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12#define _GNU_SOURCE
13#include <errno.h>
14#include <sched.h>
15#include <string.h>
16#include <stdio.h>
17#include <unistd.h>
18#include <stdlib.h>
19#include <getopt.h>
20#include <signal.h>
21#include <assert.h>
22#include <pthread.h>
23#include <limits.h>
24#include <sys/time.h>
25#include <sys/syscall.h>
26#include <sys/types.h>
27#include <sys/shm.h>
28#include <linux/futex.h>
29#ifdef __powerpc__
30#include <altivec.h>
31#endif
32#include "utils.h"
33
34static unsigned int timeout = 30;
35
36static int touch_vdso;
37struct timeval tv;
38
39static int touch_fp = 1;
40double fp;
41
42static int touch_vector = 1;
43vector int a, b, c;
44
45#ifdef __powerpc__
46static int touch_altivec = 1;
47
48
49
50
51
52static void __attribute__((__target__("no-vsx"))) altivec_touch_fn(void)
53{
54 c = a + b;
55}
56#endif
57
58static void touch(void)
59{
60 if (touch_vdso)
61 gettimeofday(&tv, NULL);
62
63 if (touch_fp)
64 fp += 0.1;
65
66#ifdef __powerpc__
67 if (touch_altivec)
68 altivec_touch_fn();
69#endif
70
71 if (touch_vector)
72 c = a + b;
73
74 asm volatile("# %0 %1 %2": : "r"(&tv), "r"(&fp), "r"(&c));
75}
76
77static void start_thread_on(void *(*fn)(void *), void *arg, unsigned long cpu)
78{
79 int rc;
80 pthread_t tid;
81 cpu_set_t cpuset;
82 pthread_attr_t attr;
83
84 CPU_ZERO(&cpuset);
85 CPU_SET(cpu, &cpuset);
86
87 rc = pthread_attr_init(&attr);
88 if (rc) {
89 errno = rc;
90 perror("pthread_attr_init");
91 exit(1);
92 }
93
94 rc = pthread_attr_setaffinity_np(&attr, sizeof(cpu_set_t), &cpuset);
95 if (rc) {
96 errno = rc;
97 perror("pthread_attr_setaffinity_np");
98 exit(1);
99 }
100
101 rc = pthread_create(&tid, &attr, fn, arg);
102 if (rc) {
103 errno = rc;
104 perror("pthread_create");
105 exit(1);
106 }
107}
108
109static void start_process_on(void *(*fn)(void *), void *arg, unsigned long cpu)
110{
111 int pid;
112 cpu_set_t cpuset;
113
114 pid = fork();
115 if (pid == -1) {
116 perror("fork");
117 exit(1);
118 }
119
120 if (pid)
121 return;
122
123 CPU_ZERO(&cpuset);
124 CPU_SET(cpu, &cpuset);
125
126 if (sched_setaffinity(0, sizeof(cpuset), &cpuset)) {
127 perror("sched_setaffinity");
128 exit(1);
129 }
130
131 fn(arg);
132
133 exit(0);
134}
135
136static unsigned long iterations;
137static unsigned long iterations_prev;
138
139static void sigalrm_handler(int junk)
140{
141 unsigned long i = iterations;
142
143 printf("%ld\n", i - iterations_prev);
144 iterations_prev = i;
145
146 if (--timeout == 0)
147 kill(0, SIGUSR1);
148
149 alarm(1);
150}
151
152static void sigusr1_handler(int junk)
153{
154 exit(0);
155}
156
157struct actions {
158 void (*setup)(int, int);
159 void *(*thread1)(void *);
160 void *(*thread2)(void *);
161};
162
163#define READ 0
164#define WRITE 1
165
166static int pipe_fd1[2];
167static int pipe_fd2[2];
168
169static void pipe_setup(int cpu1, int cpu2)
170{
171 if (pipe(pipe_fd1) || pipe(pipe_fd2))
172 exit(1);
173}
174
175static void *pipe_thread1(void *arg)
176{
177 signal(SIGALRM, sigalrm_handler);
178 alarm(1);
179
180 while (1) {
181 assert(read(pipe_fd1[READ], &c, 1) == 1);
182 touch();
183
184 assert(write(pipe_fd2[WRITE], &c, 1) == 1);
185 touch();
186
187 iterations += 2;
188 }
189
190 return NULL;
191}
192
193static void *pipe_thread2(void *arg)
194{
195 while (1) {
196 assert(write(pipe_fd1[WRITE], &c, 1) == 1);
197 touch();
198
199 assert(read(pipe_fd2[READ], &c, 1) == 1);
200 touch();
201 }
202
203 return NULL;
204}
205
206static struct actions pipe_actions = {
207 .setup = pipe_setup,
208 .thread1 = pipe_thread1,
209 .thread2 = pipe_thread2,
210};
211
212static void yield_setup(int cpu1, int cpu2)
213{
214 if (cpu1 != cpu2) {
215 fprintf(stderr, "Both threads must be on the same CPU for yield test\n");
216 exit(1);
217 }
218}
219
220static void *yield_thread1(void *arg)
221{
222 signal(SIGALRM, sigalrm_handler);
223 alarm(1);
224
225 while (1) {
226 sched_yield();
227 touch();
228
229 iterations += 2;
230 }
231
232 return NULL;
233}
234
235static void *yield_thread2(void *arg)
236{
237 while (1) {
238 sched_yield();
239 touch();
240 }
241
242 return NULL;
243}
244
245static struct actions yield_actions = {
246 .setup = yield_setup,
247 .thread1 = yield_thread1,
248 .thread2 = yield_thread2,
249};
250
251static long sys_futex(void *addr1, int op, int val1, struct timespec *timeout,
252 void *addr2, int val3)
253{
254 return syscall(SYS_futex, addr1, op, val1, timeout, addr2, val3);
255}
256
257static unsigned long cmpxchg(unsigned long *p, unsigned long expected,
258 unsigned long desired)
259{
260 unsigned long exp = expected;
261
262 __atomic_compare_exchange_n(p, &exp, desired, 0,
263 __ATOMIC_SEQ_CST, __ATOMIC_SEQ_CST);
264 return exp;
265}
266
267static unsigned long xchg(unsigned long *p, unsigned long val)
268{
269 return __atomic_exchange_n(p, val, __ATOMIC_SEQ_CST);
270}
271
272static int processes;
273
274static int mutex_lock(unsigned long *m)
275{
276 int c;
277 int flags = FUTEX_WAIT;
278 if (!processes)
279 flags |= FUTEX_PRIVATE_FLAG;
280
281 c = cmpxchg(m, 0, 1);
282 if (!c)
283 return 0;
284
285 if (c == 1)
286 c = xchg(m, 2);
287
288 while (c) {
289 sys_futex(m, flags, 2, NULL, NULL, 0);
290 c = xchg(m, 2);
291 }
292
293 return 0;
294}
295
296static int mutex_unlock(unsigned long *m)
297{
298 int flags = FUTEX_WAKE;
299 if (!processes)
300 flags |= FUTEX_PRIVATE_FLAG;
301
302 if (*m == 2)
303 *m = 0;
304 else if (xchg(m, 0) == 1)
305 return 0;
306
307 sys_futex(m, flags, 1, NULL, NULL, 0);
308
309 return 0;
310}
311
312static unsigned long *m1, *m2;
313
314static void futex_setup(int cpu1, int cpu2)
315{
316 if (!processes) {
317 static unsigned long _m1, _m2;
318 m1 = &_m1;
319 m2 = &_m2;
320 } else {
321 int shmid;
322 void *shmaddr;
323
324 shmid = shmget(IPC_PRIVATE, getpagesize(), SHM_R | SHM_W);
325 if (shmid < 0) {
326 perror("shmget");
327 exit(1);
328 }
329
330 shmaddr = shmat(shmid, NULL, 0);
331 if (shmaddr == (char *)-1) {
332 perror("shmat");
333 shmctl(shmid, IPC_RMID, NULL);
334 exit(1);
335 }
336
337 shmctl(shmid, IPC_RMID, NULL);
338
339 m1 = shmaddr;
340 m2 = shmaddr + sizeof(*m1);
341 }
342
343 *m1 = 0;
344 *m2 = 0;
345
346 mutex_lock(m1);
347 mutex_lock(m2);
348}
349
350static void *futex_thread1(void *arg)
351{
352 signal(SIGALRM, sigalrm_handler);
353 alarm(1);
354
355 while (1) {
356 mutex_lock(m2);
357 mutex_unlock(m1);
358
359 iterations += 2;
360 }
361
362 return NULL;
363}
364
365static void *futex_thread2(void *arg)
366{
367 while (1) {
368 mutex_unlock(m2);
369 mutex_lock(m1);
370 }
371
372 return NULL;
373}
374
375static struct actions futex_actions = {
376 .setup = futex_setup,
377 .thread1 = futex_thread1,
378 .thread2 = futex_thread2,
379};
380
381static struct option options[] = {
382 { "test", required_argument, 0, 't' },
383 { "process", no_argument, &processes, 1 },
384 { "timeout", required_argument, 0, 's' },
385 { "vdso", no_argument, &touch_vdso, 1 },
386 { "no-fp", no_argument, &touch_fp, 0 },
387#ifdef __powerpc__
388 { "no-altivec", no_argument, &touch_altivec, 0 },
389#endif
390 { "no-vector", no_argument, &touch_vector, 0 },
391 { 0, },
392};
393
394static void usage(void)
395{
396 fprintf(stderr, "Usage: context_switch2 <options> CPU1 CPU2\n\n");
397 fprintf(stderr, "\t\t--test=X\tpipe, futex or yield (default)\n");
398 fprintf(stderr, "\t\t--process\tUse processes (default threads)\n");
399 fprintf(stderr, "\t\t--timeout=X\tDuration in seconds to run (default 30)\n");
400 fprintf(stderr, "\t\t--vdso\t\ttouch VDSO\n");
401 fprintf(stderr, "\t\t--no-fp\t\tDon't touch FP\n");
402#ifdef __powerpc__
403 fprintf(stderr, "\t\t--no-altivec\tDon't touch altivec\n");
404#endif
405 fprintf(stderr, "\t\t--no-vector\tDon't touch vector\n");
406}
407
408int main(int argc, char *argv[])
409{
410 signed char c;
411 struct actions *actions = &yield_actions;
412 int cpu1;
413 int cpu2;
414 static void (*start_fn)(void *(*fn)(void *), void *arg, unsigned long cpu);
415
416 while (1) {
417 int option_index = 0;
418
419 c = getopt_long(argc, argv, "", options, &option_index);
420
421 if (c == -1)
422 break;
423
424 switch (c) {
425 case 0:
426 if (options[option_index].flag != 0)
427 break;
428
429 usage();
430 exit(1);
431 break;
432
433 case 't':
434 if (!strcmp(optarg, "pipe")) {
435 actions = &pipe_actions;
436 } else if (!strcmp(optarg, "yield")) {
437 actions = &yield_actions;
438 } else if (!strcmp(optarg, "futex")) {
439 actions = &futex_actions;
440 } else {
441 usage();
442 exit(1);
443 }
444 break;
445
446 case 's':
447 timeout = atoi(optarg);
448 break;
449
450 default:
451 usage();
452 exit(1);
453 }
454 }
455
456 if (processes)
457 start_fn = start_process_on;
458 else
459 start_fn = start_thread_on;
460
461 if (((argc - optind) != 2)) {
462 cpu1 = cpu2 = pick_online_cpu();
463 } else {
464 cpu1 = atoi(argv[optind++]);
465 cpu2 = atoi(argv[optind++]);
466 }
467
468 printf("Using %s with ", processes ? "processes" : "threads");
469
470 if (actions == &pipe_actions)
471 printf("pipe");
472 else if (actions == &yield_actions)
473 printf("yield");
474 else
475 printf("futex");
476
477 printf(" on cpus %d/%d touching FP:%s altivec:%s vector:%s vdso:%s\n",
478 cpu1, cpu2, touch_fp ? "yes" : "no", touch_altivec ? "yes" : "no",
479 touch_vector ? "yes" : "no", touch_vdso ? "yes" : "no");
480
481
482 setpgid(getpid(), getpid());
483
484 signal(SIGUSR1, sigusr1_handler);
485
486 actions->setup(cpu1, cpu2);
487
488 start_fn(actions->thread1, NULL, cpu1);
489 start_fn(actions->thread2, NULL, cpu2);
490
491 while (1)
492 sleep(3600);
493
494 return 0;
495}
496
