| /* |
| * 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 static org.junit.Assert.assertEquals; |
| import static org.junit.Assert.assertNotNull; |
| import static org.junit.Assert.assertTrue; |
| |
| import android.os.SystemClock; |
| import android.support.test.filters.LargeTest; |
| import android.support.test.runner.AndroidJUnit4; |
| |
| import com.android.internal.os.KernelCpuThreadReader.ProcessCpuUsage; |
| import com.android.internal.os.KernelCpuThreadReader.ThreadCpuUsage; |
| |
| import org.junit.Test; |
| import org.junit.runner.RunWith; |
| |
| import java.time.Duration; |
| import java.util.Arrays; |
| import java.util.List; |
| import java.util.OptionalDouble; |
| import java.util.concurrent.CountDownLatch; |
| import java.util.function.Consumer; |
| import java.util.stream.Collectors; |
| |
| /** |
| * End to end test for {@link KernelCpuThreadReader} that checks the accuracy of the reported times |
| * by spawning threads that do a predictable amount of work |
| */ |
| @RunWith(AndroidJUnit4.class) |
| @LargeTest |
| public class KernelCpuThreadReaderEndToEndTest { |
| |
| private static final int TIMED_NUM_SAMPLES = 5; |
| private static final int TIMED_START_MILLIS = 500; |
| private static final int TIMED_END_MILLIS = 2000; |
| private static final int TIMED_INCREMENT_MILLIS = 500; |
| private static final int TIMED_COMPARISON_DELTA_MILLIS = 200; |
| |
| private static final int ITERATIVE_NUM_SAMPLES = 100; |
| private static final long ITERATIVE_LOW_ITERATIONS = (long) 1e8; |
| private static final long ITERATIVE_HIGH_ITERATIONS = (long) 2e8; |
| private static final double ITERATIONS_COMPARISONS_DELTA = 0.25; |
| |
| /** |
| * Test that when we busy-wait for the thread-local time to reach N seconds, the time reported |
| * is also N seconds. Takes ~10s. |
| */ |
| @Test |
| public void testTimedWork() throws InterruptedException { |
| for (int millis = TIMED_START_MILLIS; |
| millis <= TIMED_END_MILLIS; |
| millis += TIMED_INCREMENT_MILLIS) { |
| final Duration targetDuration = Duration.ofMillis(millis); |
| final Runnable work = timedWork(targetDuration); |
| Duration resultDuration = getAverageWorkTime( |
| work, String.format("timed%dms", millis), TIMED_NUM_SAMPLES); |
| assertEquals( |
| "Time worked according to currentThreadTimeMillis doesn't match " |
| + "KernelCpuThreadReader", |
| targetDuration.toMillis(), resultDuration.toMillis(), |
| TIMED_COMPARISON_DELTA_MILLIS); |
| } |
| } |
| |
| /** |
| * Test that when we scale up the amount of work by N, the time reported also scales by N. Takes |
| * ~15s. |
| */ |
| @Test |
| public void testIterativeWork() throws InterruptedException { |
| final Runnable lowAmountWork = iterativeWork(ITERATIVE_LOW_ITERATIONS); |
| final Runnable highAmountWork = iterativeWork(ITERATIVE_HIGH_ITERATIONS); |
| final Duration lowResultDuration = |
| getAverageWorkTime(lowAmountWork, "iterlow", ITERATIVE_NUM_SAMPLES); |
| final Duration highResultDuration = |
| getAverageWorkTime(highAmountWork, "iterhigh", ITERATIVE_NUM_SAMPLES); |
| assertEquals( |
| "Work scale and CPU time scale do not match", |
| ((double) ITERATIVE_HIGH_ITERATIONS) / ((double) ITERATIVE_LOW_ITERATIONS), |
| ((double) highResultDuration.toMillis()) / ((double) lowResultDuration.toMillis()), |
| ITERATIONS_COMPARISONS_DELTA); |
| } |
| |
| /** |
| * Run some work {@code numSamples} times, and take the average CPU duration used for that work |
| * according to {@link KernelCpuThreadReader} |
| */ |
| private Duration getAverageWorkTime( |
| Runnable work, String tag, int numSamples) throws InterruptedException { |
| // Count down every time a thread finishes work, so that we can wait for work to complete |
| final CountDownLatch workFinishedLatch = new CountDownLatch(numSamples); |
| // Count down once when threads can terminate (after we get them from |
| // `KernelCpuThreadReader`) |
| final CountDownLatch threadFinishedLatch = new CountDownLatch(1); |
| |
| // Start `NUM_SAMPLE` threads to do the work |
| for (int i = 0; i < numSamples; i++) { |
| final String threadName = String.format("%s%d", tag, i); |
| // Check the thread name, as we rely on it later to identify threads |
| assertTrue("Max name length for linux threads is 15", threadName.length() <= 15); |
| doWork(work, threadName, workFinishedLatch, threadFinishedLatch); |
| } |
| |
| // Wait for threads to finish |
| workFinishedLatch.await(); |
| |
| // Get thread data from KernelCpuThreadReader |
| final KernelCpuThreadReader kernelCpuThreadReader = KernelCpuThreadReader.create(); |
| assertNotNull(kernelCpuThreadReader); |
| final ProcessCpuUsage currentProcessCpuUsage = |
| kernelCpuThreadReader.getCurrentProcessCpuUsage(); |
| |
| // Threads can terminate, as we've finished crawling them from /proc |
| threadFinishedLatch.countDown(); |
| |
| // Check that we've got times for every thread we spawned |
| final List<ThreadCpuUsage> threadCpuUsages = currentProcessCpuUsage.threadCpuUsages |
| .stream() |
| .filter((thread) -> thread.threadName.startsWith(tag)) |
| .collect(Collectors.toList()); |
| assertEquals( |
| "Incorrect number of threads returned by KernelCpuThreadReader", |
| numSamples, threadCpuUsages.size()); |
| |
| // Calculate the average time spent working |
| final OptionalDouble averageWorkTimeMillis = threadCpuUsages.stream() |
| .mapToDouble((t) -> Arrays.stream(t.usageTimesMillis).sum()) |
| .average(); |
| assertTrue(averageWorkTimeMillis.isPresent()); |
| return Duration.ofMillis((long) averageWorkTimeMillis.getAsDouble()); |
| } |
| |
| /** |
| * Work that lasts {@code duration} according to {@link SystemClock#currentThreadTimeMillis()} |
| */ |
| private Runnable timedWork(Duration duration) { |
| return () -> { |
| // Busy loop until `duration` has elapsed for the thread timer |
| final long startTimeMillis = SystemClock.currentThreadTimeMillis(); |
| final long durationMillis = duration.toMillis(); |
| while (true) { |
| final long elapsedMillis = SystemClock.currentThreadTimeMillis() - startTimeMillis; |
| if (elapsedMillis >= durationMillis) { |
| break; |
| } |
| } |
| }; |
| } |
| |
| /** |
| * Work that iterates {@code iterations} times |
| */ |
| private Runnable iterativeWork(long iterations) { |
| Consumer<Long> empty = (i) -> { |
| }; |
| return () -> { |
| long count = 0; |
| for (long i = 0; i < iterations; i++) { |
| // Alternate branching to reduce effect of branch prediction |
| if (i % 2 == 0) { |
| count++; |
| } |
| } |
| // Call empty function with value to avoid loop getting optimized away |
| empty.accept(count); |
| }; |
| } |
| |
| /** |
| * Perform some work in another thread |
| * |
| * @param work the work to perform |
| * @param threadName the name of the spawned thread |
| * @param workFinishedLatch latch to register that the work has been completed |
| * @param threadFinishedLatch latch to pause termination of the thread until the latch is |
| * decremented |
| */ |
| private void doWork( |
| Runnable work, |
| String threadName, |
| CountDownLatch workFinishedLatch, |
| CountDownLatch threadFinishedLatch) { |
| Runnable workWrapped = () -> { |
| // Do the work |
| work.run(); |
| // Notify that the work is finished |
| workFinishedLatch.countDown(); |
| // Wait until `threadFinishLatch` has been released in order to keep the thread alive so |
| // we can see it in `proc` filesystem |
| try { |
| threadFinishedLatch.await(); |
| } catch (InterruptedException e) { |
| e.printStackTrace(); |
| } |
| }; |
| new Thread(workWrapped, threadName).start(); |
| } |
| } |