http://www.kernel.org/doc/man-pages/online/pages/man3/pthread_getcpuclockid.3.html
EXAMPLE top
The program below creates a thread and then uses clock_gettime(3) to retrieve
the total process CPU time, and the per-thread CPU time consumed by the two
threads. The following shell session shows an example run:
$ ./a.out
Main thread sleeping
Sub-thread starting infinite loop
Main thread consuming some CPU time...
Process total CPU time: 1.368
Main thread CPU time: 0.376
Sub-thread CPU time: 0.992
Program source
/* Link with "-lrt" */
#include <time.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <pthread.h>
#include <string.h>
#include <errno.h>
#define handle_error(msg) \
do { perror(msg); exit(EXIT_FAILURE); } while (0)
#define handle_error_en(en, msg) \
do { errno = en; perror(msg); exit(EXIT_FAILURE); } while (0)
static void *
thread_start(void *arg)
{
printf("Sub-thread starting infinite loop\n");
for (;;)
continue;
}
static void
pclock(char *msg, clockid_t cid)
{
struct timespec ts;
printf("%s", msg);
if (clock_gettime(cid, &ts) == -1)
handle_error("clock_gettime");
printf("%4ld.%03ld\n", ts.tv_sec, ts.tv_nsec / 1000000);
}
int
main(int argc, char *argv[])
{
pthread_t thread;
clockid_t cid;
int j, s;
s = pthread_create(&thread, NULL, thread_start, NULL);
if (s != 0)
handle_error_en(s, "pthread_create");
printf("Main thread sleeping\n");
sleep(1);
printf("Main thread consuming some CPU time...\n");
for (j = 0; j < 2000000; j++)
getppid();
pclock("Process total CPU time: ", CLOCK_PROCESS_CPUTIME_ID);
s = pthread_getcpuclockid(pthread_self(), &cid);
if (s != 0)
handle_error_en(s, "pthread_getcpuclockid");
pclock("Main thread CPU time: ", cid);
/* The preceding 4 lines of code could have been replaced by:
pclock("Main thread CPU time: ", CLOCK_THREAD_CPUTIME_ID); */
s = pthread_getcpuclockid(thread, &cid);
if (s != 0)
handle_error_en(s, "pthread_getcpuclockid");
pclock("Sub-thread CPU time: ", cid);
exit(EXIT_SUCCESS); /* Terminates both threads */
}
