idletime.c

   1 #include <math.h>
   2 #include "json.h"
   3 #include "idletime.h"
   4
   5 static volatile struct idle_prof_common ipc;
   6
   7 /*
   8  * Get time to complete an unit work on a particular cpu.
   9  * The minimum number in CALIBRATE_RUNS runs is returned.
  10  */
  11 static double calibrate_unit(unsigned char *data)
  12 {
  13         unsigned long t, i, j, k;
  14         struct timeval tps;
  15         double tunit = 0.0;
  16
  17         for (i = 0; i < CALIBRATE_RUNS; i++) {
  18
  19                 fio_gettime(&tps, NULL);
  20                 /* scale for less variance */
  21                 for (j = 0; j < CALIBRATE_SCALE; j++) {
  22                         /* unit of work */
  23                         for (k=0; k < page_size; k++) {
  24                                 data[(k + j) % page_size] = k % 256;
  25                                 /*
  26                                  * we won't see STOP here. this is to match
  27                                  * the same statement in the profiling loop.
  28                                  */
  29                                 if (ipc.status == IDLE_PROF_STATUS_PROF_STOP)
  30                                         return 0.0;
  31                         }
  32                 }
  33
  34                 t = utime_since_now(&tps);
  35                 if (!t)
  36                         continue;
  37
  38                 /* get the minimum time to complete CALIBRATE_SCALE units */
  39                 if ((i == 0) || ((double)t < tunit))
  40                         tunit = (double)t;
  41         }
  42
  43         return tunit / CALIBRATE_SCALE;
  44 }
  45
  46 static void free_cpu_affinity(struct idle_prof_thread *ipt)
  47 {
  48 #if defined(FIO_HAVE_CPU_AFFINITY)
  49         fio_cpuset_exit(&ipt->cpu_mask);
  50 #endif
  51 }
  52
  53 static int set_cpu_affinity(struct idle_prof_thread *ipt)
  54 {
  55 #if defined(FIO_HAVE_CPU_AFFINITY)
  56         if (fio_cpuset_init(&ipt->cpu_mask)) {
  57                 log_err("fio: cpuset init failed\n");
  58                 return -1;
  59         }
  60
  61         fio_cpu_set(&ipt->cpu_mask, ipt->cpu);
  62
  63         if (fio_setaffinity(gettid(), ipt->cpu_mask)) {
  64                 log_err("fio: fio_setaffinity failed\n");
  65                 fio_cpuset_exit(&ipt->cpu_mask);
  66                 return -1;
  67         }
  68
  69         return 0;
  70 #else
  71         log_err("fio: fio_setaffinity not supported\n");
  72         return -1;
  73 #endif
  74 }
  75
  76 static void *idle_prof_thread_fn(void *data)
  77 {
  78         int retval;
  79         unsigned long j, k;
  80         struct idle_prof_thread *ipt = data;
  81
  82         /* wait for all threads are spawned */
  83         pthread_mutex_lock(&ipt->init_lock);
  84
  85         /* exit if any other thread failed to start */
  86         if (ipc.status == IDLE_PROF_STATUS_ABORT) {
  87                 pthread_mutex_unlock(&ipt->init_lock);
  88                 return NULL;
  89         }
  90
  91         retval = set_cpu_affinity(ipt);
  92         if (retval == -1) {
  93                 ipt->state = TD_EXITED;
  94                 pthread_mutex_unlock(&ipt->init_lock);
  95                 return NULL;
  96         }
  97
  98         ipt->cali_time = calibrate_unit(ipt->data);
  99
 100         /* delay to set IDLE class till now for better calibration accuracy */
 101 #if defined(CONFIG_SCHED_IDLE)
 102         if ((retval = fio_set_sched_idle()))
 103                 log_err("fio: fio_set_sched_idle failed\n");
 104 #else
 105         retval = -1;
 106         log_err("fio: fio_set_sched_idle not supported\n");
 107 #endif
 108         if (retval == -1) {
 109                 ipt->state = TD_EXITED;
 110                 pthread_mutex_unlock(&ipt->init_lock);
 111                 goto do_exit;
 112         }
 113
 114         ipt->state = TD_INITIALIZED;
 115
 116         /* signal the main thread that calibration is done */
 117         pthread_cond_signal(&ipt->cond);
 118         pthread_mutex_unlock(&ipt->init_lock);
 119
 120         /* wait for other calibration to finish */
 121         pthread_mutex_lock(&ipt->start_lock);
 122
 123         /* exit if other threads failed to initialize */
 124         if (ipc.status == IDLE_PROF_STATUS_ABORT) {
 125                 pthread_mutex_unlock(&ipt->start_lock);
 126                 goto do_exit;
 127         }
 128
 129         /* exit if we are doing calibration only */
 130         if (ipc.status == IDLE_PROF_STATUS_CALI_STOP) {
 131                 pthread_mutex_unlock(&ipt->start_lock);
 132                 goto do_exit;
 133         }
 134
 135         fio_gettime(&ipt->tps, NULL);
 136         ipt->state = TD_RUNNING;
 137
 138         j = 0;
 139         while (1) {
 140                 for (k = 0; k < page_size; k++) {
 141                         ipt->data[(k + j) % page_size] = k % 256;
 142                         if (ipc.status == IDLE_PROF_STATUS_PROF_STOP) {
 143                                 fio_gettime(&ipt->tpe, NULL);
 144                                 goto idle_prof_done;
 145                         }
 146                 }
 147                 j++;
 148         }
 149
 150 idle_prof_done:
 151
 152         ipt->loops = j + (double) k / page_size;
 153         ipt->state = TD_EXITED;
 154         pthread_mutex_unlock(&ipt->start_lock);
 155
 156 do_exit:
 157         free_cpu_affinity(ipt);
 158         return NULL;
 159 }
 160
 161 /* calculate mean and standard deviation to complete an unit of work */
 162 static void calibration_stats(void)
 163 {
 164         int i;
 165         double sum = 0.0, var = 0.0;
 166         struct idle_prof_thread *ipt;
 167
 168         for (i = 0; i < ipc.nr_cpus; i++) {
 169                 ipt = &ipc.ipts[i];
 170                 sum += ipt->cali_time;
 171         }
 172
 173         ipc.cali_mean = sum/ipc.nr_cpus;
 174
 175         for (i = 0; i < ipc.nr_cpus; i++) {
 176                 ipt = &ipc.ipts[i];
 177                 var += pow(ipt->cali_time-ipc.cali_mean, 2);
 178         }
 179
 180         ipc.cali_stddev = sqrt(var/(ipc.nr_cpus-1));
 181 }
 182
 183 void fio_idle_prof_init(void)
 184 {
 185         int i, ret;
 186         struct timeval tp;
 187         struct timespec ts;
 188         pthread_attr_t tattr;
 189         struct idle_prof_thread *ipt;
 190
 191         ipc.nr_cpus = cpus_online();
 192         ipc.status = IDLE_PROF_STATUS_OK;
 193
 194         if (ipc.opt == IDLE_PROF_OPT_NONE)
 195                 return;
 196
 197         if ((ret = pthread_attr_init(&tattr))) {
 198                 log_err("fio: pthread_attr_init %s\n", strerror(ret));
 199                 return;
 200         }
 201         if ((ret = pthread_attr_setscope(&tattr, PTHREAD_SCOPE_SYSTEM))) {
 202                 log_err("fio: pthread_attr_setscope %s\n", strerror(ret));
 203                 return;
 204         }
 205
 206         ipc.ipts = malloc(ipc.nr_cpus * sizeof(struct idle_prof_thread));
 207         if (!ipc.ipts) {
 208                 log_err("fio: malloc failed\n");
 209                 return;
 210         }
 211
 212         ipc.buf = malloc(ipc.nr_cpus * page_size);
 213         if (!ipc.buf) {
 214                 log_err("fio: malloc failed\n");
 215                 free(ipc.ipts);
 216                 return;
 217         }
 218
 219         /*
 220          * profiling aborts on any single thread failure since the
 221          * result won't be accurate if any cpu is not used.
 222          */
 223         for (i = 0; i < ipc.nr_cpus; i++) {
 224                 ipt = &ipc.ipts[i];
 225
 226                 ipt->cpu = i;
 227                 ipt->state = TD_NOT_CREATED;
 228                 ipt->data = (unsigned char *)(ipc.buf + page_size * i);
 229
 230                 if ((ret = pthread_mutex_init(&ipt->init_lock, NULL))) {
 231                         ipc.status = IDLE_PROF_STATUS_ABORT;
 232                         log_err("fio: pthread_mutex_init %s\n", strerror(ret));
 233                         break;
 234                 }
 235
 236                 if ((ret = pthread_mutex_init(&ipt->start_lock, NULL))) {
 237                         ipc.status = IDLE_PROF_STATUS_ABORT;
 238                         log_err("fio: pthread_mutex_init %s\n", strerror(ret));
 239                         break;
 240                 }
 241
 242                 if ((ret = pthread_cond_init(&ipt->cond, NULL))) {
 243                         ipc.status = IDLE_PROF_STATUS_ABORT;
 244                         log_err("fio: pthread_cond_init %s\n", strerror(ret));
 245                         break;
 246                 }
 247
 248                 /* make sure all threads are spawned before they start */
 249                 pthread_mutex_lock(&ipt->init_lock);
 250
 251                 /* make sure all threads finish init before profiling starts */
 252                 pthread_mutex_lock(&ipt->start_lock);
 253
 254                 if ((ret = pthread_create(&ipt->thread, &tattr, idle_prof_thread_fn, ipt))) {
 255                         ipc.status = IDLE_PROF_STATUS_ABORT;
 256                         log_err("fio: pthread_create %s\n", strerror(ret));
 257                         break;
 258                 } else
 259                         ipt->state = TD_CREATED;
 260
 261                 if ((ret = pthread_detach(ipt->thread))) {
 262                         /* log error and let the thread spin */
 263                         log_err("fio: pthread_detach %s\n", strerror(ret));
 264                 }
 265         }
 266
 267         /*
 268          * let good threads continue so that they can exit
 269          * if errors on other threads occurred previously.
 270          */
 271         for (i = 0; i < ipc.nr_cpus; i++) {
 272                 ipt = &ipc.ipts[i];
 273                 pthread_mutex_unlock(&ipt->init_lock);
 274         }
 275
 276         if (ipc.status == IDLE_PROF_STATUS_ABORT)
 277                 return;
 278
 279         /* wait for calibration to finish */
 280         for (i = 0; i < ipc.nr_cpus; i++) {
 281                 ipt = &ipc.ipts[i];
 282                 pthread_mutex_lock(&ipt->init_lock);
 283                 while ((ipt->state != TD_EXITED) &&
 284                        (ipt->state!=TD_INITIALIZED)) {
 285                         fio_gettime(&tp, NULL);
 286                         ts.tv_sec = tp.tv_sec + 1;
 287                         ts.tv_nsec = tp.tv_usec * 1000;
 288                         pthread_cond_timedwait(&ipt->cond, &ipt->init_lock, &ts);
 289                 }
 290                 pthread_mutex_unlock(&ipt->init_lock);
 291
 292                 /*
 293                  * any thread failed to initialize would abort other threads
 294                  * later after fio_idle_prof_start.
 295                  */
 296                 if (ipt->state == TD_EXITED)
 297                         ipc.status = IDLE_PROF_STATUS_ABORT;
 298         }
 299
 300         if (ipc.status != IDLE_PROF_STATUS_ABORT)
 301                 calibration_stats();
 302         else
 303                 ipc.cali_mean = ipc.cali_stddev = 0.0;
 304
 305         if (ipc.opt == IDLE_PROF_OPT_CALI)
 306                 ipc.status = IDLE_PROF_STATUS_CALI_STOP;
 307 }
 308
 309 void fio_idle_prof_start(void)
 310 {
 311         int i;
 312         struct idle_prof_thread *ipt;
 313
 314         if (ipc.opt == IDLE_PROF_OPT_NONE)
 315                 return;
 316
 317         /* unlock regardless abort is set or not */
 318         for (i = 0; i < ipc.nr_cpus; i++) {
 319                 ipt = &ipc.ipts[i];
 320                 pthread_mutex_unlock(&ipt->start_lock);
 321         }
 322 }
 323
 324 void fio_idle_prof_stop(void)
 325 {
 326         int i;
 327         uint64_t runt;
 328         struct timeval tp;
 329         struct timespec ts;
 330         struct idle_prof_thread *ipt;
 331
 332         if (ipc.opt == IDLE_PROF_OPT_NONE)
 333                 return;
 334
 335         if (ipc.opt == IDLE_PROF_OPT_CALI)
 336                 return;
 337
 338         ipc.status = IDLE_PROF_STATUS_PROF_STOP;
 339
 340         /* wait for all threads to exit from profiling */
 341         for (i = 0; i < ipc.nr_cpus; i++) {
 342                 ipt = &ipc.ipts[i];
 343                 pthread_mutex_lock(&ipt->start_lock);
 344                 while ((ipt->state != TD_EXITED) &&
 345                        (ipt->state!=TD_NOT_CREATED)) {
 346                         fio_gettime(&tp, NULL);
 347                         ts.tv_sec = tp.tv_sec + 1;
 348                         ts.tv_nsec = tp.tv_usec * 1000;
 349                         /* timed wait in case a signal is not received */
 350                         pthread_cond_timedwait(&ipt->cond, &ipt->start_lock, &ts);
 351                 }
 352                 pthread_mutex_unlock(&ipt->start_lock);
 353
 354                 /* calculate idleness */
 355                 if (ipc.cali_mean != 0.0) {
 356                         runt = utime_since(&ipt->tps, &ipt->tpe);
 357                         if (runt)
 358                                 ipt->idleness = ipt->loops * ipc.cali_mean / runt;
 359                         else
 360                                 ipt->idleness = 0.0;
 361                 } else
 362                         ipt->idleness = 0.0;
 363         }
 364
 365         /*
 366          * memory allocations are freed via explicit fio_idle_prof_cleanup
 367          * after profiling stats are collected by apps.
 368          */
 369 }
 370
 371 /*
 372  * return system idle percentage when cpu is -1;
 373  * return one cpu idle percentage otherwise.
 374  */
 375 static double fio_idle_prof_cpu_stat(int cpu)
 376 {
 377         int i, nr_cpus = ipc.nr_cpus;
 378         struct idle_prof_thread *ipt;
 379         double p = 0.0;
 380
 381         if (ipc.opt == IDLE_PROF_OPT_NONE)
 382                 return 0.0;
 383
 384         if ((cpu >= nr_cpus) || (cpu < -1)) {
 385                 log_err("fio: idle profiling invalid cpu index\n");
 386                 return 0.0;
 387         }
 388
 389         if (cpu == -1) {
 390                 for (i = 0; i < nr_cpus; i++) {
 391                         ipt = &ipc.ipts[i];
 392                         p += ipt->idleness;
 393                 }
 394                 p /= nr_cpus;
 395         } else {
 396                 ipt = &ipc.ipts[cpu];
 397                 p = ipt->idleness;
 398         }
 399
 400         return p * 100.0;
 401 }
 402
 403 static void fio_idle_prof_cleanup(void)
 404 {
 405         if (ipc.ipts) {
 406                 free(ipc.ipts);
 407                 ipc.ipts = NULL;
 408         }
 409
 410         if (ipc.buf) {
 411                 free(ipc.buf);
 412                 ipc.buf = NULL;
 413         }
 414 }
 415
 416 int fio_idle_prof_parse_opt(const char *args)
 417 {
 418         ipc.opt = IDLE_PROF_OPT_NONE; /* default */
 419
 420         if (!args) {
 421                 log_err("fio: empty idle-prof option string\n");
 422                 return -1;
 423         }
 424
 425 #if defined(FIO_HAVE_CPU_AFFINITY) && defined(CONFIG_SCHED_IDLE)
 426         if (strcmp("calibrate", args) == 0) {
 427                 ipc.opt = IDLE_PROF_OPT_CALI;
 428                 fio_idle_prof_init();
 429                 fio_idle_prof_start();
 430                 fio_idle_prof_stop();
 431                 show_idle_prof_stats(FIO_OUTPUT_NORMAL, NULL, NULL);
 432                 return 1;
 433         } else if (strcmp("system", args) == 0) {
 434                 ipc.opt = IDLE_PROF_OPT_SYSTEM;
 435                 return 0;
 436         } else if (strcmp("percpu", args) == 0) {
 437                 ipc.opt = IDLE_PROF_OPT_PERCPU;
 438                 return 0;
 439         } else {
 440                 log_err("fio: incorrect idle-prof option: %s\n", args);
 441                 return -1;
 442         }
 443 #else
 444         log_err("fio: idle-prof not supported on this platform\n");
 445         return -1;
 446 #endif
 447 }
 448
 449 void show_idle_prof_stats(int output, struct json_object *parent,
 450                           struct buf_output *out)
 451 {
 452         int i, nr_cpus = ipc.nr_cpus;
 453         struct json_object *tmp;
 454         char s[MAX_CPU_STR_LEN];
 455
 456         if (output == FIO_OUTPUT_NORMAL) {
 457                 if (ipc.opt > IDLE_PROF_OPT_CALI)
 458                         log_buf(out, "\nCPU idleness:\n");
 459                 else if (ipc.opt == IDLE_PROF_OPT_CALI)
 460                         log_buf(out, "CPU idleness:\n");
 461
 462                 if (ipc.opt >= IDLE_PROF_OPT_SYSTEM)
 463                         log_buf(out, "  system: %3.2f%%\n", fio_idle_prof_cpu_stat(-1));
 464
 465                 if (ipc.opt == IDLE_PROF_OPT_PERCPU) {
 466                         log_buf(out, "  percpu: %3.2f%%", fio_idle_prof_cpu_stat(0));
 467                         for (i = 1; i < nr_cpus; i++)
 468                                 log_buf(out, ", %3.2f%%", fio_idle_prof_cpu_stat(i));
 469                         log_buf(out, "\n");
 470                 }
 471
 472                 if (ipc.opt >= IDLE_PROF_OPT_CALI) {
 473                         log_buf(out, "  unit work: mean=%3.2fus,", ipc.cali_mean);
 474                         log_buf(out, " stddev=%3.2f\n", ipc.cali_stddev);
 475                 }
 476
 477                 /* dynamic mem allocations can now be freed */
 478                 if (ipc.opt != IDLE_PROF_OPT_NONE)
 479                         fio_idle_prof_cleanup();
 480
 481                 return;
 482         }
 483
 484         if ((ipc.opt != IDLE_PROF_OPT_NONE) && (output & FIO_OUTPUT_JSON)) {
 485                 if (!parent)
 486                         return;
 487
 488                 tmp = json_create_object();
 489                 if (!tmp)
 490                         return;
 491
 492                 json_object_add_value_object(parent, "cpu_idleness", tmp);
 493                 json_object_add_value_float(tmp, "system", fio_idle_prof_cpu_stat(-1));
 494
 495                 if (ipc.opt == IDLE_PROF_OPT_PERCPU) {
 496                         for (i = 0; i < nr_cpus; i++) {
 497                                 snprintf(s, MAX_CPU_STR_LEN, "cpu-%d", i);
 498                                 json_object_add_value_float(tmp, s, fio_idle_prof_cpu_stat(i));
 499                         }
 500                 }
 501
 502                 json_object_add_value_float(tmp, "unit_mean", ipc.cali_mean);
 503                 json_object_add_value_float(tmp, "unit_stddev", ipc.cali_stddev);
 504
 505                 fio_idle_prof_cleanup();
 506         }
 507 }