idletime.c

   1 #include <math.h>
   2 #include "fio.h"
   3 #include "json.h"
   4 #include "idletime.h"
   5
   6 static volatile struct idle_prof_common ipc;
   7
   8 /*
   9  * Get time to complete an unit work on a particular cpu.
  10  * The minimum number in CALIBRATE_RUNS runs is returned.
  11  */
  12 static double calibrate_unit(unsigned char *data)
  13 {
  14         unsigned long t, i, j, k;
  15         struct timespec tps;
  16         double tunit = 0.0;
  17
  18         for (i = 0; i < CALIBRATE_RUNS; i++) {
  19
  20                 fio_gettime(&tps, NULL);
  21                 /* scale for less variance */
  22                 for (j = 0; j < CALIBRATE_SCALE; j++) {
  23                         /* unit of work */
  24                         for (k=0; k < page_size; k++) {
  25                                 data[(k + j) % page_size] = k % 256;
  26                                 /*
  27                                  * we won't see STOP here. this is to match
  28                                  * the same statement in the profiling loop.
  29                                  */
  30                                 if (ipc.status == IDLE_PROF_STATUS_PROF_STOP)
  31                                         return 0.0;
  32                         }
  33                 }
  34
  35                 t = utime_since_now(&tps);
  36                 if (!t)
  37                         continue;
  38
  39                 /* get the minimum time to complete CALIBRATE_SCALE units */
  40                 if ((i == 0) || ((double)t < tunit))
  41                         tunit = (double)t;
  42         }
  43
  44         return tunit / CALIBRATE_SCALE;
  45 }
  46
  47 static void free_cpu_affinity(struct idle_prof_thread *ipt)
  48 {
  49 #if defined(FIO_HAVE_CPU_AFFINITY)
  50         fio_cpuset_exit(&ipt->cpu_mask);
  51 #endif
  52 }
  53
  54 static int set_cpu_affinity(struct idle_prof_thread *ipt)
  55 {
  56 #if defined(FIO_HAVE_CPU_AFFINITY)
  57         if (fio_cpuset_init(&ipt->cpu_mask)) {
  58                 log_err("fio: cpuset init failed\n");
  59                 return -1;
  60         }
  61
  62         fio_cpu_set(&ipt->cpu_mask, ipt->cpu);
  63
  64         if (fio_setaffinity(gettid(), ipt->cpu_mask)) {
  65                 log_err("fio: fio_setaffinity failed\n");
  66                 fio_cpuset_exit(&ipt->cpu_mask);
  67                 return -1;
  68         }
  69
  70         return 0;
  71 #else
  72         log_err("fio: fio_setaffinity not supported\n");
  73         return -1;
  74 #endif
  75 }
  76
  77 static void *idle_prof_thread_fn(void *data)
  78 {
  79         int retval;
  80         unsigned long j, k;
  81         struct idle_prof_thread *ipt = data;
  82
  83         /* wait for all threads are spawned */
  84         pthread_mutex_lock(&ipt->init_lock);
  85
  86         /* exit if any other thread failed to start */
  87         if (ipc.status == IDLE_PROF_STATUS_ABORT) {
  88                 pthread_mutex_unlock(&ipt->init_lock);
  89                 return NULL;
  90         }
  91
  92         retval = set_cpu_affinity(ipt);
  93         if (retval == -1) {
  94                 ipt->state = TD_EXITED;
  95                 pthread_mutex_unlock(&ipt->init_lock);
  96                 return NULL;
  97         }
  98
  99         ipt->cali_time = calibrate_unit(ipt->data);
 100
 101         /* delay to set IDLE class till now for better calibration accuracy */
 102 #if defined(CONFIG_SCHED_IDLE)
 103         if ((retval = fio_set_sched_idle()))
 104                 log_err("fio: fio_set_sched_idle failed\n");
 105 #else
 106         retval = -1;
 107         log_err("fio: fio_set_sched_idle not supported\n");
 108 #endif
 109         if (retval == -1) {
 110                 ipt->state = TD_EXITED;
 111                 pthread_mutex_unlock(&ipt->init_lock);
 112                 goto do_exit;
 113         }
 114
 115         ipt->state = TD_INITIALIZED;
 116
 117         /* signal the main thread that calibration is done */
 118         pthread_cond_signal(&ipt->cond);
 119         pthread_mutex_unlock(&ipt->init_lock);
 120
 121         /* wait for other calibration to finish */
 122         pthread_mutex_lock(&ipt->start_lock);
 123
 124         /* exit if other threads failed to initialize */
 125         if (ipc.status == IDLE_PROF_STATUS_ABORT) {
 126                 pthread_mutex_unlock(&ipt->start_lock);
 127                 goto do_exit;
 128         }
 129
 130         /* exit if we are doing calibration only */
 131         if (ipc.status == IDLE_PROF_STATUS_CALI_STOP) {
 132                 pthread_mutex_unlock(&ipt->start_lock);
 133                 goto do_exit;
 134         }
 135
 136         fio_gettime(&ipt->tps, NULL);
 137         ipt->state = TD_RUNNING;
 138
 139         j = 0;
 140         while (1) {
 141                 for (k = 0; k < page_size; k++) {
 142                         ipt->data[(k + j) % page_size] = k % 256;
 143                         if (ipc.status == IDLE_PROF_STATUS_PROF_STOP) {
 144                                 fio_gettime(&ipt->tpe, NULL);
 145                                 goto idle_prof_done;
 146                         }
 147                 }
 148                 j++;
 149         }
 150
 151 idle_prof_done:
 152
 153         ipt->loops = j + (double) k / page_size;
 154         ipt->state = TD_EXITED;
 155         pthread_mutex_unlock(&ipt->start_lock);
 156
 157 do_exit:
 158         free_cpu_affinity(ipt);
 159         return NULL;
 160 }
 161
 162 /* calculate mean and standard deviation to complete an unit of work */
 163 static void calibration_stats(void)
 164 {
 165         int i;
 166         double sum = 0.0, var = 0.0;
 167         struct idle_prof_thread *ipt;
 168
 169         for (i = 0; i < ipc.nr_cpus; i++) {
 170                 ipt = &ipc.ipts[i];
 171                 sum += ipt->cali_time;
 172         }
 173
 174         ipc.cali_mean = sum/ipc.nr_cpus;
 175
 176         for (i = 0; i < ipc.nr_cpus; i++) {
 177                 ipt = &ipc.ipts[i];
 178                 var += pow(ipt->cali_time-ipc.cali_mean, 2);
 179         }
 180
 181         ipc.cali_stddev = sqrt(var/(ipc.nr_cpus-1));
 182 }
 183
 184 void fio_idle_prof_init(void)
 185 {
 186         int i, ret;
 187         struct timespec ts;
 188         pthread_attr_t tattr;
 189         pthread_condattr_t cattr;
 190         struct idle_prof_thread *ipt;
 191
 192         ipc.nr_cpus = cpus_configured();
 193         ipc.status = IDLE_PROF_STATUS_OK;
 194
 195         if (ipc.opt == IDLE_PROF_OPT_NONE)
 196                 return;
 197
 198         ret = pthread_condattr_init(&cattr);
 199         assert(ret == 0);
 200 #ifdef CONFIG_PTHREAD_CONDATTR_SETCLOCK
 201         ret = pthread_condattr_setclock(&cattr, CLOCK_MONOTONIC);
 202         assert(ret == 0);
 203 #endif
 204
 205         if ((ret = pthread_attr_init(&tattr))) {
 206                 log_err("fio: pthread_attr_init %s\n", strerror(ret));
 207                 return;
 208         }
 209         if ((ret = pthread_attr_setscope(&tattr, PTHREAD_SCOPE_SYSTEM))) {
 210                 log_err("fio: pthread_attr_setscope %s\n", strerror(ret));
 211                 return;
 212         }
 213
 214         ipc.ipts = malloc(ipc.nr_cpus * sizeof(struct idle_prof_thread));
 215         if (!ipc.ipts) {
 216                 log_err("fio: malloc failed\n");
 217                 return;
 218         }
 219
 220         ipc.buf = malloc(ipc.nr_cpus * page_size);
 221         if (!ipc.buf) {
 222                 log_err("fio: malloc failed\n");
 223                 free(ipc.ipts);
 224                 return;
 225         }
 226
 227         /*
 228          * profiling aborts on any single thread failure since the
 229          * result won't be accurate if any cpu is not used.
 230          */
 231         for (i = 0; i < ipc.nr_cpus; i++) {
 232                 ipt = &ipc.ipts[i];
 233
 234                 ipt->cpu = i;
 235                 ipt->state = TD_NOT_CREATED;
 236                 ipt->data = (unsigned char *)(ipc.buf + page_size * i);
 237
 238                 if ((ret = pthread_mutex_init(&ipt->init_lock, NULL))) {
 239                         ipc.status = IDLE_PROF_STATUS_ABORT;
 240                         log_err("fio: pthread_mutex_init %s\n", strerror(ret));
 241                         break;
 242                 }
 243
 244                 if ((ret = pthread_mutex_init(&ipt->start_lock, NULL))) {
 245                         ipc.status = IDLE_PROF_STATUS_ABORT;
 246                         log_err("fio: pthread_mutex_init %s\n", strerror(ret));
 247                         break;
 248                 }
 249
 250                 if ((ret = pthread_cond_init(&ipt->cond, &cattr))) {
 251                         ipc.status = IDLE_PROF_STATUS_ABORT;
 252                         log_err("fio: pthread_cond_init %s\n", strerror(ret));
 253                         break;
 254                 }
 255
 256                 /* make sure all threads are spawned before they start */
 257                 pthread_mutex_lock(&ipt->init_lock);
 258
 259                 /* make sure all threads finish init before profiling starts */
 260                 pthread_mutex_lock(&ipt->start_lock);
 261
 262                 if ((ret = pthread_create(&ipt->thread, &tattr, idle_prof_thread_fn, ipt))) {
 263                         ipc.status = IDLE_PROF_STATUS_ABORT;
 264                         log_err("fio: pthread_create %s\n", strerror(ret));
 265                         break;
 266                 } else
 267                         ipt->state = TD_CREATED;
 268
 269                 if ((ret = pthread_detach(ipt->thread))) {
 270                         /* log error and let the thread spin */
 271                         log_err("fio: pthread_detach %s\n", strerror(ret));
 272                 }
 273         }
 274
 275         /*
 276          * let good threads continue so that they can exit
 277          * if errors on other threads occurred previously.
 278          */
 279         for (i = 0; i < ipc.nr_cpus; i++) {
 280                 ipt = &ipc.ipts[i];
 281                 pthread_mutex_unlock(&ipt->init_lock);
 282         }
 283
 284         if (ipc.status == IDLE_PROF_STATUS_ABORT)
 285                 return;
 286
 287         /* wait for calibration to finish */
 288         for (i = 0; i < ipc.nr_cpus; i++) {
 289                 ipt = &ipc.ipts[i];
 290                 pthread_mutex_lock(&ipt->init_lock);
 291                 while ((ipt->state != TD_EXITED) &&
 292                        (ipt->state!=TD_INITIALIZED)) {
 293 #ifdef CONFIG_PTHREAD_CONDATTR_SETCLOCK
 294                         clock_gettime(CLOCK_MONOTONIC, &ts);
 295 #else
 296                         clock_gettime(CLOCK_REALTIME, &ts);
 297 #endif
 298                         ts.tv_sec += 1;
 299                         pthread_cond_timedwait(&ipt->cond, &ipt->init_lock, &ts);
 300                 }
 301                 pthread_mutex_unlock(&ipt->init_lock);
 302
 303                 /*
 304                  * any thread failed to initialize would abort other threads
 305                  * later after fio_idle_prof_start.
 306                  */
 307                 if (ipt->state == TD_EXITED)
 308                         ipc.status = IDLE_PROF_STATUS_ABORT;
 309         }
 310
 311         if (ipc.status != IDLE_PROF_STATUS_ABORT)
 312                 calibration_stats();
 313         else
 314                 ipc.cali_mean = ipc.cali_stddev = 0.0;
 315
 316         if (ipc.opt == IDLE_PROF_OPT_CALI)
 317                 ipc.status = IDLE_PROF_STATUS_CALI_STOP;
 318 }
 319
 320 void fio_idle_prof_start(void)
 321 {
 322         int i;
 323         struct idle_prof_thread *ipt;
 324
 325         if (ipc.opt == IDLE_PROF_OPT_NONE)
 326                 return;
 327
 328         /* unlock regardless abort is set or not */
 329         for (i = 0; i < ipc.nr_cpus; i++) {
 330                 ipt = &ipc.ipts[i];
 331                 pthread_mutex_unlock(&ipt->start_lock);
 332         }
 333 }
 334
 335 void fio_idle_prof_stop(void)
 336 {
 337         int i;
 338         uint64_t runt;
 339         struct timespec ts;
 340         struct idle_prof_thread *ipt;
 341
 342         if (ipc.opt == IDLE_PROF_OPT_NONE)
 343                 return;
 344
 345         if (ipc.opt == IDLE_PROF_OPT_CALI)
 346                 return;
 347
 348         ipc.status = IDLE_PROF_STATUS_PROF_STOP;
 349
 350         /* wait for all threads to exit from profiling */
 351         for (i = 0; i < ipc.nr_cpus; i++) {
 352                 ipt = &ipc.ipts[i];
 353                 pthread_mutex_lock(&ipt->start_lock);
 354                 while ((ipt->state != TD_EXITED) &&
 355                        (ipt->state!=TD_NOT_CREATED)) {
 356                         fio_gettime(&ts, NULL);
 357                         ts.tv_sec += 1;
 358                         /* timed wait in case a signal is not received */
 359                         pthread_cond_timedwait(&ipt->cond, &ipt->start_lock, &ts);
 360                 }
 361                 pthread_mutex_unlock(&ipt->start_lock);
 362
 363                 /* calculate idleness */
 364                 if (ipc.cali_mean != 0.0) {
 365                         runt = utime_since(&ipt->tps, &ipt->tpe);
 366                         if (runt)
 367                                 ipt->idleness = ipt->loops * ipc.cali_mean / runt;
 368                         else
 369                                 ipt->idleness = 0.0;
 370                 } else
 371                         ipt->idleness = 0.0;
 372         }
 373
 374         /*
 375          * memory allocations are freed via explicit fio_idle_prof_cleanup
 376          * after profiling stats are collected by apps.
 377          */
 378 }
 379
 380 /*
 381  * return system idle percentage when cpu is -1;
 382  * return one cpu idle percentage otherwise.
 383  */
 384 static double fio_idle_prof_cpu_stat(int cpu)
 385 {
 386         int i, nr_cpus = ipc.nr_cpus;
 387         struct idle_prof_thread *ipt;
 388         double p = 0.0;
 389
 390         if (ipc.opt == IDLE_PROF_OPT_NONE)
 391                 return 0.0;
 392
 393         if ((cpu >= nr_cpus) || (cpu < -1)) {
 394                 log_err("fio: idle profiling invalid cpu index\n");
 395                 return 0.0;
 396         }
 397
 398         if (cpu == -1) {
 399                 for (i = 0; i < nr_cpus; i++) {
 400                         ipt = &ipc.ipts[i];
 401                         p += ipt->idleness;
 402                 }
 403                 p /= nr_cpus;
 404         } else {
 405                 ipt = &ipc.ipts[cpu];
 406                 p = ipt->idleness;
 407         }
 408
 409         return p * 100.0;
 410 }
 411
 412 void fio_idle_prof_cleanup(void)
 413 {
 414         if (ipc.ipts) {
 415                 free(ipc.ipts);
 416                 ipc.ipts = NULL;
 417         }
 418
 419         if (ipc.buf) {
 420                 free(ipc.buf);
 421                 ipc.buf = NULL;
 422         }
 423 }
 424
 425 int fio_idle_prof_parse_opt(const char *args)
 426 {
 427         ipc.opt = IDLE_PROF_OPT_NONE; /* default */
 428
 429         if (!args) {
 430                 log_err("fio: empty idle-prof option string\n");
 431                 return -1;
 432         }
 433
 434 #if defined(FIO_HAVE_CPU_AFFINITY) && defined(CONFIG_SCHED_IDLE)
 435         if (strcmp("calibrate", args) == 0) {
 436                 ipc.opt = IDLE_PROF_OPT_CALI;
 437                 fio_idle_prof_init();
 438                 fio_idle_prof_start();
 439                 fio_idle_prof_stop();
 440                 show_idle_prof_stats(FIO_OUTPUT_NORMAL, NULL, NULL);
 441                 return 1;
 442         } else if (strcmp("system", args) == 0) {
 443                 ipc.opt = IDLE_PROF_OPT_SYSTEM;
 444                 return 0;
 445         } else if (strcmp("percpu", args) == 0) {
 446                 ipc.opt = IDLE_PROF_OPT_PERCPU;
 447                 return 0;
 448         } else {
 449                 log_err("fio: incorrect idle-prof option: %s\n", args);
 450                 return -1;
 451         }
 452 #else
 453         log_err("fio: idle-prof not supported on this platform\n");
 454         return -1;
 455 #endif
 456 }
 457
 458 void show_idle_prof_stats(int output, struct json_object *parent,
 459                           struct buf_output *out)
 460 {
 461         int i, nr_cpus = ipc.nr_cpus;
 462         struct json_object *tmp;
 463         char s[MAX_CPU_STR_LEN];
 464
 465         if (output == FIO_OUTPUT_NORMAL) {
 466                 if (ipc.opt > IDLE_PROF_OPT_CALI)
 467                         log_buf(out, "\nCPU idleness:\n");
 468                 else if (ipc.opt == IDLE_PROF_OPT_CALI)
 469                         log_buf(out, "CPU idleness:\n");
 470
 471                 if (ipc.opt >= IDLE_PROF_OPT_SYSTEM)
 472                         log_buf(out, "  system: %3.2f%%\n", fio_idle_prof_cpu_stat(-1));
 473
 474                 if (ipc.opt == IDLE_PROF_OPT_PERCPU) {
 475                         log_buf(out, "  percpu: %3.2f%%", fio_idle_prof_cpu_stat(0));
 476                         for (i = 1; i < nr_cpus; i++)
 477                                 log_buf(out, ", %3.2f%%", fio_idle_prof_cpu_stat(i));
 478                         log_buf(out, "\n");
 479                 }
 480
 481                 if (ipc.opt >= IDLE_PROF_OPT_CALI) {
 482                         log_buf(out, "  unit work: mean=%3.2fus,", ipc.cali_mean);
 483                         log_buf(out, " stddev=%3.2f\n", ipc.cali_stddev);
 484                 }
 485
 486                 return;
 487         }
 488
 489         if ((ipc.opt != IDLE_PROF_OPT_NONE) && (output & FIO_OUTPUT_JSON)) {
 490                 if (!parent)
 491                         return;
 492
 493                 tmp = json_create_object();
 494                 if (!tmp)
 495                         return;
 496
 497                 json_object_add_value_object(parent, "cpu_idleness", tmp);
 498                 json_object_add_value_float(tmp, "system", fio_idle_prof_cpu_stat(-1));
 499
 500                 if (ipc.opt == IDLE_PROF_OPT_PERCPU) {
 501                         for (i = 0; i < nr_cpus; i++) {
 502                                 snprintf(s, MAX_CPU_STR_LEN, "cpu-%d", i);
 503                                 json_object_add_value_float(tmp, s, fio_idle_prof_cpu_stat(i));
 504                         }
 505                 }
 506
 507                 json_object_add_value_float(tmp, "unit_mean", ipc.cali_mean);
 508                 json_object_add_value_float(tmp, "unit_stddev", ipc.cali_stddev);
 509         }
 510 }