1/*
2 * Copyright (C) 2011 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17#define LOG_TAG "ThreadCpuUsage"
18//#define LOG_NDEBUG 0
19
20#include <errno.h>
21#include <stdlib.h>
22#include <string.h>
23#include <time.h>
24
25#include <utils/Log.h>
26
27#include <cpustats/ThreadCpuUsage.h>
28
29namespace android {
30
31bool ThreadCpuUsage::setEnabled(bool isEnabled)
32{
33    bool wasEnabled = mIsEnabled;
34    // only do something if there is a change
35    if (isEnabled != wasEnabled) {
36        ALOGV("setEnabled(%d)", isEnabled);
37        int rc;
38        // enabling
39        if (isEnabled) {
40            rc = clock_gettime(CLOCK_THREAD_CPUTIME_ID, &mPreviousTs);
41            if (rc) {
42                ALOGE("clock_gettime(CLOCK_THREAD_CPUTIME_ID) errno=%d", errno);
43                isEnabled = false;
44            } else {
45                mWasEverEnabled = true;
46                // record wall clock time at first enable
47                if (!mMonotonicKnown) {
48                    rc = clock_gettime(CLOCK_MONOTONIC, &mMonotonicTs);
49                    if (rc) {
50                        ALOGE("clock_gettime(CLOCK_MONOTONIC) errno=%d", errno);
51                    } else {
52                        mMonotonicKnown = true;
53                    }
54                }
55            }
56        // disabling
57        } else {
58            struct timespec ts;
59            rc = clock_gettime(CLOCK_THREAD_CPUTIME_ID, &ts);
60            if (rc) {
61                ALOGE("clock_gettime(CLOCK_THREAD_CPUTIME_ID) errno=%d", errno);
62            } else {
63                long long delta = (ts.tv_sec - mPreviousTs.tv_sec) * 1000000000LL +
64                        (ts.tv_nsec - mPreviousTs.tv_nsec);
65                mAccumulator += delta;
66#if 0
67                mPreviousTs = ts;
68#endif
69            }
70        }
71        mIsEnabled = isEnabled;
72    }
73    return wasEnabled;
74}
75
76bool ThreadCpuUsage::sampleAndEnable(double& ns)
77{
78    bool wasEverEnabled = mWasEverEnabled;
79    if (enable()) {
80        // already enabled, so add a new sample relative to previous
81        return sample(ns);
82    } else if (wasEverEnabled) {
83        // was disabled, but add sample for accumulated time while enabled
84        ns = (double) mAccumulator;
85        mAccumulator = 0;
86        ALOGV("sampleAndEnable %.0f", ns);
87        return true;
88    } else {
89        // first time called
90        ns = 0.0;
91        ALOGV("sampleAndEnable false");
92        return false;
93    }
94}
95
96bool ThreadCpuUsage::sample(double &ns)
97{
98    if (mWasEverEnabled) {
99        if (mIsEnabled) {
100            struct timespec ts;
101            int rc;
102            rc = clock_gettime(CLOCK_THREAD_CPUTIME_ID, &ts);
103            if (rc) {
104                ALOGE("clock_gettime(CLOCK_THREAD_CPUTIME_ID) errno=%d", errno);
105                ns = 0.0;
106                return false;
107            } else {
108                long long delta = (ts.tv_sec - mPreviousTs.tv_sec) * 1000000000LL +
109                        (ts.tv_nsec - mPreviousTs.tv_nsec);
110                mAccumulator += delta;
111                mPreviousTs = ts;
112            }
113        } else {
114            mWasEverEnabled = false;
115        }
116        ns = (double) mAccumulator;
117        ALOGV("sample %.0f", ns);
118        mAccumulator = 0;
119        return true;
120    } else {
121        ALOGW("Can't add sample because measurements have never been enabled");
122        ns = 0.0;
123        return false;
124    }
125}
126
127long long ThreadCpuUsage::elapsed() const
128{
129    long long elapsed;
130    if (mMonotonicKnown) {
131        struct timespec ts;
132        int rc;
133        rc = clock_gettime(CLOCK_MONOTONIC, &ts);
134        if (rc) {
135            ALOGE("clock_gettime(CLOCK_MONOTONIC) errno=%d", errno);
136            elapsed = 0;
137        } else {
138            // mMonotonicTs is updated only at first enable and resetStatistics
139            elapsed = (ts.tv_sec - mMonotonicTs.tv_sec) * 1000000000LL +
140                    (ts.tv_nsec - mMonotonicTs.tv_nsec);
141        }
142    } else {
143        ALOGW("Can't compute elapsed time because measurements have never been enabled");
144        elapsed = 0;
145    }
146    ALOGV("elapsed %lld", elapsed);
147    return elapsed;
148}
149
150void ThreadCpuUsage::resetElapsed()
151{
152    ALOGV("resetElapsed");
153    if (mMonotonicKnown) {
154        int rc;
155        rc = clock_gettime(CLOCK_MONOTONIC, &mMonotonicTs);
156        if (rc) {
157            ALOGE("clock_gettime(CLOCK_MONOTONIC) errno=%d", errno);
158            mMonotonicKnown = false;
159        }
160    }
161}
162
163/*static*/
164int ThreadCpuUsage::sScalingFds[ThreadCpuUsage::MAX_CPU];
165pthread_once_t ThreadCpuUsage::sOnceControl = PTHREAD_ONCE_INIT;
166int ThreadCpuUsage::sKernelMax;
167pthread_mutex_t ThreadCpuUsage::sMutex = PTHREAD_MUTEX_INITIALIZER;
168
169/*static*/
170void ThreadCpuUsage::init()
171{
172    // read the number of CPUs
173    sKernelMax = 1;
174    int fd = open("/sys/devices/system/cpu/kernel_max", O_RDONLY);
175    if (fd >= 0) {
176#define KERNEL_MAX_SIZE 12
177        char kernelMax[KERNEL_MAX_SIZE];
178        ssize_t actual = read(fd, kernelMax, sizeof(kernelMax));
179        if (actual >= 2 && kernelMax[actual-1] == '\n') {
180            sKernelMax = atoi(kernelMax);
181            if (sKernelMax >= MAX_CPU - 1) {
182                ALOGW("kernel_max %d but MAX_CPU %d", sKernelMax, MAX_CPU);
183                sKernelMax = MAX_CPU;
184            } else if (sKernelMax < 0) {
185                ALOGW("kernel_max invalid %d", sKernelMax);
186                sKernelMax = 1;
187            } else {
188                ++sKernelMax;
189                ALOGV("number of CPUs %d", sKernelMax);
190            }
191        } else {
192            ALOGW("Can't read number of CPUs");
193        }
194        (void) close(fd);
195    } else {
196        ALOGW("Can't open number of CPUs");
197    }
198    int i;
199    for (i = 0; i < MAX_CPU; ++i) {
200        sScalingFds[i] = -1;
201    }
202}
203
204uint32_t ThreadCpuUsage::getCpukHz(int cpuNum)
205{
206    if (cpuNum < 0 || cpuNum >= MAX_CPU) {
207        ALOGW("getCpukHz called with invalid CPU %d", cpuNum);
208        return 0;
209    }
210    // double-checked locking idiom is not broken for atomic values such as fd
211    int fd = sScalingFds[cpuNum];
212    if (fd < 0) {
213        // some kernels can't open a scaling file until hot plug complete
214        pthread_mutex_lock(&sMutex);
215        fd = sScalingFds[cpuNum];
216        if (fd < 0) {
217#define FREQ_SIZE 64
218            char freq_path[FREQ_SIZE];
219#define FREQ_DIGIT 27
220            static_assert(MAX_CPU <= 10, "MAX_CPU too large");
221#define FREQ_PATH "/sys/devices/system/cpu/cpu?/cpufreq/scaling_cur_freq"
222            strlcpy(freq_path, FREQ_PATH, sizeof(freq_path));
223            freq_path[FREQ_DIGIT] = cpuNum + '0';
224            fd = open(freq_path, O_RDONLY | O_CLOEXEC);
225            // keep this fd until process exit or exec
226            sScalingFds[cpuNum] = fd;
227        }
228        pthread_mutex_unlock(&sMutex);
229        if (fd < 0) {
230            ALOGW("getCpukHz can't open CPU %d", cpuNum);
231            return 0;
232        }
233    }
234#define KHZ_SIZE 12
235    char kHz[KHZ_SIZE];   // kHz base 10
236    ssize_t actual = pread(fd, kHz, sizeof(kHz), (off_t) 0);
237    uint32_t ret;
238    if (actual >= 2 && kHz[actual-1] == '\n') {
239        ret = atoi(kHz);
240    } else {
241        ret = 0;
242    }
243    if (ret != mCurrentkHz[cpuNum]) {
244        if (ret > 0) {
245            ALOGV("CPU %d frequency %u kHz", cpuNum, ret);
246        } else {
247            ALOGW("Can't read CPU %d frequency", cpuNum);
248        }
249        mCurrentkHz[cpuNum] = ret;
250    }
251    return ret;
252}
253
254}   // namespace android
255