@@ -79,6 +98,7 @@ static int __gt_park(struct intel_wakeref *wf)
 
 	GT_TRACE(gt, "\n");
 
+	runtime_end(gt);
 	intel_gt_park_requests(gt);
 
 	i915_vma_parked(gt);
@@ -106,6 +126,7 @@ static const struct intel_wakeref_ops wf_ops = {
 void intel_gt_pm_init_early(struct intel_gt *gt)
 {
 	intel_wakeref_init(&gt->wakeref, gt->uncore->rpm, &wf_ops);
+	seqcount_init(&gt->stats.lock);
 }
 
 void intel_gt_pm_init(struct intel_gt *gt)
@@ -339,6 +360,30 @@ int intel_gt_runtime_resume(struct intel_gt *gt)
 	return intel_uc_runtime_resume(&gt->uc);
 }
 
+static ktime_t __intel_gt_get_busy_time(const struct intel_gt *gt)
+{
+	ktime_t total = gt->stats.total;
+
+	if (gt->stats.active)
+		total = ktime_add(total,
+				  ktime_sub(ktime_get(), gt->stats.start));
+
+	return total;
+}
+
+ktime_t intel_gt_get_busy_time(const struct intel_gt *gt)
+{
+	unsigned int seq;
+	ktime_t total;
+
+	do {
+		seq = read_seqcount_begin(&gt->stats.lock);
+		total = __intel_gt_get_busy_time(gt);
+	} while (read_seqcount_retry(&gt->stats.lock, seq));
+
+	return total;
+}
+
 #if IS_ENABLED(CONFIG_DRM_I915_SELFTEST)
 #include "selftest_gt_pm.c"
 #endif
diff --git a/drivers/gpu/drm/i915/gt/intel_gt_pm.h b/drivers/gpu/drm/i915/gt/intel_gt_pm.h
index 60f0e2fbe55c..aa8f2cda946b 100644
--- a/drivers/gpu/drm/i915/gt/intel_gt_pm.h
+++ b/drivers/gpu/drm/i915/gt/intel_gt_pm.h
@@ -58,6 +58,8 @@ int intel_gt_resume(struct intel_gt *gt);
 void intel_gt_runtime_suspend(struct intel_gt *gt);
 int intel_gt_runtime_resume(struct intel_gt *gt);
 
+ktime_t intel_gt_get_busy_time(const struct intel_gt *gt);
+
 static inline bool is_mock_gt(const struct intel_gt *gt)
 {
 	return I915_SELFTEST_ONLY(gt->awake == -ENODEV);
diff --git a/drivers/gpu/drm/i915/gt/intel_gt_types.h b/drivers/gpu/drm/i915/gt/intel_gt_types.h
index 6d39a4a11bf3..c8fcbca007e3 100644
--- a/drivers/gpu/drm/i915/gt/intel_gt_types.h
+++ b/drivers/gpu/drm/i915/gt/intel_gt_types.h
@@ -87,6 +87,30 @@ struct intel_gt {
 
 	u32 pm_guc_events;
 
+	struct {
+		bool active;
+
+		/**
+		 * @lock: Lock protecting the below fields.
+		 */
+		seqcount_t lock;
+
+		/**
+		 * @total: Total time this engine was busy.
+		 *
+		 * Accumulated time not counting the most recent block in cases
+		 * where engine is currently busy (active > 0).
+		 */
+		ktime_t total;
+
+		/**
+		 * @start: Timestamp of the last idle to active transition.
+		 *
+		 * Idle is defined as active == 0, active is active > 0.
+		 */
+		ktime_t start;
+	} stats;
+
 	struct intel_engine_cs *engine[I915_NUM_ENGINES];
 	struct intel_engine_cs *engine_class[MAX_ENGINE_CLASS + 1]
 					    [MAX_ENGINE_INSTANCE + 1];
diff --git a/drivers/gpu/drm/i915/i915_debugfs.c b/drivers/gpu/drm/i915/i915_debugfs.c
index 77e76b665098..337293c7bb7d 100644
--- a/drivers/gpu/drm/i915/i915_debugfs.c
+++ b/drivers/gpu/drm/i915/i915_debugfs.c
@@ -1316,6 +1316,8 @@ static int i915_engine_info(struct seq_file *m, void *unused)
 	seq_printf(m, "GT awake? %s [%d]\n",
 		   yesno(dev_priv->gt.awake),
 		   atomic_read(&dev_priv->gt.wakeref.count));
+	seq_printf(m, "GT busy: %llu ms\n",
+		   ktime_to_ms(intel_gt_get_busy_time(&dev_priv->gt)));
 	seq_printf(m, "CS timestamp frequency: %u Hz\n",
 		   RUNTIME_INFO(dev_priv)->cs_timestamp_frequency_hz);
 
-- 
2.20.1

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