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df6a420535
Avoid rc6 counter going backward in close to 0% RC6 scenarios like:
15.005477996 114,246,613 ns i915/rc6-residency/
16.005876662 667,657 ns i915/rc6-residency/
17.006131417 7,286 ns i915/rc6-residency/
18.006615031 18,446,744,073,708,914,688 ns i915/rc6-residency/
19.007158361 18,446,744,073,709,447,168 ns i915/rc6-residency/
20.007806498 0 ns i915/rc6-residency/
21.008227495 1,440,403 ns i915/rc6-residency/
There are two aspects to this fix.
First is not assuming rc6 value zero means GT is asleep since that can
also mean GPU is fully busy and we do not want to enter the estimation
path in that case.
Second is ensuring monotonicity on the estimation path itself. I suspect
what is happening is with extremely rapid park/unpark cycles we get no
updates on the real rc6 and therefore have to careful not to
unconditionally trust use last known real rc6 when creating a new
estimation.
v2:
* Simplify logic by not tracking the estimate but last reported value.
Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Fixes: 16ffe73c18 ("drm/i915/pmu: Use GT parked for estimating RC6 while asleep")
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk> # v1
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Link: https://patchwork.freedesktop.org/patch/msgid/20191217142057.1000-1-tvrtko.ursulin@linux.intel.com
130 lines
3.2 KiB
C
130 lines
3.2 KiB
C
/*
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* SPDX-License-Identifier: MIT
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*
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* Copyright © 2017-2018 Intel Corporation
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*/
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#ifndef __I915_PMU_H__
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#define __I915_PMU_H__
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#include <linux/hrtimer.h>
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#include <linux/perf_event.h>
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#include <linux/spinlock_types.h>
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#include <drm/i915_drm.h>
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struct drm_i915_private;
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enum {
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__I915_SAMPLE_FREQ_ACT = 0,
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__I915_SAMPLE_FREQ_REQ,
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__I915_SAMPLE_RC6,
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__I915_SAMPLE_RC6_LAST_REPORTED,
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__I915_NUM_PMU_SAMPLERS
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};
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/**
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* How many different events we track in the global PMU mask.
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*
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* It is also used to know to needed number of event reference counters.
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*/
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#define I915_PMU_MASK_BITS \
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((1 << I915_PMU_SAMPLE_BITS) + \
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(I915_PMU_LAST + 1 - __I915_PMU_OTHER(0)))
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#define I915_ENGINE_SAMPLE_COUNT (I915_SAMPLE_SEMA + 1)
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struct i915_pmu_sample {
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u64 cur;
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};
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struct i915_pmu {
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/**
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* @node: List node for CPU hotplug handling.
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*/
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struct hlist_node node;
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/**
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* @base: PMU base.
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*/
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struct pmu base;
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/**
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* @name: Name as registered with perf core.
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*/
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const char *name;
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/**
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* @lock: Lock protecting enable mask and ref count handling.
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*/
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spinlock_t lock;
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/**
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* @timer: Timer for internal i915 PMU sampling.
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*/
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struct hrtimer timer;
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/**
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* @enable: Bitmask of all currently enabled events.
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*
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* Bits are derived from uAPI event numbers in a way that low 16 bits
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* correspond to engine event _sample_ _type_ (I915_SAMPLE_QUEUED is
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* bit 0), and higher bits correspond to other events (for instance
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* I915_PMU_ACTUAL_FREQUENCY is bit 16 etc).
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*
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* In other words, low 16 bits are not per engine but per engine
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* sampler type, while the upper bits are directly mapped to other
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* event types.
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*/
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u64 enable;
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/**
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* @timer_last:
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*
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* Timestmap of the previous timer invocation.
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*/
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ktime_t timer_last;
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/**
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* @enable_count: Reference counts for the enabled events.
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*
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* Array indices are mapped in the same way as bits in the @enable field
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* and they are used to control sampling on/off when multiple clients
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* are using the PMU API.
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*/
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unsigned int enable_count[I915_PMU_MASK_BITS];
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/**
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* @timer_enabled: Should the internal sampling timer be running.
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*/
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bool timer_enabled;
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/**
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* @sample: Current and previous (raw) counters for sampling events.
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*
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* These counters are updated from the i915 PMU sampling timer.
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*
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* Only global counters are held here, while the per-engine ones are in
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* struct intel_engine_cs.
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*/
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struct i915_pmu_sample sample[__I915_NUM_PMU_SAMPLERS];
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/**
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* @sleep_last: Last time GT parked for RC6 estimation.
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*/
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ktime_t sleep_last;
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/**
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* @i915_attr: Memory block holding device attributes.
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*/
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void *i915_attr;
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/**
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* @pmu_attr: Memory block holding device attributes.
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*/
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void *pmu_attr;
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};
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#ifdef CONFIG_PERF_EVENTS
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void i915_pmu_register(struct drm_i915_private *i915);
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void i915_pmu_unregister(struct drm_i915_private *i915);
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void i915_pmu_gt_parked(struct drm_i915_private *i915);
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void i915_pmu_gt_unparked(struct drm_i915_private *i915);
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#else
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static inline void i915_pmu_register(struct drm_i915_private *i915) {}
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static inline void i915_pmu_unregister(struct drm_i915_private *i915) {}
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static inline void i915_pmu_gt_parked(struct drm_i915_private *i915) {}
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static inline void i915_pmu_gt_unparked(struct drm_i915_private *i915) {}
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#endif
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#endif
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