1 /* 2 * Copyright 2019 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17 #pragma once 18 19 #include <android-base/thread_annotations.h> 20 #include <mutex> 21 #include <unordered_map> 22 #include <vector> 23 #include "SchedulerUtils.h" 24 #include "VSyncTracker.h" 25 26 namespace android::scheduler { 27 28 class VSyncPredictor : public VSyncTracker { 29 public: 30 /* 31 * \param [in] idealPeriod The initial ideal period to use. 32 * \param [in] historySize The internal amount of entries to store in the model. 33 * \param [in] minimumSamplesForPrediction The minimum number of samples to collect before 34 * predicting. \param [in] outlierTolerancePercent a number 0 to 100 that will be used to filter 35 * samples that fall outlierTolerancePercent from an anticipated vsync event. 36 */ 37 VSyncPredictor(nsecs_t idealPeriod, size_t historySize, size_t minimumSamplesForPrediction, 38 uint32_t outlierTolerancePercent); 39 ~VSyncPredictor(); 40 41 bool addVsyncTimestamp(nsecs_t timestamp) final; 42 nsecs_t nextAnticipatedVSyncTimeFrom(nsecs_t timePoint) const final; 43 nsecs_t currentPeriod() const final; 44 void resetModel() final; 45 46 /* 47 * Inform the model that the period is anticipated to change to a new value. 48 * model will use the period parameter to predict vsync events until enough 49 * timestamps with the new period have been collected. 50 * 51 * \param [in] period The new period that should be used. 52 */ 53 void setPeriod(nsecs_t period) final; 54 55 /* Query if the model is in need of more samples to make a prediction. 56 * \return True, if model would benefit from more samples, False if not. 57 */ 58 bool needsMoreSamples() const final; 59 60 std::tuple<nsecs_t /* slope */, nsecs_t /* intercept */> getVSyncPredictionModel() const; 61 62 void dump(std::string& result) const final; 63 64 private: 65 VSyncPredictor(VSyncPredictor const&) = delete; 66 VSyncPredictor& operator=(VSyncPredictor const&) = delete; 67 void clearTimestamps() REQUIRES(mMutex); 68 69 inline void traceInt64If(const char* name, int64_t value) const; 70 bool const mTraceOn; 71 72 size_t const kHistorySize; 73 size_t const kMinimumSamplesForPrediction; 74 size_t const kOutlierTolerancePercent; 75 76 std::mutex mutable mMutex; 77 size_t next(int i) const REQUIRES(mMutex); 78 bool validate(nsecs_t timestamp) const REQUIRES(mMutex); 79 std::tuple<nsecs_t, nsecs_t> getVSyncPredictionModel(std::lock_guard<std::mutex> const&) const 80 REQUIRES(mMutex); 81 82 nsecs_t mIdealPeriod GUARDED_BY(mMutex); 83 std::optional<nsecs_t> mKnownTimestamp GUARDED_BY(mMutex); 84 85 std::unordered_map<nsecs_t, std::tuple<nsecs_t, nsecs_t>> mutable mRateMap GUARDED_BY(mMutex); 86 87 int mLastTimestampIndex GUARDED_BY(mMutex) = 0; 88 std::vector<nsecs_t> mTimestamps GUARDED_BY(mMutex); 89 }; 90 91 } // namespace android::scheduler 92