This source file includes following definitions.
- altivec_touch_fn
- touch
- start_thread_on
- start_process_on
- sigalrm_handler
- sigusr1_handler
- pipe_setup
- pipe_thread1
- pipe_thread2
- yield_setup
- yield_thread1
- yield_thread2
- sys_futex
- cmpxchg
- xchg
- mutex_lock
- mutex_unlock
- futex_setup
- futex_thread1
- futex_thread2
- usage
- main
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8 #define _GNU_SOURCE
9 #include <errno.h>
10 #include <sched.h>
11 #include <string.h>
12 #include <stdio.h>
13 #include <unistd.h>
14 #include <stdlib.h>
15 #include <getopt.h>
16 #include <signal.h>
17 #include <assert.h>
18 #include <pthread.h>
19 #include <limits.h>
20 #include <sys/time.h>
21 #include <sys/syscall.h>
22 #include <sys/types.h>
23 #include <sys/shm.h>
24 #include <linux/futex.h>
25 #ifdef __powerpc__
26 #include <altivec.h>
27 #endif
28 #include "utils.h"
29
30 static unsigned int timeout = 30;
31
32 static int touch_vdso;
33 struct timeval tv;
34
35 static int touch_fp = 1;
36 double fp;
37
38 static int touch_vector = 1;
39 vector int a, b, c;
40
41 #ifdef __powerpc__
42 static int touch_altivec = 1;
43
44
45
46
47
48 static void __attribute__((__target__("no-vsx"))) altivec_touch_fn(void)
49 {
50 c = a + b;
51 }
52 #endif
53
54 static void touch(void)
55 {
56 if (touch_vdso)
57 gettimeofday(&tv, NULL);
58
59 if (touch_fp)
60 fp += 0.1;
61
62 #ifdef __powerpc__
63 if (touch_altivec)
64 altivec_touch_fn();
65 #endif
66
67 if (touch_vector)
68 c = a + b;
69
70 asm volatile("# %0 %1 %2": : "r"(&tv), "r"(&fp), "r"(&c));
71 }
72
73 static void start_thread_on(void *(*fn)(void *), void *arg, unsigned long cpu)
74 {
75 int rc;
76 pthread_t tid;
77 cpu_set_t cpuset;
78 pthread_attr_t attr;
79
80 CPU_ZERO(&cpuset);
81 CPU_SET(cpu, &cpuset);
82
83 rc = pthread_attr_init(&attr);
84 if (rc) {
85 errno = rc;
86 perror("pthread_attr_init");
87 exit(1);
88 }
89
90 rc = pthread_attr_setaffinity_np(&attr, sizeof(cpu_set_t), &cpuset);
91 if (rc) {
92 errno = rc;
93 perror("pthread_attr_setaffinity_np");
94 exit(1);
95 }
96
97 rc = pthread_create(&tid, &attr, fn, arg);
98 if (rc) {
99 errno = rc;
100 perror("pthread_create");
101 exit(1);
102 }
103 }
104
105 static void start_process_on(void *(*fn)(void *), void *arg, unsigned long cpu)
106 {
107 int pid;
108 cpu_set_t cpuset;
109
110 pid = fork();
111 if (pid == -1) {
112 perror("fork");
113 exit(1);
114 }
115
116 if (pid)
117 return;
118
119 CPU_ZERO(&cpuset);
120 CPU_SET(cpu, &cpuset);
121
122 if (sched_setaffinity(0, sizeof(cpuset), &cpuset)) {
123 perror("sched_setaffinity");
124 exit(1);
125 }
126
127 fn(arg);
128
129 exit(0);
130 }
131
132 static unsigned long iterations;
133 static unsigned long iterations_prev;
134
135 static void sigalrm_handler(int junk)
136 {
137 unsigned long i = iterations;
138
139 printf("%ld\n", i - iterations_prev);
140 iterations_prev = i;
141
142 if (--timeout == 0)
143 kill(0, SIGUSR1);
144
145 alarm(1);
146 }
147
148 static void sigusr1_handler(int junk)
149 {
150 exit(0);
151 }
152
153 struct actions {
154 void (*setup)(int, int);
155 void *(*thread1)(void *);
156 void *(*thread2)(void *);
157 };
158
159 #define READ 0
160 #define WRITE 1
161
162 static int pipe_fd1[2];
163 static int pipe_fd2[2];
164
165 static void pipe_setup(int cpu1, int cpu2)
166 {
167 if (pipe(pipe_fd1) || pipe(pipe_fd2))
168 exit(1);
169 }
170
171 static void *pipe_thread1(void *arg)
172 {
173 signal(SIGALRM, sigalrm_handler);
174 alarm(1);
175
176 while (1) {
177 assert(read(pipe_fd1[READ], &c, 1) == 1);
178 touch();
179
180 assert(write(pipe_fd2[WRITE], &c, 1) == 1);
181 touch();
182
183 iterations += 2;
184 }
185
186 return NULL;
187 }
188
189 static void *pipe_thread2(void *arg)
190 {
191 while (1) {
192 assert(write(pipe_fd1[WRITE], &c, 1) == 1);
193 touch();
194
195 assert(read(pipe_fd2[READ], &c, 1) == 1);
196 touch();
197 }
198
199 return NULL;
200 }
201
202 static struct actions pipe_actions = {
203 .setup = pipe_setup,
204 .thread1 = pipe_thread1,
205 .thread2 = pipe_thread2,
206 };
207
208 static void yield_setup(int cpu1, int cpu2)
209 {
210 if (cpu1 != cpu2) {
211 fprintf(stderr, "Both threads must be on the same CPU for yield test\n");
212 exit(1);
213 }
214 }
215
216 static void *yield_thread1(void *arg)
217 {
218 signal(SIGALRM, sigalrm_handler);
219 alarm(1);
220
221 while (1) {
222 sched_yield();
223 touch();
224
225 iterations += 2;
226 }
227
228 return NULL;
229 }
230
231 static void *yield_thread2(void *arg)
232 {
233 while (1) {
234 sched_yield();
235 touch();
236 }
237
238 return NULL;
239 }
240
241 static struct actions yield_actions = {
242 .setup = yield_setup,
243 .thread1 = yield_thread1,
244 .thread2 = yield_thread2,
245 };
246
247 static long sys_futex(void *addr1, int op, int val1, struct timespec *timeout,
248 void *addr2, int val3)
249 {
250 return syscall(SYS_futex, addr1, op, val1, timeout, addr2, val3);
251 }
252
253 static unsigned long cmpxchg(unsigned long *p, unsigned long expected,
254 unsigned long desired)
255 {
256 unsigned long exp = expected;
257
258 __atomic_compare_exchange_n(p, &exp, desired, 0,
259 __ATOMIC_SEQ_CST, __ATOMIC_SEQ_CST);
260 return exp;
261 }
262
263 static unsigned long xchg(unsigned long *p, unsigned long val)
264 {
265 return __atomic_exchange_n(p, val, __ATOMIC_SEQ_CST);
266 }
267
268 static int processes;
269
270 static int mutex_lock(unsigned long *m)
271 {
272 int c;
273 int flags = FUTEX_WAIT;
274 if (!processes)
275 flags |= FUTEX_PRIVATE_FLAG;
276
277 c = cmpxchg(m, 0, 1);
278 if (!c)
279 return 0;
280
281 if (c == 1)
282 c = xchg(m, 2);
283
284 while (c) {
285 sys_futex(m, flags, 2, NULL, NULL, 0);
286 c = xchg(m, 2);
287 }
288
289 return 0;
290 }
291
292 static int mutex_unlock(unsigned long *m)
293 {
294 int flags = FUTEX_WAKE;
295 if (!processes)
296 flags |= FUTEX_PRIVATE_FLAG;
297
298 if (*m == 2)
299 *m = 0;
300 else if (xchg(m, 0) == 1)
301 return 0;
302
303 sys_futex(m, flags, 1, NULL, NULL, 0);
304
305 return 0;
306 }
307
308 static unsigned long *m1, *m2;
309
310 static void futex_setup(int cpu1, int cpu2)
311 {
312 if (!processes) {
313 static unsigned long _m1, _m2;
314 m1 = &_m1;
315 m2 = &_m2;
316 } else {
317 int shmid;
318 void *shmaddr;
319
320 shmid = shmget(IPC_PRIVATE, getpagesize(), SHM_R | SHM_W);
321 if (shmid < 0) {
322 perror("shmget");
323 exit(1);
324 }
325
326 shmaddr = shmat(shmid, NULL, 0);
327 if (shmaddr == (char *)-1) {
328 perror("shmat");
329 shmctl(shmid, IPC_RMID, NULL);
330 exit(1);
331 }
332
333 shmctl(shmid, IPC_RMID, NULL);
334
335 m1 = shmaddr;
336 m2 = shmaddr + sizeof(*m1);
337 }
338
339 *m1 = 0;
340 *m2 = 0;
341
342 mutex_lock(m1);
343 mutex_lock(m2);
344 }
345
346 static void *futex_thread1(void *arg)
347 {
348 signal(SIGALRM, sigalrm_handler);
349 alarm(1);
350
351 while (1) {
352 mutex_lock(m2);
353 mutex_unlock(m1);
354
355 iterations += 2;
356 }
357
358 return NULL;
359 }
360
361 static void *futex_thread2(void *arg)
362 {
363 while (1) {
364 mutex_unlock(m2);
365 mutex_lock(m1);
366 }
367
368 return NULL;
369 }
370
371 static struct actions futex_actions = {
372 .setup = futex_setup,
373 .thread1 = futex_thread1,
374 .thread2 = futex_thread2,
375 };
376
377 static struct option options[] = {
378 { "test", required_argument, 0, 't' },
379 { "process", no_argument, &processes, 1 },
380 { "timeout", required_argument, 0, 's' },
381 { "vdso", no_argument, &touch_vdso, 1 },
382 { "no-fp", no_argument, &touch_fp, 0 },
383 #ifdef __powerpc__
384 { "no-altivec", no_argument, &touch_altivec, 0 },
385 #endif
386 { "no-vector", no_argument, &touch_vector, 0 },
387 { 0, },
388 };
389
390 static void usage(void)
391 {
392 fprintf(stderr, "Usage: context_switch2 <options> CPU1 CPU2\n\n");
393 fprintf(stderr, "\t\t--test=X\tpipe, futex or yield (default)\n");
394 fprintf(stderr, "\t\t--process\tUse processes (default threads)\n");
395 fprintf(stderr, "\t\t--timeout=X\tDuration in seconds to run (default 30)\n");
396 fprintf(stderr, "\t\t--vdso\t\ttouch VDSO\n");
397 fprintf(stderr, "\t\t--no-fp\t\tDon't touch FP\n");
398 #ifdef __powerpc__
399 fprintf(stderr, "\t\t--no-altivec\tDon't touch altivec\n");
400 #endif
401 fprintf(stderr, "\t\t--no-vector\tDon't touch vector\n");
402 }
403
404 int main(int argc, char *argv[])
405 {
406 signed char c;
407 struct actions *actions = &yield_actions;
408 int cpu1;
409 int cpu2;
410 static void (*start_fn)(void *(*fn)(void *), void *arg, unsigned long cpu);
411
412 while (1) {
413 int option_index = 0;
414
415 c = getopt_long(argc, argv, "", options, &option_index);
416
417 if (c == -1)
418 break;
419
420 switch (c) {
421 case 0:
422 if (options[option_index].flag != 0)
423 break;
424
425 usage();
426 exit(1);
427 break;
428
429 case 't':
430 if (!strcmp(optarg, "pipe")) {
431 actions = &pipe_actions;
432 } else if (!strcmp(optarg, "yield")) {
433 actions = &yield_actions;
434 } else if (!strcmp(optarg, "futex")) {
435 actions = &futex_actions;
436 } else {
437 usage();
438 exit(1);
439 }
440 break;
441
442 case 's':
443 timeout = atoi(optarg);
444 break;
445
446 default:
447 usage();
448 exit(1);
449 }
450 }
451
452 if (processes)
453 start_fn = start_process_on;
454 else
455 start_fn = start_thread_on;
456
457 if (((argc - optind) != 2)) {
458 cpu1 = cpu2 = pick_online_cpu();
459 } else {
460 cpu1 = atoi(argv[optind++]);
461 cpu2 = atoi(argv[optind++]);
462 }
463
464 printf("Using %s with ", processes ? "processes" : "threads");
465
466 if (actions == &pipe_actions)
467 printf("pipe");
468 else if (actions == &yield_actions)
469 printf("yield");
470 else
471 printf("futex");
472
473 printf(" on cpus %d/%d touching FP:%s altivec:%s vector:%s vdso:%s\n",
474 cpu1, cpu2, touch_fp ? "yes" : "no", touch_altivec ? "yes" : "no",
475 touch_vector ? "yes" : "no", touch_vdso ? "yes" : "no");
476
477
478 setpgid(getpid(), getpid());
479
480 signal(SIGUSR1, sigusr1_handler);
481
482 actions->setup(cpu1, cpu2);
483
484 start_fn(actions->thread1, NULL, cpu1);
485 start_fn(actions->thread2, NULL, cpu2);
486
487 while (1)
488 sleep(3600);
489
490 return 0;
491 }