diff --git a/services/audioflinger/Android.mk b/services/audioflinger/Android.mk
index ee843aa..f32d90f 100644
--- a/services/audioflinger/Android.mk
+++ b/services/audioflinger/Android.mk
@@ -95,4 +95,8 @@
 # 47.5 seconds at 44.1 kHz, 8 megabytes
 # LOCAL_CFLAGS += -DTEE_SINK_FRAMES=0x200000
 
+# uncomment to enable the audio watchdog
+LOCAL_SRC_FILES += AudioWatchdog.cpp
+LOCAL_CFLAGS += -DAUDIO_WATCHDOG
+
 include $(BUILD_SHARED_LIBRARY)
diff --git a/services/audioflinger/AudioFlinger.cpp b/services/audioflinger/AudioFlinger.cpp
index be59ca0..586a916 100644
--- a/services/audioflinger/AudioFlinger.cpp
+++ b/services/audioflinger/AudioFlinger.cpp
@@ -2300,6 +2300,19 @@
         }
 #endif
 
+#ifdef AUDIO_WATCHDOG
+        // create and start the watchdog
+        mAudioWatchdog = new AudioWatchdog();
+        mAudioWatchdog->setDump(&mAudioWatchdogDump);
+        mAudioWatchdog->run("AudioWatchdog", PRIORITY_URGENT_AUDIO);
+        tid = mAudioWatchdog->getTid();
+        err = requestPriority(getpid_cached, tid, 1);
+        if (err != 0) {
+            ALOGW("Policy SCHED_FIFO priority %d is unavailable for pid %d tid %d; error %d",
+                    1, getpid_cached, tid, err);
+        }
+#endif
+
     } else {
         mFastMixer = NULL;
     }
@@ -2349,6 +2362,11 @@
         }
         delete mSoaker;
 #endif
+        if (mAudioWatchdog != 0) {
+            mAudioWatchdog->requestExit();
+            mAudioWatchdog->requestExitAndWait();
+            mAudioWatchdog.clear();
+        }
     }
     delete mAudioMixer;
 }
@@ -2670,6 +2688,9 @@
                 if (old == -1) {
                     __futex_syscall3(&mFastMixerFutex, FUTEX_WAKE_PRIVATE, 1);
                 }
+                if (mAudioWatchdog != 0) {
+                    mAudioWatchdog->resume();
+                }
             }
             state->mCommand = FastMixerState::MIX_WRITE;
             sq->end();
@@ -2746,6 +2767,9 @@
             if (kUseFastMixer == FastMixer_Dynamic) {
                 mNormalSink = mOutputSink;
             }
+            if (mAudioWatchdog != 0) {
+                mAudioWatchdog->pause();
+            }
         } else {
             sq->end(false /*didModify*/);
         }
@@ -3234,6 +3258,7 @@
     }
 
     // Push the new FastMixer state if necessary
+    bool pauseAudioWatchdog = false;
     if (didModify) {
         state->mFastTracksGen++;
         // if the fast mixer was active, but now there are no fast tracks, then put it in cold idle
@@ -3249,6 +3274,7 @@
             // If we go into cold idle, need to wait for acknowledgement
             // so that fast mixer stops doing I/O.
             block = FastMixerStateQueue::BLOCK_UNTIL_ACKED;
+            pauseAudioWatchdog = true;
         }
         sq->end();
     }
@@ -3256,6 +3282,9 @@
         sq->end(didModify);
         sq->push(block);
     }
+    if (pauseAudioWatchdog && mAudioWatchdog != 0) {
+        mAudioWatchdog->pause();
+    }
 
     // Now perform the deferred reset on fast tracks that have stopped
     while (resetMask != 0) {
@@ -3576,6 +3605,12 @@
         }
     }
 
+    if (mAudioWatchdog != 0) {
+        // Make a non-atomic copy of audio watchdog dump so it won't change underneath us
+        AudioWatchdogDump wdCopy = mAudioWatchdogDump;
+        wdCopy.dump(fd);
+    }
+
     return NO_ERROR;
 }
 
diff --git a/services/audioflinger/AudioFlinger.h b/services/audioflinger/AudioFlinger.h
index 677d466..384306c 100644
--- a/services/audioflinger/AudioFlinger.h
+++ b/services/audioflinger/AudioFlinger.h
@@ -49,6 +49,7 @@
 #include "ExtendedAudioBufferProvider.h"
 #include "FastMixer.h"
 #include "NBAIO.h"
+#include "AudioWatchdog.h"
 
 #include <powermanager/IPowerManager.h>
 
@@ -1169,6 +1170,7 @@
 #endif
                     // one-time initialization, no locks required
                     FastMixer*  mFastMixer;         // non-NULL if there is also a fast mixer
+                    sp<AudioWatchdog> mAudioWatchdog; // non-0 if there is an audio watchdog thread
 
                     // contents are not guaranteed to be consistent, no locks required
                     FastMixerDumpState mFastMixerDumpState;
@@ -1176,6 +1178,7 @@
                     StateQueueObserverDump mStateQueueObserverDump;
                     StateQueueMutatorDump  mStateQueueMutatorDump;
 #endif
+                    AudioWatchdogDump mAudioWatchdogDump;
 
                     // accessible only within the threadLoop(), no locks required
                     //          mFastMixer->sq()    // for mutating and pushing state
diff --git a/services/audioflinger/AudioWatchdog.cpp b/services/audioflinger/AudioWatchdog.cpp
new file mode 100644
index 0000000..8f328ee
--- /dev/null
+++ b/services/audioflinger/AudioWatchdog.cpp
@@ -0,0 +1,134 @@
+/*
+ * Copyright (C) 2012 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.
+ */
+
+#define LOG_TAG "AudioWatchdog"
+//#define LOG_NDEBUG 0
+
+#include <utils/Log.h>
+#include "AudioWatchdog.h"
+
+namespace android {
+
+void AudioWatchdogDump::dump(int fd)
+{
+    char buf[32];
+    if (mMostRecent != 0) {
+        // includes NUL terminator
+        ctime_r(&mMostRecent, buf);
+    } else {
+        strcpy(buf, "N/A\n");
+    }
+    fdprintf(fd, "Watchdog: underruns=%u, logs=%u, most recent underrun log at %s",
+            mUnderruns, mLogs, buf);
+}
+
+bool AudioWatchdog::threadLoop()
+{
+    {
+        AutoMutex _l(mMyLock);
+        if (mPaused) {
+            mMyCond.wait(mMyLock);
+            // ignore previous timestamp after resume()
+            mOldTsValid = false;
+            // force an immediate log on first underrun after resume()
+            mLogTs.tv_sec = MIN_TIME_BETWEEN_LOGS_SEC;
+            mLogTs.tv_nsec = 0;
+            // caller will check for exitPending()
+            return true;
+        }
+    }
+    struct timespec newTs;
+    int rc = clock_gettime(CLOCK_MONOTONIC, &newTs);
+    if (rc != 0) {
+        pause();
+        return false;
+    }
+    if (!mOldTsValid) {
+        mOldTs = newTs;
+        mOldTsValid = true;
+        return true;
+    }
+    time_t sec = newTs.tv_sec - mOldTs.tv_sec;
+    long nsec = newTs.tv_nsec - mOldTs.tv_nsec;
+    if (nsec < 0) {
+        --sec;
+        nsec += 1000000000;
+    }
+    mOldTs = newTs;
+    // cycleNs is same as sec*1e9 + nsec, but limited to about 4 seconds
+    uint32_t cycleNs = nsec;
+    if (sec > 0) {
+        if (sec < 4) {
+            cycleNs += sec * 1000000000;
+        } else {
+            cycleNs = 4000000000u;
+        }
+    }
+    mLogTs.tv_sec += sec;
+    if ((mLogTs.tv_nsec += nsec) >= 1000000000) {
+        mLogTs.tv_sec++;
+        mLogTs.tv_nsec -= 1000000000;
+    }
+    if (cycleNs > mMaxCycleNs) {
+        mDump->mUnderruns = ++mUnderruns;
+        if (mLogTs.tv_sec >= MIN_TIME_BETWEEN_LOGS_SEC) {
+            mDump->mLogs = ++mLogs;
+            mDump->mMostRecent = time(NULL);
+            ALOGW("Insufficient CPU for load: expected=%.1f actual=%.1f ms; underruns=%u logs=%u",
+                mPeriodNs * 1e-6, cycleNs * 1e-6, mUnderruns, mLogs);
+            mLogTs.tv_sec = 0;
+            mLogTs.tv_nsec = 0;
+        }
+    }
+    struct timespec req;
+    req.tv_sec = 0;
+    req.tv_nsec = mPeriodNs;
+    rc = nanosleep(&req, NULL);
+    if (!((rc == 0) || (rc == -1 && errno == EINTR))) {
+        pause();
+        return false;
+    }
+    return true;
+}
+
+void AudioWatchdog::requestExit()
+{
+    // must be in this order to avoid a race condition
+    Thread::requestExit();
+    resume();
+}
+
+void AudioWatchdog::pause()
+{
+    AutoMutex _l(mMyLock);
+    mPaused = true;
+}
+
+void AudioWatchdog::resume()
+{
+    AutoMutex _l(mMyLock);
+    if (mPaused) {
+        mPaused = false;
+        mMyCond.signal();
+    }
+}
+
+void AudioWatchdog::setDump(AudioWatchdogDump *dump)
+{
+    mDump = dump != NULL ? dump : &mDummyDump;
+}
+
+}   // namespace android
diff --git a/services/audioflinger/AudioWatchdog.h b/services/audioflinger/AudioWatchdog.h
new file mode 100644
index 0000000..4657530
--- /dev/null
+++ b/services/audioflinger/AudioWatchdog.h
@@ -0,0 +1,88 @@
+/*
+ * Copyright (C) 2012 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.
+ */
+
+// The watchdog thread runs periodically.  It has two functions:
+//   (a) verify that adequate CPU time is available, and log
+//       as soon as possible when there appears to be a CPU shortage
+//   (b) monitor the other threads [not yet implemented]
+
+#ifndef AUDIO_WATCHDOG_H
+#define AUDIO_WATCHDOG_H
+
+#include <time.h>
+#include <utils/Thread.h>
+
+namespace android {
+
+// Keeps a cache of AudioWatchdog statistics that can be logged by dumpsys.
+// The usual caveats about atomicity of information apply.
+struct AudioWatchdogDump {
+    AudioWatchdogDump() : mUnderruns(0), mLogs(0), mMostRecent(0) { }
+    /*virtual*/ ~AudioWatchdogDump() { }
+    uint32_t mUnderruns;    // total number of underruns
+    uint32_t mLogs;         // total number of log messages
+    time_t   mMostRecent;   // time of most recent log
+    void     dump(int fd);  // should only be called on a stable copy, not the original
+};
+
+class AudioWatchdog : public Thread {
+
+public:
+    AudioWatchdog(unsigned periodMs = 50) : Thread(false /*canCallJava*/), mPaused(false),
+            mPeriodNs(periodMs * 1000000), mMaxCycleNs(mPeriodNs * 2),
+            // mOldTs
+            // mLogTs initialized below
+            mOldTsValid(false), mUnderruns(0), mLogs(0), mDump(&mDummyDump)
+        {
+#define MIN_TIME_BETWEEN_LOGS_SEC 60
+            // force an immediate log on first underrun
+            mLogTs.tv_sec = MIN_TIME_BETWEEN_LOGS_SEC;
+            mLogTs.tv_nsec = 0;
+        }
+    virtual         ~AudioWatchdog() { }
+
+     // Do not call Thread::requestExitAndWait() without first calling requestExit().
+    // Thread::requestExitAndWait() is not virtual, and the implementation doesn't do enough.
+    virtual void        requestExit();
+
+    // FIXME merge API and implementation with AudioTrackThread
+    void            pause();        // suspend thread from execution at next loop boundary
+    void            resume();       // allow thread to execute, if not requested to exit
+
+    // Where to store the dump, or NULL to not update
+    void            setDump(AudioWatchdogDump* dump);
+
+private:
+    virtual bool    threadLoop();
+
+    Mutex           mMyLock;        // Thread::mLock is private
+    Condition       mMyCond;        // Thread::mThreadExitedCondition is private
+    bool            mPaused;        // whether thread is currently paused
+
+    uint32_t        mPeriodNs;      // nominal period
+    uint32_t        mMaxCycleNs;    // maximum allowed time of one cycle before declaring underrun
+    struct timespec mOldTs;         // monotonic time when threadLoop last ran
+    struct timespec mLogTs;         // time since last log
+    bool            mOldTsValid;    // whether mOldTs is valid
+    uint32_t        mUnderruns;     // total number of underruns
+    uint32_t        mLogs;          // total number of logs
+    AudioWatchdogDump*  mDump;      // where to store the dump, always non-NULL
+    AudioWatchdogDump   mDummyDump; // default area for dump in case setDump() is not called
+};
+
+}   // namespace android
+
+#endif  // AUDIO_WATCHDOG_H