src/util/u_queue.c

   1 /*
   2  * Copyright © 2016 Advanced Micro Devices, Inc.
   3  * All Rights Reserved.
   4  *
   5  * Permission is hereby granted, free of charge, to any person obtaining
   6  * a copy of this software and associated documentation files (the
   7  * "Software"), to deal in the Software without restriction, including
   8  * without limitation the rights to use, copy, modify, merge, publish,
   9  * distribute, sub license, and/or sell copies of the Software, and to
  10  * permit persons to whom the Software is furnished to do so, subject to
  11  * the following conditions:
  12  *
  13  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  14  * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
  15  * OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  16  * NON-INFRINGEMENT. IN NO EVENT SHALL THE COPYRIGHT HOLDERS, AUTHORS
  17  * AND/OR ITS SUPPLIERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  18  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
  19  * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
  20  * USE OR OTHER DEALINGS IN THE SOFTWARE.
  21  *
  22  * The above copyright notice and this permission notice (including the
  23  * next paragraph) shall be included in all copies or substantial portions
  24  * of the Software.
  25  */
  26
  27 #include "u_queue.h"
  28 #include "util/u_string.h"
  29
  30 static void util_queue_killall_and_wait(struct util_queue *queue);
  31
  32 /****************************************************************************
  33  * Wait for all queues to assert idle when exit() is called.
  34  *
  35  * Otherwise, C++ static variable destructors can be called while threads
  36  * are using the static variables.
  37  */
  38
  39 static once_flag atexit_once_flag = ONCE_FLAG_INIT;
  40 static struct list_head queue_list;
  41 static mtx_t exit_mutex = _MTX_INITIALIZER_NP;
  42
  43 static void
  44 atexit_handler(void)
  45 {
  46    struct util_queue *iter;
  47
  48    mtx_lock(&exit_mutex);
  49    /* Wait for all queues to assert idle. */
  50    LIST_FOR_EACH_ENTRY(iter, &queue_list, head) {
  51       util_queue_killall_and_wait(iter);
  52    }
  53    mtx_unlock(&exit_mutex);
  54 }
  55
  56 static void
  57 global_init(void)
  58 {
  59    LIST_INITHEAD(&queue_list);
  60    atexit(atexit_handler);
  61 }
  62
  63 static void
  64 add_to_atexit_list(struct util_queue *queue)
  65 {
  66    call_once(&atexit_once_flag, global_init);
  67
  68    mtx_lock(&exit_mutex);
  69    LIST_ADD(&queue->head, &queue_list);
  70    mtx_unlock(&exit_mutex);
  71 }
  72
  73 static void
  74 remove_from_atexit_list(struct util_queue *queue)
  75 {
  76    struct util_queue *iter, *tmp;
  77
  78    mtx_lock(&exit_mutex);
  79    LIST_FOR_EACH_ENTRY_SAFE(iter, tmp, &queue_list, head) {
  80       if (iter == queue) {
  81          LIST_DEL(&iter->head);
  82          break;
  83       }
  84    }
  85    mtx_unlock(&exit_mutex);
  86 }
  87
  88 /****************************************************************************
  89  * util_queue_fence
  90  */
  91
  92 static void
  93 util_queue_fence_signal(struct util_queue_fence *fence)
  94 {
  95    mtx_lock(&fence->mutex);
  96    fence->signalled = true;
  97    cnd_broadcast(&fence->cond);
  98    mtx_unlock(&fence->mutex);
  99 }
 100
 101 void
 102 util_queue_fence_wait(struct util_queue_fence *fence)
 103 {
 104    mtx_lock(&fence->mutex);
 105    while (!fence->signalled)
 106       cnd_wait(&fence->cond, &fence->mutex);
 107    mtx_unlock(&fence->mutex);
 108 }
 109
 110 void
 111 util_queue_fence_init(struct util_queue_fence *fence)
 112 {
 113    memset(fence, 0, sizeof(*fence));
 114    (void) mtx_init(&fence->mutex, mtx_plain);
 115    cnd_init(&fence->cond);
 116    fence->signalled = true;
 117 }
 118
 119 void
 120 util_queue_fence_destroy(struct util_queue_fence *fence)
 121 {
 122    assert(fence->signalled);
 123
 124    /* Ensure that another thread is not in the middle of
 125     * util_queue_fence_signal (having set the fence to signalled but still
 126     * holding the fence mutex).
 127     *
 128     * A common contract between threads is that as soon as a fence is signalled
 129     * by thread A, thread B is allowed to destroy it. Since
 130     * util_queue_fence_is_signalled does not lock the fence mutex (for
 131     * performance reasons), we must do so here.
 132     */
 133    mtx_lock(&fence->mutex);
 134    mtx_unlock(&fence->mutex);
 135
 136    cnd_destroy(&fence->cond);
 137    mtx_destroy(&fence->mutex);
 138 }
 139
 140 /****************************************************************************
 141  * util_queue implementation
 142  */
 143
 144 struct thread_input {
 145    struct util_queue *queue;
 146    int thread_index;
 147 };
 148
 149 static int
 150 util_queue_thread_func(void *input)
 151 {
 152    struct util_queue *queue = ((struct thread_input*)input)->queue;
 153    int thread_index = ((struct thread_input*)input)->thread_index;
 154
 155    free(input);
 156
 157    if (queue->name) {
 158       char name[16];
 159       util_snprintf(name, sizeof(name), "%s:%i", queue->name, thread_index);
 160       u_thread_setname(name);
 161    }
 162
 163    while (1) {
 164       struct util_queue_job job;
 165
 166       mtx_lock(&queue->lock);
 167       assert(queue->num_queued >= 0 && queue->num_queued <= queue->max_jobs);
 168
 169       /* wait if the queue is empty */
 170       while (!queue->kill_threads && queue->num_queued == 0)
 171          cnd_wait(&queue->has_queued_cond, &queue->lock);
 172
 173       if (queue->kill_threads) {
 174          mtx_unlock(&queue->lock);
 175          break;
 176       }
 177
 178       job = queue->jobs[queue->read_idx];
 179       memset(&queue->jobs[queue->read_idx], 0, sizeof(struct util_queue_job));
 180       queue->read_idx = (queue->read_idx + 1) % queue->max_jobs;
 181
 182       queue->num_queued--;
 183       cnd_signal(&queue->has_space_cond);
 184       mtx_unlock(&queue->lock);
 185
 186       if (job.job) {
 187          job.execute(job.job, thread_index);
 188          util_queue_fence_signal(job.fence);
 189          if (job.cleanup)
 190             job.cleanup(job.job, thread_index);
 191       }
 192    }
 193
 194    /* signal remaining jobs before terminating */
 195    mtx_lock(&queue->lock);
 196    for (unsigned i = queue->read_idx; i != queue->write_idx;
 197         i = (i + 1) % queue->max_jobs) {
 198       if (queue->jobs[i].job) {
 199          util_queue_fence_signal(queue->jobs[i].fence);
 200          queue->jobs[i].job = NULL;
 201       }
 202    }
 203    queue->read_idx = queue->write_idx;
 204    queue->num_queued = 0;
 205    mtx_unlock(&queue->lock);
 206    return 0;
 207 }
 208
 209 bool
 210 util_queue_init(struct util_queue *queue,
 211                 const char *name,
 212                 unsigned max_jobs,
 213                 unsigned num_threads,
 214                 unsigned flags)
 215 {
 216    unsigned i;
 217
 218    memset(queue, 0, sizeof(*queue));
 219    queue->name = name;
 220    queue->flags = flags;
 221    queue->num_threads = num_threads;
 222    queue->max_jobs = max_jobs;
 223
 224    queue->jobs = (struct util_queue_job*)
 225                  calloc(max_jobs, sizeof(struct util_queue_job));
 226    if (!queue->jobs)
 227       goto fail;
 228
 229    (void) mtx_init(&queue->lock, mtx_plain);
 230
 231    queue->num_queued = 0;
 232    cnd_init(&queue->has_queued_cond);
 233    cnd_init(&queue->has_space_cond);
 234
 235    queue->threads = (thrd_t*) calloc(num_threads, sizeof(thrd_t));
 236    if (!queue->threads)
 237       goto fail;
 238
 239    /* start threads */
 240    for (i = 0; i < num_threads; i++) {
 241       struct thread_input *input =
 242          (struct thread_input *) malloc(sizeof(struct thread_input));
 243       input->queue = queue;
 244       input->thread_index = i;
 245
 246       queue->threads[i] = u_thread_create(util_queue_thread_func, input);
 247
 248       if (!queue->threads[i]) {
 249          free(input);
 250
 251          if (i == 0) {
 252             /* no threads created, fail */
 253             goto fail;
 254          } else {
 255             /* at least one thread created, so use it */
 256             queue->num_threads = i;
 257             break;
 258          }
 259       }
 260
 261       if (flags & UTIL_QUEUE_INIT_USE_MINIMUM_PRIORITY) {
 262    #if defined(__linux__) && defined(SCHED_IDLE)
 263          struct sched_param sched_param = {0};
 264
 265          /* The nice() function can only set a maximum of 19.
 266           * SCHED_IDLE is the same as nice = 20.
 267           *
 268           * Note that Linux only allows decreasing the priority. The original
 269           * priority can't be restored.
 270           */
 271          pthread_setschedparam(queue->threads[i], SCHED_IDLE, &sched_param);
 272    #endif
 273       }
 274    }
 275
 276    add_to_atexit_list(queue);
 277    return true;
 278
 279 fail:
 280    free(queue->threads);
 281
 282    if (queue->jobs) {
 283       cnd_destroy(&queue->has_space_cond);
 284       cnd_destroy(&queue->has_queued_cond);
 285       mtx_destroy(&queue->lock);
 286       free(queue->jobs);
 287    }
 288    /* also util_queue_is_initialized can be used to check for success */
 289    memset(queue, 0, sizeof(*queue));
 290    return false;
 291 }
 292
 293 static void
 294 util_queue_killall_and_wait(struct util_queue *queue)
 295 {
 296    unsigned i;
 297
 298    /* Signal all threads to terminate. */
 299    mtx_lock(&queue->lock);
 300    queue->kill_threads = 1;
 301    cnd_broadcast(&queue->has_queued_cond);
 302    mtx_unlock(&queue->lock);
 303
 304    for (i = 0; i < queue->num_threads; i++)
 305       thrd_join(queue->threads[i], NULL);
 306    queue->num_threads = 0;
 307 }
 308
 309 void
 310 util_queue_destroy(struct util_queue *queue)
 311 {
 312    util_queue_killall_and_wait(queue);
 313    remove_from_atexit_list(queue);
 314
 315    cnd_destroy(&queue->has_space_cond);
 316    cnd_destroy(&queue->has_queued_cond);
 317    mtx_destroy(&queue->lock);
 318    free(queue->jobs);
 319    free(queue->threads);
 320 }
 321
 322 void
 323 util_queue_add_job(struct util_queue *queue,
 324                    void *job,
 325                    struct util_queue_fence *fence,
 326                    util_queue_execute_func execute,
 327                    util_queue_execute_func cleanup)
 328 {
 329    struct util_queue_job *ptr;
 330
 331    assert(fence->signalled);
 332
 333    mtx_lock(&queue->lock);
 334    if (queue->kill_threads) {
 335       mtx_unlock(&queue->lock);
 336       /* well no good option here, but any leaks will be
 337        * short-lived as things are shutting down..
 338        */
 339       return;
 340    }
 341
 342    fence->signalled = false;
 343
 344    assert(queue->num_queued >= 0 && queue->num_queued <= queue->max_jobs);
 345
 346    if (queue->num_queued == queue->max_jobs) {
 347       if (queue->flags & UTIL_QUEUE_INIT_RESIZE_IF_FULL) {
 348          /* If the queue is full, make it larger to avoid waiting for a free
 349           * slot.
 350           */
 351          unsigned new_max_jobs = queue->max_jobs + 8;
 352          struct util_queue_job *jobs =
 353             (struct util_queue_job*)calloc(new_max_jobs,
 354                                            sizeof(struct util_queue_job));
 355          assert(jobs);
 356
 357          /* Copy all queued jobs into the new list. */
 358          unsigned num_jobs = 0;
 359          unsigned i = queue->read_idx;
 360
 361          do {
 362             jobs[num_jobs++] = queue->jobs[i];
 363             i = (i + 1) % queue->max_jobs;
 364          } while (i != queue->write_idx);
 365
 366          assert(num_jobs == queue->num_queued);
 367
 368          free(queue->jobs);
 369          queue->jobs = jobs;
 370          queue->read_idx = 0;
 371          queue->write_idx = num_jobs;
 372          queue->max_jobs = new_max_jobs;
 373       } else {
 374          /* Wait until there is a free slot. */
 375          while (queue->num_queued == queue->max_jobs)
 376             cnd_wait(&queue->has_space_cond, &queue->lock);
 377       }
 378    }
 379
 380    ptr = &queue->jobs[queue->write_idx];
 381    assert(ptr->job == NULL);
 382    ptr->job = job;
 383    ptr->fence = fence;
 384    ptr->execute = execute;
 385    ptr->cleanup = cleanup;
 386    queue->write_idx = (queue->write_idx + 1) % queue->max_jobs;
 387
 388    queue->num_queued++;
 389    cnd_signal(&queue->has_queued_cond);
 390    mtx_unlock(&queue->lock);
 391 }
 392
 393 /**
 394  * Remove a queued job. If the job hasn't started execution, it's removed from
 395  * the queue. If the job has started execution, the function waits for it to
 396  * complete.
 397  *
 398  * In all cases, the fence is signalled when the function returns.
 399  *
 400  * The function can be used when destroying an object associated with the job
 401  * when you don't care about the job completion state.
 402  */
 403 void
 404 util_queue_drop_job(struct util_queue *queue, struct util_queue_fence *fence)
 405 {
 406    bool removed = false;
 407
 408    if (util_queue_fence_is_signalled(fence))
 409       return;
 410
 411    mtx_lock(&queue->lock);
 412    for (unsigned i = queue->read_idx; i != queue->write_idx;
 413         i = (i + 1) % queue->max_jobs) {
 414       if (queue->jobs[i].fence == fence) {
 415          if (queue->jobs[i].cleanup)
 416             queue->jobs[i].cleanup(queue->jobs[i].job, -1);
 417
 418          /* Just clear it. The threads will treat as a no-op job. */
 419          memset(&queue->jobs[i], 0, sizeof(queue->jobs[i]));
 420          removed = true;
 421          break;
 422       }
 423    }
 424    mtx_unlock(&queue->lock);
 425
 426    if (removed)
 427       util_queue_fence_signal(fence);
 428    else
 429       util_queue_fence_wait(fence);
 430 }
 431
 432 int64_t
 433 util_queue_get_thread_time_nano(struct util_queue *queue, unsigned thread_index)
 434 {
 435    /* Allow some flexibility by not raising an error. */
 436    if (thread_index >= queue->num_threads)
 437       return 0;
 438
 439    return u_thread_get_time_nano(queue->threads[thread_index]);
 440 }