workqueue.c

   1 /*
   2  * Generic workqueue offload mechanism
   3  *
   4  * Copyright (C) 2015 Jens Axboe <axboe@kernel.dk>
   5  *
   6  */
   7 #include <unistd.h>
   8
   9 #include "fio.h"
  10 #include "flist.h"
  11 #include "workqueue.h"
  12 #include "smalloc.h"
  13 #include "pshared.h"
  14
  15 enum {
  16         SW_F_IDLE       = 1 << 0,
  17         SW_F_RUNNING    = 1 << 1,
  18         SW_F_EXIT       = 1 << 2,
  19         SW_F_ACCOUNTED  = 1 << 3,
  20         SW_F_ERROR      = 1 << 4,
  21 };
  22
  23 static struct submit_worker *__get_submit_worker(struct workqueue *wq,
  24                                                  unsigned int start,
  25                                                  unsigned int end,
  26                                                  struct submit_worker **best)
  27 {
  28         struct submit_worker *sw = NULL;
  29
  30         while (start <= end) {
  31                 sw = &wq->workers[start];
  32                 if (sw->flags & SW_F_IDLE)
  33                         return sw;
  34                 if (!(*best) || sw->seq < (*best)->seq)
  35                         *best = sw;
  36                 start++;
  37         }
  38
  39         return NULL;
  40 }
  41
  42 static struct submit_worker *get_submit_worker(struct workqueue *wq)
  43 {
  44         unsigned int next = wq->next_free_worker;
  45         struct submit_worker *sw, *best = NULL;
  46
  47         assert(next < wq->max_workers);
  48
  49         sw = __get_submit_worker(wq, next, wq->max_workers - 1, &best);
  50         if (!sw && next)
  51                 sw = __get_submit_worker(wq, 0, next - 1, &best);
  52
  53         /*
  54          * No truly idle found, use best match
  55          */
  56         if (!sw)
  57                 sw = best;
  58
  59         if (sw->index == wq->next_free_worker) {
  60                 if (sw->index + 1 < wq->max_workers)
  61                         wq->next_free_worker = sw->index + 1;
  62                 else
  63                         wq->next_free_worker = 0;
  64         }
  65
  66         return sw;
  67 }
  68
  69 static bool all_sw_idle(struct workqueue *wq)
  70 {
  71         int i;
  72
  73         for (i = 0; i < wq->max_workers; i++) {
  74                 struct submit_worker *sw = &wq->workers[i];
  75
  76                 if (!(sw->flags & SW_F_IDLE))
  77                         return false;
  78         }
  79
  80         return true;
  81 }
  82
  83 /*
  84  * Must be serialized wrt workqueue_enqueue() by caller
  85  */
  86 void workqueue_flush(struct workqueue *wq)
  87 {
  88         pthread_mutex_lock(&wq->flush_lock);
  89         wq->wake_idle = 1;
  90
  91         while (!all_sw_idle(wq))
  92                 pthread_cond_wait(&wq->flush_cond, &wq->flush_lock);
  93
  94         wq->wake_idle = 0;
  95         pthread_mutex_unlock(&wq->flush_lock);
  96 }
  97
  98 /*
  99  * Must be serialized by caller.
 100  */
 101 void workqueue_enqueue(struct workqueue *wq, struct workqueue_work *work)
 102 {
 103         struct submit_worker *sw;
 104
 105         sw = get_submit_worker(wq);
 106         assert(sw);
 107
 108         pthread_mutex_lock(&sw->lock);
 109         flist_add_tail(&work->list, &sw->work_list);
 110         sw->seq = ++wq->work_seq;
 111         sw->flags &= ~SW_F_IDLE;
 112
 113         pthread_cond_signal(&sw->cond);
 114         pthread_mutex_unlock(&sw->lock);
 115 }
 116
 117 static void handle_list(struct submit_worker *sw, struct flist_head *list)
 118 {
 119         struct workqueue *wq = sw->wq;
 120         struct workqueue_work *work;
 121
 122         while (!flist_empty(list)) {
 123                 work = flist_first_entry(list, struct workqueue_work, list);
 124                 flist_del_init(&work->list);
 125                 wq->ops.fn(sw, work);
 126         }
 127 }
 128
 129 static void *worker_thread(void *data)
 130 {
 131         struct submit_worker *sw = data;
 132         struct workqueue *wq = sw->wq;
 133         unsigned int ret = 0;
 134         FLIST_HEAD(local_list);
 135
 136         sk_out_assign(sw->sk_out);
 137
 138         if (wq->ops.nice) {
 139                 errno = 0;
 140                 if (nice(wq->ops.nice) == -1 && errno != 0) {
 141                         log_err("workqueue: nice %s\n", strerror(errno));
 142                         ret = 1;
 143                 }
 144         }
 145
 146         if (!ret)
 147                 ret = workqueue_init_worker(sw);
 148
 149         pthread_mutex_lock(&sw->lock);
 150         sw->flags |= SW_F_RUNNING;
 151         if (ret)
 152                 sw->flags |= SW_F_ERROR;
 153         pthread_mutex_unlock(&sw->lock);
 154
 155         pthread_mutex_lock(&wq->flush_lock);
 156         pthread_cond_signal(&wq->flush_cond);
 157         pthread_mutex_unlock(&wq->flush_lock);
 158
 159         if (sw->flags & SW_F_ERROR)
 160                 goto done;
 161
 162         pthread_mutex_lock(&sw->lock);
 163         while (1) {
 164                 if (flist_empty(&sw->work_list)) {
 165                         if (sw->flags & SW_F_EXIT) {
 166                                 break;
 167                         }
 168
 169                         if (workqueue_pre_sleep_check(sw)) {
 170                                 pthread_mutex_unlock(&sw->lock);
 171                                 workqueue_pre_sleep(sw);
 172                                 pthread_mutex_lock(&sw->lock);
 173                         }
 174                 }
 175                 /*
 176                  * We may have dropped and reaquired the lock, check state
 177                  * again.
 178                  */
 179                 if (flist_empty(&sw->work_list)) {
 180                         if (sw->flags & SW_F_EXIT) {
 181                                 break;
 182                         }
 183                         if (!(sw->flags & SW_F_IDLE)) {
 184                                 sw->flags |= SW_F_IDLE;
 185                                 wq->next_free_worker = sw->index;
 186                                 pthread_mutex_unlock(&sw->lock);
 187                                 pthread_mutex_lock(&wq->flush_lock);
 188                                 if (wq->wake_idle)
 189                                         pthread_cond_signal(&wq->flush_cond);
 190                                 pthread_mutex_unlock(&wq->flush_lock);
 191                                 pthread_mutex_lock(&sw->lock);
 192                         }
 193                 }
 194                 if (flist_empty(&sw->work_list)) {
 195                         if (sw->flags & SW_F_EXIT) {
 196                                 break;
 197                         }
 198                         pthread_cond_wait(&sw->cond, &sw->lock);
 199                 } else {
 200                         flist_splice_init(&sw->work_list, &local_list);
 201                 }
 202                 pthread_mutex_unlock(&sw->lock);
 203                 handle_list(sw, &local_list);
 204                 if (wq->ops.update_acct_fn)
 205                         wq->ops.update_acct_fn(sw);
 206                 pthread_mutex_lock(&sw->lock);
 207         }
 208         pthread_mutex_unlock(&sw->lock);
 209
 210 done:
 211         sk_out_drop();
 212         return NULL;
 213 }
 214
 215 static void free_worker(struct submit_worker *sw, unsigned int *sum_cnt)
 216 {
 217         struct workqueue *wq = sw->wq;
 218
 219         workqueue_exit_worker(sw, sum_cnt);
 220
 221         pthread_cond_destroy(&sw->cond);
 222         pthread_mutex_destroy(&sw->lock);
 223
 224         if (wq->ops.free_worker_fn)
 225                 wq->ops.free_worker_fn(sw);
 226 }
 227
 228 static void shutdown_worker(struct submit_worker *sw, unsigned int *sum_cnt)
 229 {
 230         pthread_join(sw->thread, NULL);
 231         free_worker(sw, sum_cnt);
 232 }
 233
 234 void workqueue_exit(struct workqueue *wq)
 235 {
 236         unsigned int shutdown, sum_cnt = 0;
 237         struct submit_worker *sw;
 238         int i;
 239
 240         if (!wq->workers)
 241                 return;
 242
 243         for (i = 0; i < wq->max_workers; i++) {
 244                 sw = &wq->workers[i];
 245
 246                 pthread_mutex_lock(&sw->lock);
 247                 sw->flags |= SW_F_EXIT;
 248                 pthread_cond_signal(&sw->cond);
 249                 pthread_mutex_unlock(&sw->lock);
 250         }
 251
 252         do {
 253                 shutdown = 0;
 254                 for (i = 0; i < wq->max_workers; i++) {
 255                         sw = &wq->workers[i];
 256                         if (sw->flags & SW_F_ACCOUNTED)
 257                                 continue;
 258                         pthread_mutex_lock(&sw->lock);
 259                         sw->flags |= SW_F_ACCOUNTED;
 260                         pthread_mutex_unlock(&sw->lock);
 261                         shutdown_worker(sw, &sum_cnt);
 262                         shutdown++;
 263                 }
 264         } while (shutdown && shutdown != wq->max_workers);
 265
 266         sfree(wq->workers);
 267         wq->workers = NULL;
 268         pthread_mutex_destroy(&wq->flush_lock);
 269         pthread_cond_destroy(&wq->flush_cond);
 270         pthread_mutex_destroy(&wq->stat_lock);
 271 }
 272
 273 static int start_worker(struct workqueue *wq, unsigned int index,
 274                         struct sk_out *sk_out)
 275 {
 276         struct submit_worker *sw = &wq->workers[index];
 277         int ret;
 278
 279         INIT_FLIST_HEAD(&sw->work_list);
 280
 281         ret = mutex_cond_init_pshared(&sw->lock, &sw->cond);
 282         if (ret)
 283                 return ret;
 284
 285         sw->wq = wq;
 286         sw->index = index;
 287         sw->sk_out = sk_out;
 288
 289         if (wq->ops.alloc_worker_fn) {
 290                 ret = wq->ops.alloc_worker_fn(sw);
 291                 if (ret)
 292                         return ret;
 293         }
 294
 295         ret = pthread_create(&sw->thread, NULL, worker_thread, sw);
 296         if (!ret) {
 297                 pthread_mutex_lock(&sw->lock);
 298                 sw->flags = SW_F_IDLE;
 299                 pthread_mutex_unlock(&sw->lock);
 300                 return 0;
 301         }
 302
 303         free_worker(sw, NULL);
 304         return 1;
 305 }
 306
 307 int workqueue_init(struct thread_data *td, struct workqueue *wq,
 308                    struct workqueue_ops *ops, unsigned int max_workers,
 309                    struct sk_out *sk_out)
 310 {
 311         unsigned int running;
 312         int i, error;
 313         int ret;
 314
 315         wq->max_workers = max_workers;
 316         wq->td = td;
 317         wq->ops = *ops;
 318         wq->work_seq = 0;
 319         wq->next_free_worker = 0;
 320
 321         ret = mutex_cond_init_pshared(&wq->flush_lock, &wq->flush_cond);
 322         if (ret)
 323                 goto err;
 324         ret = mutex_init_pshared(&wq->stat_lock);
 325         if (ret)
 326                 goto err;
 327
 328         wq->workers = smalloc(wq->max_workers * sizeof(struct submit_worker));
 329         if (!wq->workers)
 330                 goto err;
 331
 332         for (i = 0; i < wq->max_workers; i++)
 333                 if (start_worker(wq, i, sk_out))
 334                         break;
 335
 336         wq->max_workers = i;
 337         if (!wq->max_workers)
 338                 goto err;
 339
 340         /*
 341          * Wait for them all to be started and initialized
 342          */
 343         error = 0;
 344         pthread_mutex_lock(&wq->flush_lock);
 345         do {
 346                 struct submit_worker *sw;
 347
 348                 running = 0;
 349                 for (i = 0; i < wq->max_workers; i++) {
 350                         sw = &wq->workers[i];
 351                         pthread_mutex_lock(&sw->lock);
 352                         if (sw->flags & SW_F_RUNNING)
 353                                 running++;
 354                         if (sw->flags & SW_F_ERROR)
 355                                 error++;
 356                         pthread_mutex_unlock(&sw->lock);
 357                 }
 358
 359                 if (error || running == wq->max_workers)
 360                         break;
 361
 362                 pthread_cond_wait(&wq->flush_cond, &wq->flush_lock);
 363         } while (1);
 364         pthread_mutex_unlock(&wq->flush_lock);
 365
 366         if (!error)
 367                 return 0;
 368
 369 err:
 370         log_err("Can't create rate workqueue\n");
 371         td_verror(td, ESRCH, "workqueue_init");
 372         workqueue_exit(wq);
 373         return 1;
 374 }