Fix parsing of kernel wakelocks
We handled stale wakelocks (wakelocks that disappear from /d/wakeup_sources)
differently in previous version of Android. They would be set stale, but still be
updated with their previous counts (they would never disappear).
The method setStale has been replaced with endSample(), which is semantically different.
Once a SamplingTimer has endSample() called, it expects any future calls to update() to
be a new sample, meaning the entire amount passed to update() is included in the kernel
wakelock's total. Since stale wakelocks were never removed from the list, this would
increase by large amounts when nothing had actually changed.
This was exacerbated by the fact that there was a bug where the last wakelock in
/d/wakeup_sources was never parsed, so if the order ever changed, this "stale" wakelock
would suddenly re-appear and the entire amount reported would be charged to the wakelock,
instead of just the difference since the last update.
All this was exposed when we added support to handle wakelocks that would disappear and
reappear with smaller values, meaning the kernel had pruned them from its accounting and
reset them.
Bug:28601080
Change-Id: Ic96027f7d580dac5e20aa73d67e5cedac4ccabeb
diff --git a/core/java/com/android/internal/os/BatteryStatsImpl.java b/core/java/com/android/internal/os/BatteryStatsImpl.java
index 937fc75..93dc625 100644
--- a/core/java/com/android/internal/os/BatteryStatsImpl.java
+++ b/core/java/com/android/internal/os/BatteryStatsImpl.java
@@ -8873,8 +8873,6 @@
return;
}
- // Record whether we've seen a non-zero time (for debugging b/22716723).
- boolean seenNonZeroTime = false;
for (Map.Entry<String, KernelWakelockStats.Entry> ent : wakelockStats.entrySet()) {
String name = ent.getKey();
KernelWakelockStats.Entry kws = ent.getValue();
@@ -8884,27 +8882,24 @@
kwlt = new SamplingTimer(mClocks, mOnBatteryScreenOffTimeBase);
mKernelWakelockStats.put(name, kwlt);
}
+
kwlt.update(kws.mTotalTime, kws.mCount);
kwlt.setUpdateVersion(kws.mVersion);
-
- if (kws.mVersion != wakelockStats.kernelWakelockVersion) {
- seenNonZeroTime |= kws.mTotalTime > 0;
- }
}
int numWakelocksSetStale = 0;
- if (wakelockStats.size() != mKernelWakelockStats.size()) {
- // Set timers to stale if they didn't appear in /proc/wakelocks this time.
- for (Map.Entry<String, SamplingTimer> ent : mKernelWakelockStats.entrySet()) {
- SamplingTimer st = ent.getValue();
- if (st.getUpdateVersion() != wakelockStats.kernelWakelockVersion) {
- st.endSample();
- numWakelocksSetStale++;
- }
+ // Set timers to stale if they didn't appear in /d/wakeup_sources (or /proc/wakelocks)
+ // this time.
+ for (Map.Entry<String, SamplingTimer> ent : mKernelWakelockStats.entrySet()) {
+ SamplingTimer st = ent.getValue();
+ if (st.getUpdateVersion() != wakelockStats.kernelWakelockVersion) {
+ st.endSample();
+ numWakelocksSetStale++;
}
}
- if (!seenNonZeroTime) {
+ // Record whether we've seen a non-zero time (for debugging b/22716723).
+ if (wakelockStats.isEmpty()) {
Slog.wtf(TAG, "All kernel wakelocks had time of zero");
}
diff --git a/core/java/com/android/internal/os/KernelWakelockReader.java b/core/java/com/android/internal/os/KernelWakelockReader.java
index 6654ea5..8036f257 100644
--- a/core/java/com/android/internal/os/KernelWakelockReader.java
+++ b/core/java/com/android/internal/os/KernelWakelockReader.java
@@ -18,6 +18,8 @@
import android.os.Process;
import android.util.Slog;
+import com.android.internal.annotations.VisibleForTesting;
+
import java.io.FileInputStream;
import java.util.Iterator;
@@ -106,14 +108,14 @@
/**
* Reads the wakelocks and updates the staleStats with the new information.
*/
- private KernelWakelockStats parseProcWakelocks(byte[] wlBuffer, int len, boolean wakeup_sources,
- final KernelWakelockStats staleStats) {
+ @VisibleForTesting
+ public KernelWakelockStats parseProcWakelocks(byte[] wlBuffer, int len, boolean wakeup_sources,
+ final KernelWakelockStats staleStats) {
String name;
int count;
long totalTime;
int startIndex;
int endIndex;
- int numUpdatedWlNames = 0;
// Advance past the first line.
int i;
@@ -126,11 +128,10 @@
for (endIndex=startIndex;
endIndex < len && wlBuffer[endIndex] != '\n' && wlBuffer[endIndex] != '\0';
endIndex++);
- endIndex++; // endIndex is an exclusive upper bound.
// Don't go over the end of the buffer, Process.parseProcLine might
// write to wlBuffer[endIndex]
- if (endIndex >= (len - 1) ) {
- return staleStats;
+ if (endIndex > (len - 1) ) {
+ break;
}
String[] nameStringArray = mProcWakelocksName;
@@ -161,7 +162,6 @@
if (!staleStats.containsKey(name)) {
staleStats.put(name, new KernelWakelockStats.Entry(count, totalTime,
sKernelWakelockUpdateVersion));
- numUpdatedWlNames++;
} else {
KernelWakelockStats.Entry kwlStats = staleStats.get(name);
if (kwlStats.mVersion == sKernelWakelockUpdateVersion) {
@@ -171,7 +171,6 @@
kwlStats.mCount = count;
kwlStats.mTotalTime = totalTime;
kwlStats.mVersion = sKernelWakelockUpdateVersion;
- numUpdatedWlNames++;
}
}
} else if (!parsed) {
@@ -182,16 +181,14 @@
Slog.wtf(TAG, "Failed to parse proc line!");
}
}
- startIndex = endIndex;
+ startIndex = endIndex + 1;
}
- if (staleStats.size() != numUpdatedWlNames) {
- // Don't report old data.
- Iterator<KernelWakelockStats.Entry> itr = staleStats.values().iterator();
- while (itr.hasNext()) {
- if (itr.next().mVersion != sKernelWakelockUpdateVersion) {
- itr.remove();
- }
+ // Don't report old data.
+ Iterator<KernelWakelockStats.Entry> itr = staleStats.values().iterator();
+ while (itr.hasNext()) {
+ if (itr.next().mVersion != sKernelWakelockUpdateVersion) {
+ itr.remove();
}
}
diff --git a/core/tests/coretests/src/com/android/internal/os/KernelWakelockReaderTest.java b/core/tests/coretests/src/com/android/internal/os/KernelWakelockReaderTest.java
new file mode 100644
index 0000000..4e4bb3507
--- /dev/null
+++ b/core/tests/coretests/src/com/android/internal/os/KernelWakelockReaderTest.java
@@ -0,0 +1,147 @@
+/*
+ * Copyright (C) 2016 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.support.test.filters.SmallTest;
+
+import junit.framework.TestCase;
+
+import java.nio.charset.Charset;
+
+public class KernelWakelockReaderTest extends TestCase {
+ /**
+ * Helper class that builds the mock Kernel module file /d/wakeup_sources.
+ */
+ private static class ProcFileBuilder {
+ private final static String sHeader = "name\t\tactive_count\tevent_count\twakeup_count\t" +
+ "expire_count\tactive_since\ttotal_time\tmax_time\tlast_change\t" +
+ "prevent_suspend_time\n";
+
+ private StringBuilder mStringBuilder;
+
+ private void ensureHeader() {
+ if (mStringBuilder == null) {
+ mStringBuilder = new StringBuilder();
+ mStringBuilder.append(sHeader);
+ }
+ }
+
+ public ProcFileBuilder addLine(String name, int count, long timeMillis) {
+ ensureHeader();
+ mStringBuilder.append(name).append("\t").append(count).append("\t0\t0\t0\t0\t")
+ .append(timeMillis).append("\t0\t0\t0\n");
+ return this;
+ }
+
+ public byte[] getBytes() throws Exception {
+ ensureHeader();
+ byte[] data = mStringBuilder.toString().getBytes(Charset.forName("UTF-8"));
+
+ // The Kernel puts a \0 at the end of the data. Since each of our lines ends with \n,
+ // we override the last \n with a \0.
+ data[data.length - 1] = 0;
+ return data;
+ }
+ }
+
+ private KernelWakelockReader mReader;
+
+ @Override
+ public void setUp() throws Exception {
+ super.setUp();
+ mReader = new KernelWakelockReader();
+ }
+
+ @SmallTest
+ public void testParseEmptyFile() throws Exception {
+ KernelWakelockStats staleStats = mReader.parseProcWakelocks(new byte[0], 0, true,
+ new KernelWakelockStats());
+ assertTrue(staleStats.isEmpty());
+ }
+
+ @SmallTest
+ public void testOnlyHeader() throws Exception {
+ byte[] buffer = new ProcFileBuilder().getBytes();
+ KernelWakelockStats staleStats = mReader.parseProcWakelocks(buffer, buffer.length, true,
+ new KernelWakelockStats());
+ assertTrue(staleStats.isEmpty());
+ }
+
+ @SmallTest
+ public void testOneWakelock() throws Exception {
+ byte[] buffer = new ProcFileBuilder()
+ .addLine("Wakelock", 34, 123) // Milliseconds
+ .getBytes();
+ KernelWakelockStats staleStats = mReader.parseProcWakelocks(buffer, buffer.length, true,
+ new KernelWakelockStats());
+ assertEquals(1, staleStats.size());
+ assertTrue(staleStats.containsKey("Wakelock"));
+
+ KernelWakelockStats.Entry entry = staleStats.get("Wakelock");
+ assertEquals(34, entry.mCount);
+ assertEquals(123 * 1000, entry.mTotalTime); // Microseconds
+ }
+
+ @SmallTest
+ public void testTwoWakelocks() throws Exception {
+ byte[] buffer = new ProcFileBuilder()
+ .addLine("Wakelock", 1, 10)
+ .addLine("Fakelock", 2, 20)
+ .getBytes();
+ KernelWakelockStats staleStats = mReader.parseProcWakelocks(buffer, buffer.length, true,
+ new KernelWakelockStats());
+ assertEquals(2, staleStats.size());
+ assertTrue(staleStats.containsKey("Wakelock"));
+ assertTrue(staleStats.containsKey("Fakelock"));
+ }
+
+ @SmallTest
+ public void testDuplicateWakelocksAccumulate() throws Exception {
+ byte[] buffer = new ProcFileBuilder()
+ .addLine("Wakelock", 1, 10) // Milliseconds
+ .addLine("Wakelock", 1, 10) // Milliseconds
+ .getBytes();
+ KernelWakelockStats staleStats = mReader.parseProcWakelocks(buffer, buffer.length, true,
+ new KernelWakelockStats());
+ assertEquals(1, staleStats.size());
+ assertTrue(staleStats.containsKey("Wakelock"));
+
+ KernelWakelockStats.Entry entry = staleStats.get("Wakelock");
+ assertEquals(2, entry.mCount);
+ assertEquals(20 * 1000, entry.mTotalTime); // Microseconds
+ }
+
+ @SmallTest
+ public void testWakelocksBecomeStale() throws Exception {
+ byte[] buffer = new ProcFileBuilder()
+ .addLine("Fakelock", 3, 30)
+ .getBytes();
+ KernelWakelockStats staleStats = new KernelWakelockStats();
+
+ staleStats = mReader.parseProcWakelocks(buffer, buffer.length, true, staleStats);
+ assertEquals(1, staleStats.size());
+ assertTrue(staleStats.containsKey("Fakelock"));
+
+ buffer = new ProcFileBuilder()
+ .addLine("Wakelock", 1, 10)
+ .getBytes();
+
+ staleStats = mReader.parseProcWakelocks(buffer, buffer.length, true, staleStats);
+ assertEquals(1, staleStats.size());
+ assertTrue(staleStats.containsKey("Wakelock"));
+ assertFalse(staleStats.containsKey("Fakelock"));
+ }
+}
