tools/testing/selftests/powerpc/benchmarks/context_switch.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * Context switch microbenchmark.
   4  *
   5  * Copyright (C) 2015 Anton Blanchard <anton@au.ibm.com>, IBM
   6  */
   7
   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/sysinfo.h>
  23 #include <sys/types.h>
  24 #include <sys/shm.h>
  25 #include <linux/futex.h>
  26 #ifdef __powerpc__
  27 #include <altivec.h>
  28 #endif
  29 #include "utils.h"
  30
  31 static unsigned int timeout = 30;
  32
  33 static int touch_vdso;
  34 struct timeval tv;
  35
  36 static int touch_fp = 1;
  37 double fp;
  38
  39 static int touch_vector = 1;
  40 vector int a, b, c;
  41
  42 #ifdef __powerpc__
  43 static int touch_altivec = 1;
  44
  45 /*
  46  * Note: LTO (Link Time Optimisation) doesn't play well with this function
  47  * attribute. Be very careful enabling LTO for this test.
  48  */
  49 static void __attribute__((__target__("no-vsx"))) altivec_touch_fn(void)
  50 {
  51         c = a + b;
  52 }
  53 #endif
  54
  55 static void touch(void)
  56 {
  57         if (touch_vdso)
  58                 gettimeofday(&tv, NULL);
  59
  60         if (touch_fp)
  61                 fp += 0.1;
  62
  63 #ifdef __powerpc__
  64         if (touch_altivec)
  65                 altivec_touch_fn();
  66 #endif
  67
  68         if (touch_vector)
  69                 c = a + b;
  70
  71         asm volatile("# %0 %1 %2": : "r"(&tv), "r"(&fp), "r"(&c));
  72 }
  73
  74 static void start_thread_on(void *(*fn)(void *), void *arg, unsigned long cpu)
  75 {
  76         int rc;
  77         pthread_t tid;
  78         cpu_set_t cpuset;
  79         pthread_attr_t attr;
  80
  81         CPU_ZERO(&cpuset);
  82         CPU_SET(cpu, &cpuset);
  83
  84         rc = pthread_attr_init(&attr);
  85         if (rc) {
  86                 errno = rc;
  87                 perror("pthread_attr_init");
  88                 exit(1);
  89         }
  90
  91         rc = pthread_attr_setaffinity_np(&attr, sizeof(cpu_set_t), &cpuset);
  92         if (rc) {
  93                 errno = rc;
  94                 perror("pthread_attr_setaffinity_np");
  95                 exit(1);
  96         }
  97
  98         rc = pthread_create(&tid, &attr, fn, arg);
  99         if (rc) {
 100                 errno = rc;
 101                 perror("pthread_create");
 102                 exit(1);
 103         }
 104 }
 105
 106 static void start_process_on(void *(*fn)(void *), void *arg, unsigned long cpu)
 107 {
 108         int pid, ncpus;
 109         cpu_set_t *cpuset;
 110         size_t size;
 111
 112         pid = fork();
 113         if (pid == -1) {
 114                 perror("fork");
 115                 exit(1);
 116         }
 117
 118         if (pid)
 119                 return;
 120
 121         ncpus = get_nprocs();
 122         size = CPU_ALLOC_SIZE(ncpus);
 123         cpuset = CPU_ALLOC(ncpus);
 124         if (!cpuset) {
 125                 perror("malloc");
 126                 exit(1);
 127         }
 128         CPU_ZERO_S(size, cpuset);
 129         CPU_SET_S(cpu, size, cpuset);
 130
 131         if (sched_setaffinity(0, size, cpuset)) {
 132                 perror("sched_setaffinity");
 133                 CPU_FREE(cpuset);
 134                 exit(1);
 135         }
 136
 137         CPU_FREE(cpuset);
 138         fn(arg);
 139
 140         exit(0);
 141 }
 142
 143 static unsigned long iterations;
 144 static unsigned long iterations_prev;
 145
 146 static void sigalrm_handler(int junk)
 147 {
 148         unsigned long i = iterations;
 149
 150         printf("%ld\n", i - iterations_prev);
 151         iterations_prev = i;
 152
 153         if (--timeout == 0)
 154                 kill(0, SIGUSR1);
 155
 156         alarm(1);
 157 }
 158
 159 static void sigusr1_handler(int junk)
 160 {
 161         exit(0);
 162 }
 163
 164 struct actions {
 165         void (*setup)(int, int);
 166         void *(*thread1)(void *);
 167         void *(*thread2)(void *);
 168 };
 169
 170 #define READ 0
 171 #define WRITE 1
 172
 173 static int pipe_fd1[2];
 174 static int pipe_fd2[2];
 175
 176 static void pipe_setup(int cpu1, int cpu2)
 177 {
 178         if (pipe(pipe_fd1) || pipe(pipe_fd2))
 179                 exit(1);
 180 }
 181
 182 static void *pipe_thread1(void *arg)
 183 {
 184         signal(SIGALRM, sigalrm_handler);
 185         alarm(1);
 186
 187         while (1) {
 188                 assert(read(pipe_fd1[READ], &c, 1) == 1);
 189                 touch();
 190
 191                 assert(write(pipe_fd2[WRITE], &c, 1) == 1);
 192                 touch();
 193
 194                 iterations += 2;
 195         }
 196
 197         return NULL;
 198 }
 199
 200 static void *pipe_thread2(void *arg)
 201 {
 202         while (1) {
 203                 assert(write(pipe_fd1[WRITE], &c, 1) == 1);
 204                 touch();
 205
 206                 assert(read(pipe_fd2[READ], &c, 1) == 1);
 207                 touch();
 208         }
 209
 210         return NULL;
 211 }
 212
 213 static struct actions pipe_actions = {
 214         .setup = pipe_setup,
 215         .thread1 = pipe_thread1,
 216         .thread2 = pipe_thread2,
 217 };
 218
 219 static void yield_setup(int cpu1, int cpu2)
 220 {
 221         if (cpu1 != cpu2) {
 222                 fprintf(stderr, "Both threads must be on the same CPU for yield test\n");
 223                 exit(1);
 224         }
 225 }
 226
 227 static void *yield_thread1(void *arg)
 228 {
 229         signal(SIGALRM, sigalrm_handler);
 230         alarm(1);
 231
 232         while (1) {
 233                 sched_yield();
 234                 touch();
 235
 236                 iterations += 2;
 237         }
 238
 239         return NULL;
 240 }
 241
 242 static void *yield_thread2(void *arg)
 243 {
 244         while (1) {
 245                 sched_yield();
 246                 touch();
 247         }
 248
 249         return NULL;
 250 }
 251
 252 static struct actions yield_actions = {
 253         .setup = yield_setup,
 254         .thread1 = yield_thread1,
 255         .thread2 = yield_thread2,
 256 };
 257
 258 static long sys_futex(void *addr1, int op, int val1, struct timespec *timeout,
 259                       void *addr2, int val3)
 260 {
 261         return syscall(SYS_futex, addr1, op, val1, timeout, addr2, val3);
 262 }
 263
 264 static unsigned long cmpxchg(unsigned long *p, unsigned long expected,
 265                              unsigned long desired)
 266 {
 267         unsigned long exp = expected;
 268
 269         __atomic_compare_exchange_n(p, &exp, desired, 0,
 270                                     __ATOMIC_SEQ_CST, __ATOMIC_SEQ_CST);
 271         return exp;
 272 }
 273
 274 static unsigned long xchg(unsigned long *p, unsigned long val)
 275 {
 276         return __atomic_exchange_n(p, val, __ATOMIC_SEQ_CST);
 277 }
 278
 279 static int processes;
 280
 281 static int mutex_lock(unsigned long *m)
 282 {
 283         int c;
 284         int flags = FUTEX_WAIT;
 285         if (!processes)
 286                 flags |= FUTEX_PRIVATE_FLAG;
 287
 288         c = cmpxchg(m, 0, 1);
 289         if (!c)
 290                 return 0;
 291
 292         if (c == 1)
 293                 c = xchg(m, 2);
 294
 295         while (c) {
 296                 sys_futex(m, flags, 2, NULL, NULL, 0);
 297                 c = xchg(m, 2);
 298         }
 299
 300         return 0;
 301 }
 302
 303 static int mutex_unlock(unsigned long *m)
 304 {
 305         int flags = FUTEX_WAKE;
 306         if (!processes)
 307                 flags |= FUTEX_PRIVATE_FLAG;
 308
 309         if (*m == 2)
 310                 *m = 0;
 311         else if (xchg(m, 0) == 1)
 312                 return 0;
 313
 314         sys_futex(m, flags, 1, NULL, NULL, 0);
 315
 316         return 0;
 317 }
 318
 319 static unsigned long *m1, *m2;
 320
 321 static void futex_setup(int cpu1, int cpu2)
 322 {
 323         if (!processes) {
 324                 static unsigned long _m1, _m2;
 325                 m1 = &_m1;
 326                 m2 = &_m2;
 327         } else {
 328                 int shmid;
 329                 void *shmaddr;
 330
 331                 shmid = shmget(IPC_PRIVATE, getpagesize(), SHM_R | SHM_W);
 332                 if (shmid < 0) {
 333                         perror("shmget");
 334                         exit(1);
 335                 }
 336
 337                 shmaddr = shmat(shmid, NULL, 0);
 338                 if (shmaddr == (char *)-1) {
 339                         perror("shmat");
 340                         shmctl(shmid, IPC_RMID, NULL);
 341                         exit(1);
 342                 }
 343
 344                 shmctl(shmid, IPC_RMID, NULL);
 345
 346                 m1 = shmaddr;
 347                 m2 = shmaddr + sizeof(*m1);
 348         }
 349
 350         *m1 = 0;
 351         *m2 = 0;
 352
 353         mutex_lock(m1);
 354         mutex_lock(m2);
 355 }
 356
 357 static void *futex_thread1(void *arg)
 358 {
 359         signal(SIGALRM, sigalrm_handler);
 360         alarm(1);
 361
 362         while (1) {
 363                 mutex_lock(m2);
 364                 mutex_unlock(m1);
 365
 366                 iterations += 2;
 367         }
 368
 369         return NULL;
 370 }
 371
 372 static void *futex_thread2(void *arg)
 373 {
 374         while (1) {
 375                 mutex_unlock(m2);
 376                 mutex_lock(m1);
 377         }
 378
 379         return NULL;
 380 }
 381
 382 static struct actions futex_actions = {
 383         .setup = futex_setup,
 384         .thread1 = futex_thread1,
 385         .thread2 = futex_thread2,
 386 };
 387
 388 static struct option options[] = {
 389         { "test", required_argument, 0, 't' },
 390         { "process", no_argument, &processes, 1 },
 391         { "timeout", required_argument, 0, 's' },
 392         { "vdso", no_argument, &touch_vdso, 1 },
 393         { "no-fp", no_argument, &touch_fp, 0 },
 394 #ifdef __powerpc__
 395         { "no-altivec", no_argument, &touch_altivec, 0 },
 396 #endif
 397         { "no-vector", no_argument, &touch_vector, 0 },
 398         { 0, },
 399 };
 400
 401 static void usage(void)
 402 {
 403         fprintf(stderr, "Usage: context_switch2 <options> CPU1 CPU2\n\n");
 404         fprintf(stderr, "\t\t--test=X\tpipe, futex or yield (default)\n");
 405         fprintf(stderr, "\t\t--process\tUse processes (default threads)\n");
 406         fprintf(stderr, "\t\t--timeout=X\tDuration in seconds to run (default 30)\n");
 407         fprintf(stderr, "\t\t--vdso\t\ttouch VDSO\n");
 408         fprintf(stderr, "\t\t--no-fp\t\tDon't touch FP\n");
 409 #ifdef __powerpc__
 410         fprintf(stderr, "\t\t--no-altivec\tDon't touch altivec\n");
 411 #endif
 412         fprintf(stderr, "\t\t--no-vector\tDon't touch vector\n");
 413 }
 414
 415 int main(int argc, char *argv[])
 416 {
 417         signed char c;
 418         struct actions *actions = &yield_actions;
 419         int cpu1;
 420         int cpu2;
 421         static void (*start_fn)(void *(*fn)(void *), void *arg, unsigned long cpu);
 422
 423         while (1) {
 424                 int option_index = 0;
 425
 426                 c = getopt_long(argc, argv, "", options, &option_index);
 427
 428                 if (c == -1)
 429                         break;
 430
 431                 switch (c) {
 432                 case 0:
 433                         if (options[option_index].flag != 0)
 434                                 break;
 435
 436                         usage();
 437                         exit(1);
 438                         break;
 439
 440                 case 't':
 441                         if (!strcmp(optarg, "pipe")) {
 442                                 actions = &pipe_actions;
 443                         } else if (!strcmp(optarg, "yield")) {
 444                                 actions = &yield_actions;
 445                         } else if (!strcmp(optarg, "futex")) {
 446                                 actions = &futex_actions;
 447                         } else {
 448                                 usage();
 449                                 exit(1);
 450                         }
 451                         break;
 452
 453                 case 's':
 454                         timeout = atoi(optarg);
 455                         break;
 456
 457                 default:
 458                         usage();
 459                         exit(1);
 460                 }
 461         }
 462
 463         if (processes)
 464                 start_fn = start_process_on;
 465         else
 466                 start_fn = start_thread_on;
 467
 468         if (((argc - optind) != 2)) {
 469                 cpu1 = cpu2 = pick_online_cpu();
 470         } else {
 471                 cpu1 = atoi(argv[optind++]);
 472                 cpu2 = atoi(argv[optind++]);
 473         }
 474
 475         printf("Using %s with ", processes ? "processes" : "threads");
 476
 477         if (actions == &pipe_actions)
 478                 printf("pipe");
 479         else if (actions == &yield_actions)
 480                 printf("yield");
 481         else
 482                 printf("futex");
 483
 484         if (!have_hwcap(PPC_FEATURE_HAS_ALTIVEC))
 485                 touch_altivec = 0;
 486
 487         if (!have_hwcap(PPC_FEATURE_HAS_VSX))
 488                 touch_vector = 0;
 489
 490         printf(" on cpus %d/%d touching FP:%s altivec:%s vector:%s vdso:%s\n",
 491                cpu1, cpu2, touch_fp ?  "yes" : "no", touch_altivec ? "yes" : "no",
 492                touch_vector ? "yes" : "no", touch_vdso ? "yes" : "no");
 493
 494         /* Create a new process group so we can signal everyone for exit */
 495         setpgid(getpid(), getpid());
 496
 497         signal(SIGUSR1, sigusr1_handler);
 498
 499         actions->setup(cpu1, cpu2);
 500
 501         start_fn(actions->thread1, NULL, cpu1);
 502         start_fn(actions->thread2, NULL, cpu2);
 503
 504         while (1)
 505                 sleep(3600);
 506
 507         return 0;
 508 }