diff --git a/libs/cpustats/Android.mk b/libs/cpustats/Android.mk
new file mode 100644
index 0000000..b506353
--- /dev/null
+++ b/libs/cpustats/Android.mk
@@ -0,0 +1,11 @@
+LOCAL_PATH:= $(call my-dir)
+
+include $(CLEAR_VARS)
+
+LOCAL_SRC_FILES :=     \
+        CentralTendencyStatistics.cpp \
+        ThreadCpuUsage.cpp
+
+LOCAL_MODULE := libcpustats
+
+include $(BUILD_STATIC_LIBRARY)
diff --git a/libs/cpustats/CentralTendencyStatistics.cpp b/libs/cpustats/CentralTendencyStatistics.cpp
new file mode 100644
index 0000000..42ab62b
--- /dev/null
+++ b/libs/cpustats/CentralTendencyStatistics.cpp
@@ -0,0 +1,81 @@
+/*
+ * Copyright (C) 2011 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.
+ */
+
+#include <stdlib.h>
+
+#include <cpustats/CentralTendencyStatistics.h>
+
+void CentralTendencyStatistics::sample(double x)
+{
+    // update min and max
+    if (x < mMinimum)
+        mMinimum = x;
+    if (x > mMaximum)
+        mMaximum = x;
+    // Knuth
+    if (mN == 0) {
+        mMean = 0;
+    }
+    ++mN;
+    double delta = x - mMean;
+    mMean += delta / mN;
+    mM2 += delta * (x - mMean);
+}
+
+void CentralTendencyStatistics::reset()
+{
+    mMean = NAN;
+    mMedian = NAN;
+    mMinimum = INFINITY;
+    mMaximum = -INFINITY;
+    mN = 0;
+    mM2 = 0;
+    mVariance = NAN;
+    mVarianceKnownForN = 0;
+    mStddev = NAN;
+    mStddevKnownForN = 0;
+}
+
+double CentralTendencyStatistics::variance() const
+{
+    double variance;
+    if (mVarianceKnownForN != mN) {
+        if (mN > 1) {
+            // double variance_n = M2/n;
+            variance = mM2 / (mN - 1);
+        } else {
+            variance = NAN;
+        }
+        mVariance = variance;
+        mVarianceKnownForN = mN;
+    } else {
+        variance = mVariance;
+    }
+    return variance;
+}
+
+double CentralTendencyStatistics::stddev() const
+{
+    double stddev;
+    if (mStddevKnownForN != mN) {
+        stddev = sqrt(variance());
+        mStddev = stddev;
+        mStddevKnownForN = mN;
+    } else {
+        stddev = mStddev;
+    }
+    return stddev;
+}
diff --git a/libs/cpustats/ThreadCpuUsage.cpp b/libs/cpustats/ThreadCpuUsage.cpp
new file mode 100644
index 0000000..99b4c83
--- /dev/null
+++ b/libs/cpustats/ThreadCpuUsage.cpp
@@ -0,0 +1,252 @@
+/*
+ * Copyright (C) 2011 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 "ThreadCpuUsage"
+//#define LOG_NDEBUG 0
+
+#include <errno.h>
+#include <stdlib.h>
+#include <time.h>
+
+#include <utils/Debug.h>
+#include <utils/Log.h>
+
+#include <cpustats/ThreadCpuUsage.h>
+
+namespace android {
+
+bool ThreadCpuUsage::setEnabled(bool isEnabled)
+{
+    bool wasEnabled = mIsEnabled;
+    // only do something if there is a change
+    if (isEnabled != wasEnabled) {
+        ALOGV("setEnabled(%d)", isEnabled);
+        int rc;
+        // enabling
+        if (isEnabled) {
+            rc = clock_gettime(CLOCK_THREAD_CPUTIME_ID, &mPreviousTs);
+            if (rc) {
+                ALOGE("clock_gettime(CLOCK_THREAD_CPUTIME_ID) errno=%d", errno);
+                isEnabled = false;
+            } else {
+                mWasEverEnabled = true;
+                // record wall clock time at first enable
+                if (!mMonotonicKnown) {
+                    rc = clock_gettime(CLOCK_MONOTONIC, &mMonotonicTs);
+                    if (rc) {
+                        ALOGE("clock_gettime(CLOCK_MONOTONIC) errno=%d", errno);
+                    } else {
+                        mMonotonicKnown = true;
+                    }
+                }
+            }
+        // disabling
+        } else {
+            struct timespec ts;
+            rc = clock_gettime(CLOCK_THREAD_CPUTIME_ID, &ts);
+            if (rc) {
+                ALOGE("clock_gettime(CLOCK_THREAD_CPUTIME_ID) errno=%d", errno);
+            } else {
+                long long delta = (ts.tv_sec - mPreviousTs.tv_sec) * 1000000000LL +
+                        (ts.tv_nsec - mPreviousTs.tv_nsec);
+                mAccumulator += delta;
+#if 0
+                mPreviousTs = ts;
+#endif
+            }
+        }
+        mIsEnabled = isEnabled;
+    }
+    return wasEnabled;
+}
+
+bool ThreadCpuUsage::sampleAndEnable(double& ns)
+{
+    bool ret;
+    bool wasEverEnabled = mWasEverEnabled;
+    if (enable()) {
+        // already enabled, so add a new sample relative to previous
+        return sample(ns);
+    } else if (wasEverEnabled) {
+        // was disabled, but add sample for accumulated time while enabled
+        ns = (double) mAccumulator;
+        mAccumulator = 0;
+        ALOGV("sampleAndEnable %.0f", ns);
+        return true;
+    } else {
+        // first time called
+        ns = 0.0;
+        ALOGV("sampleAndEnable false");
+        return false;
+    }
+}
+
+bool ThreadCpuUsage::sample(double &ns)
+{
+    if (mWasEverEnabled) {
+        if (mIsEnabled) {
+            struct timespec ts;
+            int rc;
+            rc = clock_gettime(CLOCK_THREAD_CPUTIME_ID, &ts);
+            if (rc) {
+                ALOGE("clock_gettime(CLOCK_THREAD_CPUTIME_ID) errno=%d", errno);
+                ns = 0.0;
+                return false;
+            } else {
+                long long delta = (ts.tv_sec - mPreviousTs.tv_sec) * 1000000000LL +
+                        (ts.tv_nsec - mPreviousTs.tv_nsec);
+                mAccumulator += delta;
+                mPreviousTs = ts;
+            }
+        } else {
+            mWasEverEnabled = false;
+        }
+        ns = (double) mAccumulator;
+        ALOGV("sample %.0f", ns);
+        mAccumulator = 0;
+        return true;
+    } else {
+        ALOGW("Can't add sample because measurements have never been enabled");
+        ns = 0.0;
+        return false;
+    }
+}
+
+long long ThreadCpuUsage::elapsed() const
+{
+    long long elapsed;
+    if (mMonotonicKnown) {
+        struct timespec ts;
+        int rc;
+        rc = clock_gettime(CLOCK_MONOTONIC, &ts);
+        if (rc) {
+            ALOGE("clock_gettime(CLOCK_MONOTONIC) errno=%d", errno);
+            elapsed = 0;
+        } else {
+            // mMonotonicTs is updated only at first enable and resetStatistics
+            elapsed = (ts.tv_sec - mMonotonicTs.tv_sec) * 1000000000LL +
+                    (ts.tv_nsec - mMonotonicTs.tv_nsec);
+        }
+    } else {
+        ALOGW("Can't compute elapsed time because measurements have never been enabled");
+        elapsed = 0;
+    }
+    ALOGV("elapsed %lld", elapsed);
+    return elapsed;
+}
+
+void ThreadCpuUsage::resetElapsed()
+{
+    ALOGV("resetElapsed");
+    if (mMonotonicKnown) {
+        int rc;
+        rc = clock_gettime(CLOCK_MONOTONIC, &mMonotonicTs);
+        if (rc) {
+            ALOGE("clock_gettime(CLOCK_MONOTONIC) errno=%d", errno);
+            mMonotonicKnown = false;
+        }
+    }
+}
+
+/*static*/
+int ThreadCpuUsage::sScalingFds[ThreadCpuUsage::MAX_CPU];
+pthread_once_t ThreadCpuUsage::sOnceControl = PTHREAD_ONCE_INIT;
+int ThreadCpuUsage::sKernelMax;
+
+/*static*/
+void ThreadCpuUsage::init()
+{
+    // read the number of CPUs
+    sKernelMax = 1;
+    int fd = open("/sys/devices/system/cpu/kernel_max", O_RDONLY);
+    if (fd >= 0) {
+#define KERNEL_MAX_SIZE 12
+        char kernelMax[KERNEL_MAX_SIZE];
+        ssize_t actual = read(fd, kernelMax, sizeof(kernelMax));
+        if (actual >= 2 && kernelMax[actual-1] == '\n') {
+            sKernelMax = atoi(kernelMax);
+            if (sKernelMax >= MAX_CPU - 1) {
+                ALOGW("kernel_max %d but MAX_CPU %d", sKernelMax, MAX_CPU);
+                sKernelMax = MAX_CPU;
+            } else if (sKernelMax < 0) {
+                ALOGW("kernel_max invalid %d", sKernelMax);
+                sKernelMax = 1;
+            } else {
+                ++sKernelMax;
+                ALOGV("number of CPUs %d", sKernelMax);
+            }
+        } else {
+            ALOGW("Can't read number of CPUs");
+        }
+        (void) close(fd);
+    } else {
+        ALOGW("Can't open number of CPUs");
+    }
+
+    // open fd to each frequency per CPU
+#define FREQ_SIZE 64
+    char freq_path[FREQ_SIZE];
+#define FREQ_DIGIT 27
+    COMPILE_TIME_ASSERT_FUNCTION_SCOPE(MAX_CPU <= 10);
+    strlcpy(freq_path, "/sys/devices/system/cpu/cpu?/cpufreq/scaling_cur_freq", sizeof(freq_path));
+    int i;
+    for (i = 0; i < MAX_CPU; ++i) {
+        sScalingFds[i] = -1;
+    }
+    for (i = 0; i < sKernelMax; ++i) {
+        freq_path[FREQ_DIGIT] = i + '0';
+        fd = open(freq_path, O_RDONLY);
+        if (fd >= 0) {
+            // keep this fd until process exit
+            sScalingFds[i] = fd;
+        } else {
+            ALOGW("Can't open CPU %d", i);
+        }
+    }
+}
+
+uint32_t ThreadCpuUsage::getCpukHz(int cpuNum)
+{
+    if (cpuNum < 0 || cpuNum >= MAX_CPU) {
+        ALOGW("getCpukHz called with invalid CPU %d", cpuNum);
+        return 0;
+    }
+    int fd = sScalingFds[cpuNum];
+    if (fd < 0) {
+        ALOGW("getCpukHz called for unopened CPU %d", cpuNum);
+        return 0;
+    }
+#define KHZ_SIZE 12
+    char kHz[KHZ_SIZE];   // kHz base 10
+    ssize_t actual = pread(fd, kHz, sizeof(kHz), (off_t) 0);
+    uint32_t ret;
+    if (actual >= 2 && kHz[actual-1] == '\n') {
+        ret = atoi(kHz);
+    } else {
+        ret = 0;
+    }
+    if (ret != mCurrentkHz[cpuNum]) {
+        if (ret > 0) {
+            ALOGV("CPU %d frequency %u kHz", cpuNum, ret);
+        } else {
+            ALOGW("Can't read CPU %d frequency", cpuNum);
+        }
+        mCurrentkHz[cpuNum] = ret;
+    }
+    return ret;
+}
+
+}   // namespace android