1 #include <math.h>
2 #include <unistd.h>
3 #include <stdio.h>
4 #include <stdlib.h>
5 #include <sys/types.h>
6 #include <sys/stat.h>
7 #include <fcntl.h>
8 #include <sys/timeb.h>
9 #include <sched.h>
10 #include <errno.h>
11 
12 void usage(char *name) {
13 	printf ("Usage: %s cpunum\n", name);
14 }
15 
16 int main(int argc, char **argv) {
17 	int i, cpu, fd;
18 	char msr_file_name[64];
19 	long long tsc, old_tsc, new_tsc;
20 	long long aperf, old_aperf, new_aperf;
21 	long long mperf, old_mperf, new_mperf;
22 	struct timeb before, after;
23 	long long int start, finish, total;
24 	cpu_set_t cpuset;
25 
26 	if (argc != 2) {
27 		usage(argv[0]);
28 		return 1;
29 	}
30 
31 	errno = 0;
32 	cpu = strtol(argv[1], (char **) NULL, 10);
33 
34 	if (errno) {
35 		usage(argv[0]);
36 		return 1;
37 	}
38 
39 	sprintf(msr_file_name, "/dev/cpu/%d/msr", cpu);
40 	fd = open(msr_file_name, O_RDONLY);
41 
42 	if (fd == -1) {
43 		perror("Failed to open");
44 		return 1;
45 	}
46 
47 	CPU_ZERO(&cpuset);
48 	CPU_SET(cpu, &cpuset);
49 
50 	if (sched_setaffinity(0, sizeof(cpu_set_t), &cpuset)) {
51 		perror("Failed to set cpu affinity");
52 		return 1;
53 	}
54 
55 	ftime(&before);
56 	pread(fd, &old_tsc,  sizeof(old_tsc), 0x10);
57 	pread(fd, &old_aperf,  sizeof(old_mperf), 0xe7);
58 	pread(fd, &old_mperf,  sizeof(old_aperf), 0xe8);
59 
60 	for (i=0; i<0x8fffffff; i++) {
61 		sqrt(i);
62 	}
63 
64 	ftime(&after);
65 	pread(fd, &new_tsc,  sizeof(new_tsc), 0x10);
66 	pread(fd, &new_aperf,  sizeof(new_mperf), 0xe7);
67 	pread(fd, &new_mperf,  sizeof(new_aperf), 0xe8);
68 
69 	tsc = new_tsc-old_tsc;
70 	aperf = new_aperf-old_aperf;
71 	mperf = new_mperf-old_mperf;
72 
73 	start = before.time*1000 + before.millitm;
74 	finish = after.time*1000 + after.millitm;
75 	total = finish - start;
76 
77 	printf("runTime: %4.2f\n", 1.0*total/1000);
78 	printf("freq: %7.0f\n", tsc / (1.0*aperf / (1.0 * mperf)) / total);
79 	return 0;
80 }
81