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 // Minimal test program for clock 18 19 #include <pthread.h> 20 #include <stdio.h> 21 #include <stdlib.h> 22 #include <time.h> 23 #include <unistd.h> 24 25 // this thread soaks the CPU so that clock() function will advance 26 void *cpu_hog(void *arg) 27 { 28 for (;;) { 29 // the system call should not be optimized away by the compiler 30 (void) getpid(); 31 } 32 } 33 34 int main(int argc, char **argv) 35 { 36 pthread_t thread; 37 clock_t ticks10, ticks15; 38 39 // do not call clock() here so we can test initialization 40 41 // soak the CPU for 10 seconds, then read clock 42 pthread_create(&thread, NULL, cpu_hog, NULL); 43 sleep(10); 44 ticks10 = clock(); 45 46 // soak the CPU for 5 more seconds, then read clock 47 sleep(5); 48 ticks15 = clock(); 49 50 // print the results 51 printf("CLOCKS_PER_SEC = %ld ticks/sec\n", (clock_t) CLOCKS_PER_SEC); 52 printf("At 10 secs clock=%lu, at 15 secs clock=%lu\n", ticks10, ticks15); 53 54 // exit could wait for the other thread to complete 55 _exit(EXIT_SUCCESS); 56 } 57
