| /* |
| * Copyright (C) 2018 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.annotation.Nullable; |
| import android.os.Process; |
| import android.util.Slog; |
| |
| import com.android.internal.annotations.VisibleForTesting; |
| import com.android.internal.util.ArrayUtils; |
| import com.android.internal.util.Preconditions; |
| |
| import java.io.IOException; |
| import java.nio.file.DirectoryStream; |
| import java.nio.file.Files; |
| import java.nio.file.Path; |
| import java.nio.file.Paths; |
| import java.util.ArrayList; |
| import java.util.Arrays; |
| import java.util.function.Predicate; |
| |
| /** |
| * Iterates over processes, and all threads owned by those processes, and return the CPU usage for |
| * each thread. The CPU usage statistics contain the amount of time spent in a frequency band. CPU |
| * usage is collected using {@link ProcTimeInStateReader}. |
| * |
| * <p>We only collect CPU data for processes and threads that are owned by certain UIDs. These UIDs |
| * are configured via {@link #setUidPredicate}. |
| * |
| * <p>Frequencies are bucketed together to reduce the amount of data created. This means that we |
| * return less frequencies than provided by {@link ProcTimeInStateReader}. The number of frequencies |
| * is configurable by {@link #setNumBuckets}. Frequencies are reported as the lowest frequency in |
| * that range. Frequencies are spread as evenly as possible across the buckets. The buckets do not |
| * cross over the little/big frequencies reported. |
| * |
| * <p>N.B.: In order to bucket across little/big frequencies correctly, we assume that the {@code |
| * time_in_state} file contains every little core frequency in ascending order, followed by every |
| * big core frequency in ascending order. This assumption might not hold for devices with different |
| * kernel implementations of the {@code time_in_state} file generation. |
| */ |
| public class KernelCpuThreadReader { |
| |
| private static final String TAG = "KernelCpuThreadReader"; |
| |
| private static final boolean DEBUG = false; |
| |
| /** |
| * The name of the file to read CPU statistics from, must be found in {@code |
| * /proc/$PID/task/$TID} |
| */ |
| private static final String CPU_STATISTICS_FILENAME = "time_in_state"; |
| |
| /** |
| * The name of the file to read process command line invocation from, must be found in {@code |
| * /proc/$PID/} |
| */ |
| private static final String PROCESS_NAME_FILENAME = "cmdline"; |
| |
| /** |
| * The name of the file to read thread name from, must be found in {@code /proc/$PID/task/$TID} |
| */ |
| private static final String THREAD_NAME_FILENAME = "comm"; |
| |
| /** Glob pattern for the process directory names under {@code proc} */ |
| private static final String PROCESS_DIRECTORY_FILTER = "[0-9]*"; |
| |
| /** Default process name when the name can't be read */ |
| private static final String DEFAULT_PROCESS_NAME = "unknown_process"; |
| |
| /** Default thread name when the name can't be read */ |
| private static final String DEFAULT_THREAD_NAME = "unknown_thread"; |
| |
| /** Default mount location of the {@code proc} filesystem */ |
| private static final Path DEFAULT_PROC_PATH = Paths.get("/proc"); |
| |
| /** The initial {@code time_in_state} file for {@link ProcTimeInStateReader} */ |
| private static final Path DEFAULT_INITIAL_TIME_IN_STATE_PATH = |
| DEFAULT_PROC_PATH.resolve("self/time_in_state"); |
| |
| /** Value returned when there was an error getting an integer ID value (e.g. PID, UID) */ |
| private static final int ID_ERROR = -1; |
| |
| /** |
| * When checking whether to report data for a thread, we check the UID of the thread's owner |
| * against this predicate |
| */ |
| private Predicate<Integer> mUidPredicate; |
| |
| /** Where the proc filesystem is mounted */ |
| private final Path mProcPath; |
| |
| /** |
| * Frequencies read from the {@code time_in_state} file. Read from {@link |
| * #mProcTimeInStateReader#getCpuFrequenciesKhz()} and cast to {@code int[]} |
| */ |
| private int[] mFrequenciesKhz; |
| |
| /** Used to read and parse {@code time_in_state} files */ |
| private final ProcTimeInStateReader mProcTimeInStateReader; |
| |
| /** Used to sort frequencies and usage times into buckets */ |
| private FrequencyBucketCreator mFrequencyBucketCreator; |
| |
| private final Injector mInjector; |
| |
| /** |
| * Create with a path where `proc` is mounted. Used primarily for testing |
| * |
| * @param procPath where `proc` is mounted (to find, see {@code mount | grep ^proc}) |
| * @param initialTimeInStatePath where the initial {@code time_in_state} file exists to define |
| * format |
| */ |
| @VisibleForTesting |
| public KernelCpuThreadReader( |
| int numBuckets, |
| Predicate<Integer> uidPredicate, |
| Path procPath, |
| Path initialTimeInStatePath, |
| Injector injector) |
| throws IOException { |
| mUidPredicate = uidPredicate; |
| mProcPath = procPath; |
| mProcTimeInStateReader = new ProcTimeInStateReader(initialTimeInStatePath); |
| mInjector = injector; |
| setNumBuckets(numBuckets); |
| } |
| |
| /** |
| * Create the reader and handle exceptions during creation |
| * |
| * @return the reader, null if an exception was thrown during creation |
| */ |
| @Nullable |
| public static KernelCpuThreadReader create(int numBuckets, Predicate<Integer> uidPredicate) { |
| try { |
| return new KernelCpuThreadReader( |
| numBuckets, |
| uidPredicate, |
| DEFAULT_PROC_PATH, |
| DEFAULT_INITIAL_TIME_IN_STATE_PATH, |
| new Injector()); |
| } catch (IOException e) { |
| Slog.e(TAG, "Failed to initialize KernelCpuThreadReader", e); |
| return null; |
| } |
| } |
| |
| /** |
| * Get the per-thread CPU usage of all processes belonging to a set of UIDs |
| * |
| * <p>This function will crawl through all process {@code proc} directories found by the pattern |
| * {@code /proc/[0-9]*}, and then check the UID using {@code /proc/$PID/status}. This takes |
| * approximately 500ms on a 2017 device. Therefore, this method can be computationally |
| * expensive, and should not be called more than once an hour. |
| * |
| * <p>Data is only collected for UIDs passing the predicate supplied in {@link |
| * #setUidPredicate}. |
| */ |
| @Nullable |
| public ArrayList<ProcessCpuUsage> getProcessCpuUsage() { |
| if (DEBUG) { |
| Slog.d(TAG, "Reading CPU thread usages for processes owned by UIDs"); |
| } |
| |
| final ArrayList<ProcessCpuUsage> processCpuUsages = new ArrayList<>(); |
| |
| try (DirectoryStream<Path> processPaths = |
| Files.newDirectoryStream(mProcPath, PROCESS_DIRECTORY_FILTER)) { |
| for (Path processPath : processPaths) { |
| final int processId = getProcessId(processPath); |
| final int uid = mInjector.getUidForPid(processId); |
| if (uid == ID_ERROR || processId == ID_ERROR) { |
| continue; |
| } |
| if (!mUidPredicate.test(uid)) { |
| continue; |
| } |
| |
| final ProcessCpuUsage processCpuUsage = |
| getProcessCpuUsage(processPath, processId, uid); |
| if (processCpuUsage != null) { |
| processCpuUsages.add(processCpuUsage); |
| } |
| } |
| } catch (IOException e) { |
| Slog.w(TAG, "Failed to iterate over process paths", e); |
| return null; |
| } |
| |
| if (processCpuUsages.isEmpty()) { |
| Slog.w(TAG, "Didn't successfully get any process CPU information for UIDs specified"); |
| return null; |
| } |
| |
| if (DEBUG) { |
| Slog.d(TAG, "Read usage for " + processCpuUsages.size() + " processes"); |
| } |
| |
| return processCpuUsages; |
| } |
| |
| /** |
| * Get the CPU frequencies that correspond to the times reported in {@link |
| * ThreadCpuUsage#usageTimesMillis} |
| */ |
| @Nullable |
| public int[] getCpuFrequenciesKhz() { |
| return mFrequenciesKhz; |
| } |
| |
| /** Set the number of frequency buckets to use */ |
| void setNumBuckets(int numBuckets) { |
| if (numBuckets < 1) { |
| Slog.w(TAG, "Number of buckets must be at least 1, but was " + numBuckets); |
| return; |
| } |
| // If `numBuckets` hasn't changed since the last set, do nothing |
| if (mFrequenciesKhz != null && mFrequenciesKhz.length == numBuckets) { |
| return; |
| } |
| mFrequencyBucketCreator = |
| new FrequencyBucketCreator(mProcTimeInStateReader.getFrequenciesKhz(), numBuckets); |
| mFrequenciesKhz = |
| mFrequencyBucketCreator.bucketFrequencies( |
| mProcTimeInStateReader.getFrequenciesKhz()); |
| } |
| |
| /** Set the UID predicate for {@link #getProcessCpuUsage} */ |
| void setUidPredicate(Predicate<Integer> uidPredicate) { |
| mUidPredicate = uidPredicate; |
| } |
| |
| /** |
| * Read all of the CPU usage statistics for each child thread of a process |
| * |
| * @param processPath the {@code /proc} path of the thread |
| * @param processId the ID of the process |
| * @param uid the ID of the user who owns the process |
| * @return process CPU usage containing usage of all child threads. Null if the process exited |
| * and its {@code proc} directory was removed while collecting information |
| */ |
| @Nullable |
| private ProcessCpuUsage getProcessCpuUsage(Path processPath, int processId, int uid) { |
| if (DEBUG) { |
| Slog.d( |
| TAG, |
| "Reading CPU thread usages with directory " |
| + processPath |
| + " process ID " |
| + processId |
| + " and user ID " |
| + uid); |
| } |
| |
| final Path allThreadsPath = processPath.resolve("task"); |
| final ArrayList<ThreadCpuUsage> threadCpuUsages = new ArrayList<>(); |
| try (DirectoryStream<Path> threadPaths = Files.newDirectoryStream(allThreadsPath)) { |
| for (Path threadDirectory : threadPaths) { |
| ThreadCpuUsage threadCpuUsage = getThreadCpuUsage(threadDirectory); |
| if (threadCpuUsage == null) { |
| continue; |
| } |
| threadCpuUsages.add(threadCpuUsage); |
| } |
| } catch (IOException e) { |
| // Expected when a process finishes |
| return null; |
| } |
| |
| // If we found no threads, then the process has exited while we were reading from it |
| if (threadCpuUsages.isEmpty()) { |
| return null; |
| } |
| if (DEBUG) { |
| Slog.d(TAG, "Read CPU usage of " + threadCpuUsages.size() + " threads"); |
| } |
| return new ProcessCpuUsage(processId, getProcessName(processPath), uid, threadCpuUsages); |
| } |
| |
| /** |
| * Get a thread's CPU usage |
| * |
| * @param threadDirectory the {@code /proc} directory of the thread |
| * @return thread CPU usage. Null if the thread exited and its {@code proc} directory was |
| * removed while collecting information |
| */ |
| @Nullable |
| private ThreadCpuUsage getThreadCpuUsage(Path threadDirectory) { |
| // Get the thread ID from the directory name |
| final int threadId; |
| try { |
| final String directoryName = threadDirectory.getFileName().toString(); |
| threadId = Integer.parseInt(directoryName); |
| } catch (NumberFormatException e) { |
| Slog.w(TAG, "Failed to parse thread ID when iterating over /proc/*/task", e); |
| return null; |
| } |
| |
| // Get the thread name from the thread directory |
| final String threadName = getThreadName(threadDirectory); |
| |
| // Get the CPU statistics from the directory |
| final Path threadCpuStatPath = threadDirectory.resolve(CPU_STATISTICS_FILENAME); |
| final long[] cpuUsagesLong = mProcTimeInStateReader.getUsageTimesMillis(threadCpuStatPath); |
| if (cpuUsagesLong == null) { |
| return null; |
| } |
| int[] cpuUsages = mFrequencyBucketCreator.bucketValues(cpuUsagesLong); |
| |
| return new ThreadCpuUsage(threadId, threadName, cpuUsages); |
| } |
| |
| /** Get the command used to start a process */ |
| private String getProcessName(Path processPath) { |
| final Path processNamePath = processPath.resolve(PROCESS_NAME_FILENAME); |
| |
| final String processName = ProcStatsUtil.readSingleLineProcFile(processNamePath.toString()); |
| if (processName != null) { |
| return processName; |
| } |
| return DEFAULT_PROCESS_NAME; |
| } |
| |
| /** Get the name of a thread, given the {@code /proc} path of the thread */ |
| private String getThreadName(Path threadPath) { |
| final Path threadNamePath = threadPath.resolve(THREAD_NAME_FILENAME); |
| final String threadName = ProcStatsUtil.readNullSeparatedFile(threadNamePath.toString()); |
| if (threadName == null) { |
| return DEFAULT_THREAD_NAME; |
| } |
| return threadName; |
| } |
| |
| /** |
| * Get the ID of a process from its path |
| * |
| * @param processPath {@code proc} path of the process |
| * @return the ID, {@link #ID_ERROR} if the path could not be parsed |
| */ |
| private int getProcessId(Path processPath) { |
| String fileName = processPath.getFileName().toString(); |
| try { |
| return Integer.parseInt(fileName); |
| } catch (NumberFormatException e) { |
| Slog.w(TAG, "Failed to parse " + fileName + " as process ID", e); |
| return ID_ERROR; |
| } |
| } |
| |
| /** |
| * Quantizes a list of N frequencies into a list of M frequencies (where M<=N) |
| * |
| * <p>In order to reduce data sent from the device, we discard precise frequency information for |
| * an approximation. This is done by putting groups of adjacent frequencies into the same |
| * bucket, and then reporting that bucket under the minimum frequency in that bucket. |
| * |
| * <p>Many devices have multiple core clusters. We do not want to report frequencies from |
| * different clusters under the same bucket, so some complication arises. |
| * |
| * <p>Buckets are allocated evenly across all core clusters, i.e. they all have the same number |
| * of buckets regardless of how many frequencies they contain. This is done to reduce code |
| * complexity, and in practice the number of frequencies doesn't vary too much between core |
| * clusters. |
| * |
| * <p>If the number of buckets is not a factor of the number of frequencies, the remainder of |
| * the frequencies are placed into the last bucket. |
| * |
| * <p>It is possible to have less buckets than asked for, so any calling code can't assume that |
| * initializing with N buckets will use return N values. This happens in two scenarios: |
| * |
| * <ul> |
| * <li>There are less frequencies available than buckets asked for. |
| * <li>There are less frequencies in a core cluster than buckets allocated to that core |
| * cluster. |
| * </ul> |
| */ |
| @VisibleForTesting |
| public static class FrequencyBucketCreator { |
| private final int mNumFrequencies; |
| private final int mNumBuckets; |
| private final int[] mBucketStartIndices; |
| |
| @VisibleForTesting |
| public FrequencyBucketCreator(long[] frequencies, int targetNumBuckets) { |
| mNumFrequencies = frequencies.length; |
| int[] clusterStartIndices = getClusterStartIndices(frequencies); |
| mBucketStartIndices = |
| getBucketStartIndices(clusterStartIndices, targetNumBuckets, mNumFrequencies); |
| mNumBuckets = mBucketStartIndices.length; |
| } |
| |
| /** |
| * Put an array of values into buckets. This takes a {@code long[]} and returns {@code |
| * int[]} as everywhere this method is used will have to do the conversion anyway, so we |
| * save time by doing it here instead |
| * |
| * @param values the values to bucket |
| * @return the bucketed usage times |
| */ |
| @VisibleForTesting |
| public int[] bucketValues(long[] values) { |
| Preconditions.checkArgument(values.length == mNumFrequencies); |
| int[] buckets = new int[mNumBuckets]; |
| for (int bucketIdx = 0; bucketIdx < mNumBuckets; bucketIdx++) { |
| final int bucketStartIdx = getLowerBound(bucketIdx, mBucketStartIndices); |
| final int bucketEndIdx = |
| getUpperBound(bucketIdx, mBucketStartIndices, values.length); |
| for (int valuesIdx = bucketStartIdx; valuesIdx < bucketEndIdx; valuesIdx++) { |
| buckets[bucketIdx] += values[valuesIdx]; |
| } |
| } |
| return buckets; |
| } |
| |
| /** Get the minimum frequency in each bucket */ |
| @VisibleForTesting |
| public int[] bucketFrequencies(long[] frequencies) { |
| Preconditions.checkArgument(frequencies.length == mNumFrequencies); |
| int[] buckets = new int[mNumBuckets]; |
| for (int i = 0; i < buckets.length; i++) { |
| buckets[i] = (int) frequencies[mBucketStartIndices[i]]; |
| } |
| return buckets; |
| } |
| |
| /** |
| * Get the index in frequencies where each core cluster starts |
| * |
| * <p>The frequencies for each cluster are given in ascending order, appended to each other. |
| * This means that every time there is a decrease in frequencies (instead of increase) a new |
| * cluster has started. |
| */ |
| private static int[] getClusterStartIndices(long[] frequencies) { |
| ArrayList<Integer> indices = new ArrayList<>(); |
| indices.add(0); |
| for (int i = 0; i < frequencies.length - 1; i++) { |
| if (frequencies[i] >= frequencies[i + 1]) { |
| indices.add(i + 1); |
| } |
| } |
| return ArrayUtils.convertToIntArray(indices); |
| } |
| |
| /** Get the index in frequencies where each bucket starts */ |
| private static int[] getBucketStartIndices( |
| int[] clusterStartIndices, int targetNumBuckets, int numFrequencies) { |
| int numClusters = clusterStartIndices.length; |
| |
| // If we haven't got enough buckets for every cluster, we instead have one bucket per |
| // cluster, with the last bucket containing the remaining clusters |
| if (numClusters > targetNumBuckets) { |
| return Arrays.copyOfRange(clusterStartIndices, 0, targetNumBuckets); |
| } |
| |
| ArrayList<Integer> bucketStartIndices = new ArrayList<>(); |
| for (int clusterIdx = 0; clusterIdx < numClusters; clusterIdx++) { |
| final int clusterStartIdx = getLowerBound(clusterIdx, clusterStartIndices); |
| final int clusterEndIdx = |
| getUpperBound(clusterIdx, clusterStartIndices, numFrequencies); |
| |
| final int numBucketsInCluster; |
| if (clusterIdx != numClusters - 1) { |
| numBucketsInCluster = targetNumBuckets / numClusters; |
| } else { |
| // If we're in the last cluster, the bucket will contain the remainder of the |
| // frequencies |
| int previousBucketsInCluster = targetNumBuckets / numClusters; |
| numBucketsInCluster = |
| targetNumBuckets - (previousBucketsInCluster * (numClusters - 1)); |
| } |
| |
| final int numFrequenciesInCluster = clusterEndIdx - clusterStartIdx; |
| // If there are less frequencies than buckets in a cluster, we have one bucket per |
| // frequency, and do not use the remaining buckets |
| final int numFrequenciesInBucket = |
| Math.max(1, numFrequenciesInCluster / numBucketsInCluster); |
| for (int bucketIdx = 0; bucketIdx < numBucketsInCluster; bucketIdx++) { |
| int bucketStartIdx = clusterStartIdx + bucketIdx * numFrequenciesInBucket; |
| // If we've gone over the end index, ignore the rest of the buckets for this |
| // cluster |
| if (bucketStartIdx >= clusterEndIdx) { |
| break; |
| } |
| bucketStartIndices.add(bucketStartIdx); |
| } |
| } |
| return ArrayUtils.convertToIntArray(bucketStartIndices); |
| } |
| |
| private static int getLowerBound(int index, int[] startIndices) { |
| return startIndices[index]; |
| } |
| |
| private static int getUpperBound(int index, int[] startIndices, int max) { |
| if (index != startIndices.length - 1) { |
| return startIndices[index + 1]; |
| } else { |
| return max; |
| } |
| } |
| } |
| |
| /** CPU usage of a process */ |
| public static class ProcessCpuUsage { |
| public final int processId; |
| public final String processName; |
| public final int uid; |
| public ArrayList<ThreadCpuUsage> threadCpuUsages; |
| |
| @VisibleForTesting |
| public ProcessCpuUsage( |
| int processId, |
| String processName, |
| int uid, |
| ArrayList<ThreadCpuUsage> threadCpuUsages) { |
| this.processId = processId; |
| this.processName = processName; |
| this.uid = uid; |
| this.threadCpuUsages = threadCpuUsages; |
| } |
| } |
| |
| /** CPU usage of a thread */ |
| public static class ThreadCpuUsage { |
| public final int threadId; |
| public final String threadName; |
| public int[] usageTimesMillis; |
| |
| @VisibleForTesting |
| public ThreadCpuUsage(int threadId, String threadName, int[] usageTimesMillis) { |
| this.threadId = threadId; |
| this.threadName = threadName; |
| this.usageTimesMillis = usageTimesMillis; |
| } |
| } |
| |
| /** Used to inject static methods from {@link Process} */ |
| @VisibleForTesting |
| public static class Injector { |
| /** Get the UID for the process with ID {@code pid} */ |
| public int getUidForPid(int pid) { |
| return Process.getUidForPid(pid); |
| } |
| } |
| } |