| /* |
| * Copyright (C) 2015 The Android Open Source Project |
| * |
| * Licensed under the Apache License, Version 2.0 (the "License"); |
| * you may not use this file except in compliance with the License. |
| * You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| package com.android.internal.os; |
| |
| import android.text.TextUtils; |
| import android.util.Slog; |
| |
| import java.io.BufferedReader; |
| import java.io.FileReader; |
| import java.io.IOException; |
| import java.util.Arrays; |
| |
| /** |
| * Reads CPU time of a specific core spent at various frequencies and provides a delta from the |
| * last call to {@link #readDelta}. Each line in the proc file has the format: |
| * |
| * freq time |
| * |
| * where time is measured in 1/100 seconds. |
| */ |
| public class KernelCpuSpeedReader { |
| private static final String TAG = "KernelCpuSpeedReader"; |
| |
| private final String mProcFile; |
| private final long[] mLastSpeedTimes; |
| private final long[] mDeltaSpeedTimes; |
| |
| /** |
| * @param cpuNumber The cpu (cpu0, cpu1, etc) whose state to read. |
| */ |
| public KernelCpuSpeedReader(int cpuNumber, int numSpeedSteps) { |
| mProcFile = String.format("/sys/devices/system/cpu/cpu%d/cpufreq/stats/time_in_state", |
| cpuNumber); |
| mLastSpeedTimes = new long[numSpeedSteps]; |
| mDeltaSpeedTimes = new long[numSpeedSteps]; |
| } |
| |
| /** |
| * The returned array is modified in subsequent calls to {@link #readDelta}. |
| * @return The time (in milliseconds) spent at different cpu speeds since the last call to |
| * {@link #readDelta}. |
| */ |
| public long[] readDelta() { |
| try (BufferedReader reader = new BufferedReader(new FileReader(mProcFile))) { |
| TextUtils.SimpleStringSplitter splitter = new TextUtils.SimpleStringSplitter(' '); |
| String line; |
| int speedIndex = 0; |
| while (speedIndex < mLastSpeedTimes.length && (line = reader.readLine()) != null) { |
| splitter.setString(line); |
| Long.parseLong(splitter.next()); |
| |
| // The proc file reports time in 1/100 sec, so convert to milliseconds. |
| long time = Long.parseLong(splitter.next()) * 10; |
| if (time < mLastSpeedTimes[speedIndex]) { |
| // The stats reset when the cpu hotplugged. That means that the time |
| // we read is offset from 0, so the time is the delta. |
| mDeltaSpeedTimes[speedIndex] = time; |
| } else { |
| mDeltaSpeedTimes[speedIndex] = time - mLastSpeedTimes[speedIndex]; |
| } |
| mLastSpeedTimes[speedIndex] = time; |
| speedIndex++; |
| } |
| } catch (IOException e) { |
| Slog.e(TAG, "Failed to read cpu-freq: " + e.getMessage()); |
| Arrays.fill(mDeltaSpeedTimes, 0); |
| } |
| return mDeltaSpeedTimes; |
| } |
| } |