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
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
|
/*
* Copyright (C) 2013 Red Hat, Inc., Frederic Weisbecker <fweisbec@redhat.com>
*
* Licensed under the terms of the GNU GPL License version 2
*
* Selftests for a few posix timers interface.
*
* Kernel loop code stolen from Steven Rostedt <srostedt@redhat.com>
*/
#include <sys/time.h>
#include <stdio.h>
#include <signal.h>
#include <unistd.h>
#include <time.h>
#include <pthread.h>
#define DELAY 2
#define USECS_PER_SEC 1000000
static volatile int done;
/* Busy loop in userspace to elapse ITIMER_VIRTUAL */
static void user_loop(void)
{
while (!done);
}
/*
* Try to spend as much time as possible in kernelspace
* to elapse ITIMER_PROF.
*/
static void kernel_loop(void)
{
void *addr = sbrk(0);
while (!done) {
brk(addr + 4096);
brk(addr);
}
}
/*
* Sleep until ITIMER_REAL expiration.
*/
static void idle_loop(void)
{
pause();
}
static void sig_handler(int nr)
{
done = 1;
}
/*
* Check the expected timer expiration matches the GTOD elapsed delta since
* we armed the timer. Keep a 0.5 sec error margin due to various jitter.
*/
static int check_diff(struct timeval start, struct timeval end)
{
long long diff;
diff = end.tv_usec - start.tv_usec;
diff += (end.tv_sec - start.tv_sec) * USECS_PER_SEC;
if (abs(diff - DELAY * USECS_PER_SEC) > USECS_PER_SEC / 2) {
printf("Diff too high: %lld..", diff);
return -1;
}
return 0;
}
static int check_itimer(int which)
{
int err;
struct timeval start, end;
struct itimerval val = {
.it_value.tv_sec = DELAY,
};
printf("Check itimer ");
if (which == ITIMER_VIRTUAL)
printf("virtual... ");
else if (which == ITIMER_PROF)
printf("prof... ");
else if (which == ITIMER_REAL)
printf("real... ");
fflush(stdout);
done = 0;
if (which == ITIMER_VIRTUAL)
signal(SIGVTALRM, sig_handler);
else if (which == ITIMER_PROF)
signal(SIGPROF, sig_handler);
else if (which == ITIMER_REAL)
signal(SIGALRM, sig_handler);
err = gettimeofday(&start, NULL);
if (err < 0) {
perror("Can't call gettimeofday()\n");
return -1;
}
err = setitimer(which, &val, NULL);
if (err < 0) {
perror("Can't set timer\n");
return -1;
}
if (which == ITIMER_VIRTUAL)
user_loop();
else if (which == ITIMER_PROF)
kernel_loop();
else if (which == ITIMER_REAL)
idle_loop();
gettimeofday(&end, NULL);
if (err < 0) {
perror("Can't call gettimeofday()\n");
return -1;
}
if (!check_diff(start, end))
printf("[OK]\n");
else
printf("[FAIL]\n");
return 0;
}
static int check_timer_create(int which)
{
int err;
timer_t id;
struct timeval start, end;
struct itimerspec val = {
.it_value.tv_sec = DELAY,
};
printf("Check timer_create() ");
if (which == CLOCK_THREAD_CPUTIME_ID) {
printf("per thread... ");
} else if (which == CLOCK_PROCESS_CPUTIME_ID) {
printf("per process... ");
}
fflush(stdout);
done = 0;
err = timer_create(which, NULL, &id);
if (err < 0) {
perror("Can't create timer\n");
return -1;
}
signal(SIGALRM, sig_handler);
err = gettimeofday(&start, NULL);
if (err < 0) {
perror("Can't call gettimeofday()\n");
return -1;
}
err = timer_settime(id, 0, &val, NULL);
if (err < 0) {
perror("Can't set timer\n");
return -1;
}
user_loop();
gettimeofday(&end, NULL);
if (err < 0) {
perror("Can't call gettimeofday()\n");
return -1;
}
if (!check_diff(start, end))
printf("[OK]\n");
else
printf("[FAIL]\n");
return 0;
}
int main(int argc, char **argv)
{
int err;
printf("Testing posix timers. False negative may happen on CPU execution \n");
printf("based timers if other threads run on the CPU...\n");
if (check_itimer(ITIMER_VIRTUAL) < 0)
return -1;
if (check_itimer(ITIMER_PROF) < 0)
return -1;
if (check_itimer(ITIMER_REAL) < 0)
return -1;
if (check_timer_create(CLOCK_THREAD_CPUTIME_ID) < 0)
return -1;
/*
* It's unfortunately hard to reliably test a timer expiration
* on parallel multithread cputime. We could arm it to expire
* on DELAY * nr_threads, with nr_threads busy looping, then wait
* the normal DELAY since the time is elapsing nr_threads faster.
* But for that we need to ensure we have real physical free CPUs
* to ensure true parallelism. So test only one thread until we
* find a better solution.
*/
if (check_timer_create(CLOCK_PROCESS_CPUTIME_ID) < 0)
return -1;
return 0;
}
|
