diff --git a/services/surfaceflinger/FrameTracker.cpp b/services/surfaceflinger/FrameTracker.cpp
new file mode 100644
index 0000000..5c66ff9
--- /dev/null
+++ b/services/surfaceflinger/FrameTracker.cpp
@@ -0,0 +1,132 @@
+/*
+ * 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.
+ */
+
+// This is needed for stdint.h to define INT64_MAX in C++
+#define __STDC_LIMIT_MACROS
+
+#include <ui/Fence.h>
+
+#include <utils/String8.h>
+
+#include "FrameTracker.h"
+
+namespace android {
+
+FrameTracker::FrameTracker() :
+        mOffset(0),
+        mNumFences(0) {
+}
+
+void FrameTracker::setDesiredPresentTime(nsecs_t presentTime) {
+    mFrameRecords[mOffset].desiredPresentTime = presentTime;
+}
+
+void FrameTracker::setFrameReadyTime(nsecs_t readyTime) {
+    mFrameRecords[mOffset].frameReadyTime = readyTime;
+}
+
+void FrameTracker::setFrameReadyFence(const sp<Fence>& readyFence) {
+    mFrameRecords[mOffset].frameReadyFence = readyFence;
+    mNumFences++;
+}
+
+void FrameTracker::setActualPresentTime(nsecs_t presentTime) {
+    mFrameRecords[mOffset].actualPresentTime = presentTime;
+}
+
+void FrameTracker::setActualPresentFence(const sp<Fence>& readyFence) {
+    mFrameRecords[mOffset].actualPresentFence = readyFence;
+    mNumFences++;
+}
+
+void FrameTracker::advanceFrame() {
+    mOffset = (mOffset+1) % NUM_FRAME_RECORDS;
+    mFrameRecords[mOffset].desiredPresentTime = INT64_MAX;
+    mFrameRecords[mOffset].frameReadyTime = INT64_MAX;
+    mFrameRecords[mOffset].actualPresentTime = INT64_MAX;
+
+    if (mFrameRecords[mOffset].frameReadyFence != NULL) {
+        // We're clobbering an unsignaled fence, so we need to decrement the
+        // fence count.
+        mFrameRecords[mOffset].frameReadyFence = NULL;
+        mNumFences--;
+    }
+
+    if (mFrameRecords[mOffset].actualPresentFence != NULL) {
+        // We're clobbering an unsignaled fence, so we need to decrement the
+        // fence count.
+        mFrameRecords[mOffset].actualPresentFence = NULL;
+        mNumFences--;
+    }
+
+    // Clean up the signaled fences to keep the number of open fence FDs in
+    // this process reasonable.
+    processFences();
+}
+
+void FrameTracker::clear() {
+    for (size_t i = 0; i < NUM_FRAME_RECORDS; i++) {
+        mFrameRecords[i].desiredPresentTime = 0;
+        mFrameRecords[i].frameReadyTime = 0;
+        mFrameRecords[i].actualPresentTime = 0;
+        mFrameRecords[i].frameReadyFence.clear();
+        mFrameRecords[i].actualPresentFence.clear();
+    }
+    mNumFences = 0;
+}
+
+void FrameTracker::processFences() const {
+    FrameRecord* records = const_cast<FrameRecord*>(mFrameRecords);
+    int& numFences = const_cast<int&>(mNumFences);
+
+    for (int i = 1; i < NUM_FRAME_RECORDS && numFences > 0; i++) {
+        size_t idx = (mOffset+NUM_FRAME_RECORDS-i) % NUM_FRAME_RECORDS;
+
+        const sp<Fence>& rfence = records[idx].frameReadyFence;
+        if (rfence != NULL) {
+            records[idx].frameReadyTime = rfence->getSignalTime();
+            if (records[idx].frameReadyTime < INT64_MAX) {
+                records[idx].frameReadyFence = NULL;
+                numFences--;
+            }
+        }
+
+        const sp<Fence>& pfence = records[idx].actualPresentFence;
+        if (pfence != NULL) {
+            records[idx].actualPresentTime = pfence->getSignalTime();
+            if (records[idx].actualPresentTime < INT64_MAX) {
+                records[idx].actualPresentFence = NULL;
+                numFences--;
+            }
+        }
+    }
+}
+
+void FrameTracker::dump(String8& result) const {
+    processFences();
+
+    const size_t o = mOffset;
+    for (size_t i = 1; i < NUM_FRAME_RECORDS; i++) {
+        const size_t index = (o+i) % NUM_FRAME_RECORDS;
+        result.appendFormat("%lld\t%lld\t%lld\n",
+            mFrameRecords[index].desiredPresentTime,
+            mFrameRecords[index].actualPresentTime,
+            mFrameRecords[index].frameReadyTime);
+    }
+    result.append("\n");
+}
+
+} // namespace android