tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
1// SPDX-License-Identifier: GPL-2.0
2#include <math.h>
3#include <unistd.h>
4#include <stdio.h>
5#include <stdlib.h>
6#include <sys/types.h>
7#include <sys/stat.h>
8#include <fcntl.h>
9#include <sys/timeb.h>
10#include <sched.h>
11#include <errno.h>
12
13void usage(char *name) {
14 printf ("Usage: %s cpunum\n", name);
15}
16
17int main(int argc, char **argv) {
18 unsigned int i, cpu, fd;
19 char msr_file_name[64];
20 long long tsc, old_tsc, new_tsc;
21 long long aperf, old_aperf, new_aperf;
22 long long mperf, old_mperf, new_mperf;
23 struct timeb before, after;
24 long long int start, finish, total;
25 cpu_set_t cpuset;
26
27 if (argc != 2) {
28 usage(argv[0]);
29 return 1;
30 }
31
32 errno = 0;
33 cpu = strtol(argv[1], (char **) NULL, 10);
34
35 if (errno) {
36 usage(argv[0]);
37 return 1;
38 }
39
40 sprintf(msr_file_name, "/dev/cpu/%d/msr", cpu);
41 fd = open(msr_file_name, O_RDONLY);
42
43 if (fd == -1) {
44 perror("Failed to open");
45 return 1;
46 }
47
48 CPU_ZERO(&cpuset);
49 CPU_SET(cpu, &cpuset);
50
51 if (sched_setaffinity(0, sizeof(cpu_set_t), &cpuset)) {
52 perror("Failed to set cpu affinity");
53 return 1;
54 }
55
56 ftime(&before);
57 pread(fd, &old_tsc, sizeof(old_tsc), 0x10);
58 pread(fd, &old_aperf, sizeof(old_mperf), 0xe7);
59 pread(fd, &old_mperf, sizeof(old_aperf), 0xe8);
60
61 for (i=0; i<0x8fffffff; i++) {
62 sqrt(i);
63 }
64
65 ftime(&after);
66 pread(fd, &new_tsc, sizeof(new_tsc), 0x10);
67 pread(fd, &new_aperf, sizeof(new_mperf), 0xe7);
68 pread(fd, &new_mperf, sizeof(new_aperf), 0xe8);
69
70 tsc = new_tsc-old_tsc;
71 aperf = new_aperf-old_aperf;
72 mperf = new_mperf-old_mperf;
73
74 start = before.time*1000 + before.millitm;
75 finish = after.time*1000 + after.millitm;
76 total = finish - start;
77
78 printf("runTime: %4.2f\n", 1.0*total/1000);
79 printf("freq: %7.0f\n", tsc / (1.0*aperf / (1.0 * mperf)) / total);
80 return 0;
81}