From feff0dc6cdc527f8a6fd170d8de7966f56890fc0 Mon Sep 17 00:00:00 2001 From: Tvrtko Ursulin Date: Tue, 21 Nov 2017 18:18:46 +0000 Subject: [PATCH] drm/i915/pmu: Suspend sampling when GPU is idle If only a subset of events is enabled we can afford to suspend the sampling timer when the GPU is idle and so save some cycles and power. v2: Rebase and limit timer even more. v3: Rebase. v4: Rebase. v5: Skip action if perf PMU failed to register. v6: Checkpatch cleanup. v7: * Add a common helper to start the timer if needed. (Chris Wilson) * Add comment explaining bitwise logic in pmu_needs_timer. v8: Fix some comments styles. (Chris Wilson) v9: Rebase. v10: Move function declarations to i915_pmu.h. v11: Rename functions to i915_pmu_gt_(un)parked. (Chris Wilson) Signed-off-by: Tvrtko Ursulin Reviewed-by: Chris Wilson Link: https://patchwork.freedesktop.org/patch/msgid/20171121181852.16128-3-tvrtko.ursulin@linux.intel.com --- drivers/gpu/drm/i915/i915_gem.c | 1 + drivers/gpu/drm/i915/i915_gem_request.c | 1 + drivers/gpu/drm/i915/i915_pmu.c | 88 ++++++++++++++++++++++--- drivers/gpu/drm/i915/i915_pmu.h | 8 +++ 4 files changed, 88 insertions(+), 10 deletions(-) diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c index 792e6dc7e19b..21ca680e9e63 100644 --- a/drivers/gpu/drm/i915/i915_gem.c +++ b/drivers/gpu/drm/i915/i915_gem.c @@ -3372,6 +3372,7 @@ i915_gem_idle_work_handler(struct work_struct *work) intel_engines_park(dev_priv); i915_gem_timelines_mark_idle(dev_priv); + i915_pmu_gt_parked(dev_priv); GEM_BUG_ON(!dev_priv->gt.awake); dev_priv->gt.awake = false; diff --git a/drivers/gpu/drm/i915/i915_gem_request.c b/drivers/gpu/drm/i915/i915_gem_request.c index 86e2346357cf..7325469ce754 100644 --- a/drivers/gpu/drm/i915/i915_gem_request.c +++ b/drivers/gpu/drm/i915/i915_gem_request.c @@ -258,6 +258,7 @@ static void mark_busy(struct drm_i915_private *i915) i915_update_gfx_val(i915); if (INTEL_GEN(i915) >= 6) gen6_rps_busy(i915); + i915_pmu_gt_unparked(i915); intel_engines_unpark(i915); diff --git a/drivers/gpu/drm/i915/i915_pmu.c b/drivers/gpu/drm/i915/i915_pmu.c index 01b5ee67c1bf..fb95f0ac30ea 100644 --- a/drivers/gpu/drm/i915/i915_pmu.c +++ b/drivers/gpu/drm/i915/i915_pmu.c @@ -90,6 +90,75 @@ static unsigned int event_enabled_bit(struct perf_event *event) return config_enabled_bit(event->attr.config); } +static bool pmu_needs_timer(struct drm_i915_private *i915, bool gpu_active) +{ + u64 enable; + + /* + * Only some counters need the sampling timer. + * + * We start with a bitmask of all currently enabled events. + */ + enable = i915->pmu.enable; + + /* + * Mask out all the ones which do not need the timer, or in + * other words keep all the ones that could need the timer. + */ + enable &= config_enabled_mask(I915_PMU_ACTUAL_FREQUENCY) | + config_enabled_mask(I915_PMU_REQUESTED_FREQUENCY) | + ENGINE_SAMPLE_MASK; + + /* + * When the GPU is idle per-engine counters do not need to be + * running so clear those bits out. + */ + if (!gpu_active) + enable &= ~ENGINE_SAMPLE_MASK; + + /* + * If some bits remain it means we need the sampling timer running. + */ + return enable; +} + +void i915_pmu_gt_parked(struct drm_i915_private *i915) +{ + if (!i915->pmu.base.event_init) + return; + + spin_lock_irq(&i915->pmu.lock); + /* + * Signal sampling timer to stop if only engine events are enabled and + * GPU went idle. + */ + i915->pmu.timer_enabled = pmu_needs_timer(i915, false); + spin_unlock_irq(&i915->pmu.lock); +} + +static void __i915_pmu_maybe_start_timer(struct drm_i915_private *i915) +{ + if (!i915->pmu.timer_enabled && pmu_needs_timer(i915, true)) { + i915->pmu.timer_enabled = true; + hrtimer_start_range_ns(&i915->pmu.timer, + ns_to_ktime(PERIOD), 0, + HRTIMER_MODE_REL_PINNED); + } +} + +void i915_pmu_gt_unparked(struct drm_i915_private *i915) +{ + if (!i915->pmu.base.event_init) + return; + + spin_lock_irq(&i915->pmu.lock); + /* + * Re-enable sampling timer when GPU goes active. + */ + __i915_pmu_maybe_start_timer(i915); + spin_unlock_irq(&i915->pmu.lock); +} + static bool grab_forcewake(struct drm_i915_private *i915, bool fw) { if (!fw) @@ -187,7 +256,7 @@ static enum hrtimer_restart i915_sample(struct hrtimer *hrtimer) struct drm_i915_private *i915 = container_of(hrtimer, struct drm_i915_private, pmu.timer); - if (i915->pmu.enable == 0) + if (!READ_ONCE(i915->pmu.timer_enabled)) return HRTIMER_NORESTART; engines_sample(i915); @@ -339,14 +408,6 @@ static void i915_pmu_enable(struct perf_event *event) spin_lock_irqsave(&i915->pmu.lock, flags); - /* - * Start the sampling timer when enabling the first event. - */ - if (i915->pmu.enable == 0) - hrtimer_start_range_ns(&i915->pmu.timer, - ns_to_ktime(PERIOD), 0, - HRTIMER_MODE_REL_PINNED); - /* * Update the bitmask of enabled events and increment * the event reference counter. @@ -356,6 +417,11 @@ static void i915_pmu_enable(struct perf_event *event) i915->pmu.enable |= BIT_ULL(bit); i915->pmu.enable_count[bit]++; + /* + * Start the sampling timer if needed and not already enabled. + */ + __i915_pmu_maybe_start_timer(i915); + /* * For per-engine events the bitmask and reference counting * is stored per engine. @@ -418,8 +484,10 @@ static void i915_pmu_disable(struct perf_event *event) * Decrement the reference count and clear the enabled * bitmask when the last listener on an event goes away. */ - if (--i915->pmu.enable_count[bit] == 0) + if (--i915->pmu.enable_count[bit] == 0) { i915->pmu.enable &= ~BIT_ULL(bit); + i915->pmu.timer_enabled &= pmu_needs_timer(i915, true); + } spin_unlock_irqrestore(&i915->pmu.lock, flags); } diff --git a/drivers/gpu/drm/i915/i915_pmu.h b/drivers/gpu/drm/i915/i915_pmu.h index 1ac8b2e34607..e209783a4c5f 100644 --- a/drivers/gpu/drm/i915/i915_pmu.h +++ b/drivers/gpu/drm/i915/i915_pmu.h @@ -82,6 +82,10 @@ struct i915_pmu { * are using the PMU API. */ unsigned int enable_count[I915_PMU_MASK_BITS]; + /** + * @timer_enabled: Should the internal sampling timer be running. + */ + bool timer_enabled; /** * @sample: Current and previous (raw) counters for sampling events. * @@ -96,9 +100,13 @@ struct i915_pmu { #ifdef CONFIG_PERF_EVENTS void i915_pmu_register(struct drm_i915_private *i915); void i915_pmu_unregister(struct drm_i915_private *i915); +void i915_pmu_gt_parked(struct drm_i915_private *i915); +void i915_pmu_gt_unparked(struct drm_i915_private *i915); #else static inline void i915_pmu_register(struct drm_i915_private *i915) {} static inline void i915_pmu_unregister(struct drm_i915_private *i915) {} +static inline void i915_pmu_gt_parked(struct drm_i915_private *i915) {} +static inline void i915_pmu_gt_unparked(struct drm_i915_private *i915) {} #endif #endif -- 2.30.2