-
Notifications
You must be signed in to change notification settings - Fork 1
/
ctxSwBench.c
105 lines (88 loc) · 2.58 KB
/
ctxSwBench.c
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
#include <stdio.h>
#include <stdlib.h>
#include <sched.h>
#include <time.h>
#include <errno.h>
#include <getopt.h>
#include <unistd.h> /* usleep */
#include <sys/syscall.h>
static void myPerror(const char *msg, int rc)
{
perror(msg);
exit(rc);
}
static long myAtoi(const char *str)
{
char *end;
long ret;
if ('\0' == str[0]) {
fprintf(stderr, "myAtoi: empty string");
exit(30);
}
errno = 0;
ret = strtol(str, &end, 0);
if (errno)
myPerror("strtol", 31);
if ('\0' != *end) {
fprintf(stderr, "myAtoi: erroneous input \"%s\"", str);
exit(32);
}
return ret;
}
#define FUNC_UNDER_TEST() getpid()
enum EnumMode {
EnumModeSched,
EnumModePid
};
int main(int argc, char *argv[])
{
size_t i, nRep = 1000, nPrevRep = 0, sleepDurUsec = 0;
double elapsedUsec;
struct timespec ts0, ts1;
enum EnumMode mode = EnumModeSched;
char optchr;
while (-1 != (optchr = getopt(argc, argv, "n:N:s:PSh"))) {
switch (optchr) {
case 'n': nRep = myAtoi(optarg); break;
case 'N': nPrevRep = myAtoi(optarg); break;
case 's': sleepDurUsec = myAtoi(optarg); break;
case 'P': mode = EnumModePid; break;
case 'S': mode = EnumModeSched; break;
default:
exit(10);
}
}
switch (mode) {
case EnumModeSched:
{
for (i = 0; i < nPrevRep; ++i) {
clock_gettime(CLOCK_MONOTONIC, &ts0);
syscall(SYS_sched_yield);
}
if (0 < sleepDurUsec)
usleep(sleepDurUsec);
clock_gettime(CLOCK_MONOTONIC, &ts0);
for (i = 0; i < nRep; ++i)
syscall(SYS_sched_yield);
clock_gettime(CLOCK_MONOTONIC, &ts1);
}
break;
case EnumModePid:
{
for (i = 0; i < nPrevRep; ++i) {
clock_gettime(CLOCK_MONOTONIC, &ts0);
syscall(SYS_getpid);
}
if (0 < sleepDurUsec)
usleep(sleepDurUsec);
clock_gettime(CLOCK_MONOTONIC, &ts0);
for (i = 0; i < nRep; ++i)
syscall(SYS_getpid);
clock_gettime(CLOCK_MONOTONIC, &ts1);
}
break;
}
elapsedUsec = 1e6 * (ts1.tv_sec - ts0.tv_sec) + 1e-3 * (ts1.tv_nsec - ts0.tv_nsec);
printf("Elapsed time is %f usec (%f nsec per call.)\n", elapsedUsec, 1e3 * elapsedUsec / nRep);
return 0;
}