1 /* 2 * Copyright (C) 2015 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 package com.android.internal.os; 17 18 import android.annotation.Nullable; 19 import android.os.SystemClock; 20 import android.text.TextUtils; 21 import android.util.Slog; 22 import android.util.SparseLongArray; 23 import android.util.TimeUtils; 24 25 import java.io.BufferedReader; 26 import java.io.FileReader; 27 import java.io.FileWriter; 28 import java.io.IOException; 29 30 /** 31 * Reads /proc/uid_cputime/show_uid_stat which has the line format: 32 * 33 * uid: user_time_micro_seconds system_time_micro_seconds power_in_milli-amp-micro_seconds 34 * 35 * This provides the time a UID's processes spent executing in user-space and kernel-space. 36 * The file contains a monotonically increasing count of time for a single boot. This class 37 * maintains the previous results of a call to {@link #readDelta} in order to provide a proper 38 * delta. 39 */ 40 public class KernelUidCpuTimeReader { 41 private static final String TAG = "KernelUidCpuTimeReader"; 42 private static final String sProcFile = "/proc/uid_cputime/show_uid_stat"; 43 private static final String sRemoveUidProcFile = "/proc/uid_cputime/remove_uid_range"; 44 45 /** 46 * Callback interface for processing each line of the proc file. 47 */ 48 public interface Callback { 49 /** 50 * @param uid UID of the app 51 * @param userTimeUs time spent executing in user space in microseconds 52 * @param systemTimeUs time spent executing in kernel space in microseconds 53 */ onUidCpuTime(int uid, long userTimeUs, long systemTimeUs)54 void onUidCpuTime(int uid, long userTimeUs, long systemTimeUs); 55 } 56 57 private SparseLongArray mLastUserTimeUs = new SparseLongArray(); 58 private SparseLongArray mLastSystemTimeUs = new SparseLongArray(); 59 private long mLastTimeReadUs = 0; 60 61 /** 62 * Reads the proc file, calling into the callback with a delta of time for each UID. 63 * @param callback The callback to invoke for each line of the proc file. If null, 64 * the data is consumed and subsequent calls to readDelta will provide 65 * a fresh delta. 66 */ readDelta(@ullable Callback callback)67 public void readDelta(@Nullable Callback callback) { 68 long nowUs = SystemClock.elapsedRealtime() * 1000; 69 try (BufferedReader reader = new BufferedReader(new FileReader(sProcFile))) { 70 TextUtils.SimpleStringSplitter splitter = new TextUtils.SimpleStringSplitter(' '); 71 String line; 72 while ((line = reader.readLine()) != null) { 73 splitter.setString(line); 74 final String uidStr = splitter.next(); 75 final int uid = Integer.parseInt(uidStr.substring(0, uidStr.length() - 1), 10); 76 final long userTimeUs = Long.parseLong(splitter.next(), 10); 77 final long systemTimeUs = Long.parseLong(splitter.next(), 10); 78 79 // Only report if there is a callback and if this is not the first read. 80 if (callback != null && mLastTimeReadUs != 0) { 81 long userTimeDeltaUs = userTimeUs; 82 long systemTimeDeltaUs = systemTimeUs; 83 int index = mLastUserTimeUs.indexOfKey(uid); 84 if (index >= 0) { 85 userTimeDeltaUs -= mLastUserTimeUs.valueAt(index); 86 systemTimeDeltaUs -= mLastSystemTimeUs.valueAt(index); 87 88 final long timeDiffUs = nowUs - mLastTimeReadUs; 89 if (userTimeDeltaUs < 0 || systemTimeDeltaUs < 0) { 90 StringBuilder sb = new StringBuilder("Malformed cpu data for UID="); 91 sb.append(uid).append("!\n"); 92 sb.append("Time between reads: "); 93 TimeUtils.formatDuration(timeDiffUs / 1000, sb); 94 sb.append("\n"); 95 sb.append("Previous times: u="); 96 TimeUtils.formatDuration(mLastUserTimeUs.valueAt(index) / 1000, sb); 97 sb.append(" s="); 98 TimeUtils.formatDuration(mLastSystemTimeUs.valueAt(index) / 1000, sb); 99 100 sb.append("\nCurrent times: u="); 101 TimeUtils.formatDuration(userTimeUs / 1000, sb); 102 sb.append(" s="); 103 TimeUtils.formatDuration(systemTimeUs / 1000, sb); 104 sb.append("\nDelta: u="); 105 TimeUtils.formatDuration(userTimeDeltaUs / 1000, sb); 106 sb.append(" s="); 107 TimeUtils.formatDuration(systemTimeDeltaUs / 1000, sb); 108 Slog.e(TAG, sb.toString()); 109 110 userTimeDeltaUs = 0; 111 systemTimeDeltaUs = 0; 112 } 113 } 114 115 if (userTimeDeltaUs != 0 || systemTimeDeltaUs != 0) { 116 callback.onUidCpuTime(uid, userTimeDeltaUs, systemTimeDeltaUs); 117 } 118 } 119 mLastUserTimeUs.put(uid, userTimeUs); 120 mLastSystemTimeUs.put(uid, systemTimeUs); 121 } 122 } catch (IOException e) { 123 Slog.e(TAG, "Failed to read uid_cputime: " + e.getMessage()); 124 } 125 mLastTimeReadUs = nowUs; 126 } 127 128 /** 129 * Removes the UID from the kernel module and from internal accounting data. 130 * @param uid The UID to remove. 131 */ removeUid(int uid)132 public void removeUid(int uid) { 133 int index = mLastUserTimeUs.indexOfKey(uid); 134 if (index >= 0) { 135 mLastUserTimeUs.removeAt(index); 136 mLastSystemTimeUs.removeAt(index); 137 } 138 139 try (FileWriter writer = new FileWriter(sRemoveUidProcFile)) { 140 writer.write(Integer.toString(uid) + "-" + Integer.toString(uid)); 141 writer.flush(); 142 } catch (IOException e) { 143 Slog.e(TAG, "failed to remove uid from uid_cputime module", e); 144 } 145 } 146 } 147