On 11/09/2019 17:38, Chris Wilson wrote:
As we track when we put the GT device to sleep upon idling, we can use
that callback to sample the current rc6 counters and record the
timestamp for estimating samples after that point while asleep.

v2: Stick to using ktime_t
v3: Track user_wakerefs that interfere with the new
intel_gt_pm_wait_for_idle

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=105010
Signed-off-by: Chris Wilson <ch...@chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursu...@intel.com>
---
  drivers/gpu/drm/i915/gem/i915_gem_pm.c   |  19 ++++
  drivers/gpu/drm/i915/gt/intel_gt_types.h |   1 +
  drivers/gpu/drm/i915/i915_debugfs.c      |  22 ++---
  drivers/gpu/drm/i915/i915_pmu.c          | 120 +++++++++++------------
  drivers/gpu/drm/i915/i915_pmu.h          |   4 +-
  5 files changed, 90 insertions(+), 76 deletions(-)

diff --git a/drivers/gpu/drm/i915/gem/i915_gem_pm.c 
b/drivers/gpu/drm/i915/gem/i915_gem_pm.c
index 3bd764104d41..45a72cb698db 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_pm.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_pm.c
@@ -141,6 +141,21 @@ bool i915_gem_load_power_context(struct drm_i915_private 
*i915)
        return switch_to_kernel_context_sync(&i915->gt);
  }
+static void user_forcewake(struct intel_gt *gt, bool suspend)
+{
+       int count = atomic_read(&gt->user_wakeref);
+
+       if (likely(!count))
+               return;
+
+       intel_gt_pm_get(gt);
+       if (suspend)
+               atomic_sub(count, &gt->wakeref.count);
+       else
+               atomic_add(count, &gt->wakeref.count);
+       intel_gt_pm_put(gt);
+}
+
  void i915_gem_suspend(struct drm_i915_private *i915)
  {
        GEM_TRACE("\n");
@@ -148,6 +163,8 @@ void i915_gem_suspend(struct drm_i915_private *i915)
        intel_wakeref_auto(&i915->ggtt.userfault_wakeref, 0);
        flush_workqueue(i915->wq);
+ user_forcewake(&i915->gt, true);

This complication is needed only because you changed user forcewake handling to use intel_gt_pm_get/put instead of intel_runtime_pm_get? Which in turn is because of the CONFIG_PM ifdef removal below? Wouldn't it be simpler to keep both as were? Maybe I am missing something...

+
        mutex_lock(&i915->drm.struct_mutex);
/*
@@ -259,6 +276,8 @@ void i915_gem_resume(struct drm_i915_private *i915)
        if (!i915_gem_load_power_context(i915))
                goto err_wedged;
+ user_forcewake(&i915->gt, false);
+
  out_unlock:
        intel_uncore_forcewake_put(&i915->uncore, FORCEWAKE_ALL);
        mutex_unlock(&i915->drm.struct_mutex);
diff --git a/drivers/gpu/drm/i915/gt/intel_gt_types.h 
b/drivers/gpu/drm/i915/gt/intel_gt_types.h
index dc295c196d11..3039cef64b11 100644
--- a/drivers/gpu/drm/i915/gt/intel_gt_types.h
+++ b/drivers/gpu/drm/i915/gt/intel_gt_types.h
@@ -50,6 +50,7 @@ struct intel_gt {
        } timelines;
struct intel_wakeref wakeref;
+       atomic_t user_wakeref;
struct list_head closed_vma;
        spinlock_t closed_lock; /* guards the list of closed_vma */
diff --git a/drivers/gpu/drm/i915/i915_debugfs.c 
b/drivers/gpu/drm/i915/i915_debugfs.c
index 708855e051b5..f00c0dc4f57e 100644
--- a/drivers/gpu/drm/i915/i915_debugfs.c
+++ b/drivers/gpu/drm/i915/i915_debugfs.c
@@ -3988,13 +3988,12 @@ static int i915_sseu_status(struct seq_file *m, void 
*unused)
  static int i915_forcewake_open(struct inode *inode, struct file *file)
  {
        struct drm_i915_private *i915 = inode->i_private;
+       struct intel_gt *gt = &i915->gt;
- if (INTEL_GEN(i915) < 6)
-               return 0;
-
-       file->private_data =
-               (void *)(uintptr_t)intel_runtime_pm_get(&i915->runtime_pm);
-       intel_uncore_forcewake_user_get(&i915->uncore);
+       atomic_inc(&gt->user_wakeref);
+       intel_gt_pm_get(gt);
+       if (INTEL_GEN(i915) >= 6)
+               intel_uncore_forcewake_user_get(gt->uncore);
return 0;
  }
@@ -4002,13 +4001,12 @@ static int i915_forcewake_open(struct inode *inode, 
struct file *file)
  static int i915_forcewake_release(struct inode *inode, struct file *file)
  {
        struct drm_i915_private *i915 = inode->i_private;
+       struct intel_gt *gt = &i915->gt;
- if (INTEL_GEN(i915) < 6)
-               return 0;
-
-       intel_uncore_forcewake_user_put(&i915->uncore);
-       intel_runtime_pm_put(&i915->runtime_pm,
-                            (intel_wakeref_t)(uintptr_t)file->private_data);
+       if (INTEL_GEN(i915) >= 6)
+               intel_uncore_forcewake_user_put(&i915->uncore);
+       intel_gt_pm_put(gt);
+       atomic_dec(&gt->user_wakeref);
return 0;
  }
diff --git a/drivers/gpu/drm/i915/i915_pmu.c b/drivers/gpu/drm/i915/i915_pmu.c
index 8e251e719390..a3d3d3e39c15 100644
--- a/drivers/gpu/drm/i915/i915_pmu.c
+++ b/drivers/gpu/drm/i915/i915_pmu.c
@@ -116,19 +116,51 @@ static bool pmu_needs_timer(struct i915_pmu *pmu, bool 
gpu_active)
        return enable;
  }
+static u64 __get_rc6(struct intel_gt *gt)
+{
+       struct drm_i915_private *i915 = gt->i915;
+       u64 val;
+
+       val = intel_rc6_residency_ns(i915,
+                                    IS_VALLEYVIEW(i915) ?
+                                    VLV_GT_RENDER_RC6 :
+                                    GEN6_GT_GFX_RC6);
+
+       if (HAS_RC6p(i915))
+               val += intel_rc6_residency_ns(i915, GEN6_GT_GFX_RC6p);
+
+       if (HAS_RC6pp(i915))
+               val += intel_rc6_residency_ns(i915, GEN6_GT_GFX_RC6pp);
+
+       return val;
+}
+
  void i915_pmu_gt_parked(struct drm_i915_private *i915)
  {
        struct i915_pmu *pmu = &i915->pmu;
+       u64 val;
if (!pmu->base.event_init)
                return;
spin_lock_irq(&pmu->lock);
+
+       val = 0;
+       if (pmu->sample[__I915_SAMPLE_RC6].cur)
+               val = __get_rc6(&i915->gt);
+
+       if (val >= pmu->sample[__I915_SAMPLE_RC6_ESTIMATED].cur) {
+               pmu->sample[__I915_SAMPLE_RC6_ESTIMATED].cur = 0;
+               pmu->sample[__I915_SAMPLE_RC6].cur = val;
+       }
+       pmu->sleep_last = ktime_get();
+
        /*
         * Signal sampling timer to stop if only engine events are enabled and
         * GPU went idle.
         */
        pmu->timer_enabled = pmu_needs_timer(pmu, false);
+
        spin_unlock_irq(&pmu->lock);
  }
@@ -143,6 +175,11 @@ static void __i915_pmu_maybe_start_timer(struct i915_pmu *pmu)
        }
  }
+static inline s64 ktime_since(const ktime_t kt)
+{
+       return ktime_to_ns(ktime_sub(ktime_get(), kt));
+}
+
  void i915_pmu_gt_unparked(struct drm_i915_private *i915)
  {
        struct i915_pmu *pmu = &i915->pmu;
@@ -151,10 +188,22 @@ void i915_pmu_gt_unparked(struct drm_i915_private *i915)
                return;
spin_lock_irq(&pmu->lock);
+
        /*
         * Re-enable sampling timer when GPU goes active.
         */
        __i915_pmu_maybe_start_timer(pmu);
+
+       /* Estimate how long we slept and accumulate that into rc6 counters */
+       if (pmu->sample[__I915_SAMPLE_RC6].cur) {
+               u64 val;
+
+               val = ktime_since(pmu->sleep_last);
+               val += pmu->sample[__I915_SAMPLE_RC6].cur;
+
+               pmu->sample[__I915_SAMPLE_RC6_ESTIMATED].cur = val;
+       }
+
        spin_unlock_irq(&pmu->lock);
  }
@@ -426,39 +475,18 @@ static int i915_pmu_event_init(struct perf_event *event)
        return 0;
  }
-static u64 __get_rc6(struct intel_gt *gt)
-{
-       struct drm_i915_private *i915 = gt->i915;
-       u64 val;
-
-       val = intel_rc6_residency_ns(i915,
-                                    IS_VALLEYVIEW(i915) ?
-                                    VLV_GT_RENDER_RC6 :
-                                    GEN6_GT_GFX_RC6);
-
-       if (HAS_RC6p(i915))
-               val += intel_rc6_residency_ns(i915, GEN6_GT_GFX_RC6p);
-
-       if (HAS_RC6pp(i915))
-               val += intel_rc6_residency_ns(i915, GEN6_GT_GFX_RC6pp);
-
-       return val;
-}
-
  static u64 get_rc6(struct intel_gt *gt)
  {
-#if IS_ENABLED(CONFIG_PM)
        struct drm_i915_private *i915 = gt->i915;
-       struct intel_runtime_pm *rpm = &i915->runtime_pm;
        struct i915_pmu *pmu = &i915->pmu;
-       intel_wakeref_t wakeref;
        unsigned long flags;
        u64 val;
- wakeref = intel_runtime_pm_get_if_in_use(rpm);
-       if (wakeref) {
+       spin_lock_irqsave(&pmu->lock, flags);
+
+       if (intel_gt_pm_get_if_awake(gt)) {
                val = __get_rc6(gt);
-               intel_runtime_pm_put(rpm, wakeref);
+               intel_gt_pm_put(gt);
/*
                 * If we are coming back from being runtime suspended we must
@@ -466,19 +494,13 @@ static u64 get_rc6(struct intel_gt *gt)
                 * previously.
                 */
- spin_lock_irqsave(&pmu->lock, flags);
-
                if (val >= pmu->sample[__I915_SAMPLE_RC6_ESTIMATED].cur) {
                        pmu->sample[__I915_SAMPLE_RC6_ESTIMATED].cur = 0;
                        pmu->sample[__I915_SAMPLE_RC6].cur = val;
                } else {
                        val = pmu->sample[__I915_SAMPLE_RC6_ESTIMATED].cur;
                }
-
-               spin_unlock_irqrestore(&pmu->lock, flags);

For this branch pmu->lock is only needed over the estimation block, not over __get_rc6() and intel_gt_pm_get_if_awake(). But I agree it's more efficient to do it like this to avoid multiple irq-off-on transitions via intel_rc6_residency_ns. I wanted to suggest local_irq_disable and separate spin_(un)lock's on both if branches for more self-documenting , less confusion, but then single call also has it's benefits.

        } else {
-               struct device *kdev = rpm->kdev;
-
                /*
                 * We are runtime suspended.
                 *
@@ -486,42 +508,16 @@ static u64 get_rc6(struct intel_gt *gt)
                 * on top of the last known real value, as the approximated RC6
                 * counter value.
                 */
-               spin_lock_irqsave(&pmu->lock, flags);
- /*
-                * After the above branch intel_runtime_pm_get_if_in_use failed
-                * to get the runtime PM reference we cannot assume we are in
-                * runtime suspend since we can either: a) race with coming out
-                * of it before we took the power.lock, or b) there are other
-                * states than suspended which can bring us here.
-                *
-                * We need to double-check that we are indeed currently runtime
-                * suspended and if not we cannot do better than report the last
-                * known RC6 value.
-                */
-               if (pm_runtime_status_suspended(kdev)) {
-                       val = pm_runtime_suspended_time(kdev);
+               val = ktime_since(pmu->sleep_last);
+               val += pmu->sample[__I915_SAMPLE_RC6].cur;
- if (!pmu->sample[__I915_SAMPLE_RC6_ESTIMATED].cur)
-                               pmu->suspended_time_last = val;
-
-                       val -= pmu->suspended_time_last;
-                       val += pmu->sample[__I915_SAMPLE_RC6].cur;
-
-                       pmu->sample[__I915_SAMPLE_RC6_ESTIMATED].cur = val;
-               } else if (pmu->sample[__I915_SAMPLE_RC6_ESTIMATED].cur) {
-                       val = pmu->sample[__I915_SAMPLE_RC6_ESTIMATED].cur;
-               } else {
-                       val = pmu->sample[__I915_SAMPLE_RC6].cur;
-               }
-
-               spin_unlock_irqrestore(&pmu->lock, flags);
+               pmu->sample[__I915_SAMPLE_RC6_ESTIMATED].cur = val;
        }
+ spin_unlock_irqrestore(&pmu->lock, flags);
+
        return val;
-#else
-       return __get_rc6(gt);
-#endif

Don't we end up doing the irqsave spinlock needlessly when !CONFIG_PM?

  }
static u64 __i915_pmu_event_read(struct perf_event *event)
diff --git a/drivers/gpu/drm/i915/i915_pmu.h b/drivers/gpu/drm/i915/i915_pmu.h
index 4fc4f2478301..067dbbf3bdff 100644
--- a/drivers/gpu/drm/i915/i915_pmu.h
+++ b/drivers/gpu/drm/i915/i915_pmu.h
@@ -97,9 +97,9 @@ struct i915_pmu {
         */
        struct i915_pmu_sample sample[__I915_NUM_PMU_SAMPLERS];
        /**
-        * @suspended_time_last: Cached suspend time from PM core.
+        * @sleep_last: Last time GT parked for RC6 estimation.
         */
-       u64 suspended_time_last;
+       ktime_t sleep_last;
        /**
         * @i915_attr: Memory block holding device attributes.
         */


Regards,

Tvrtko
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