kernel/pwqr.c

   1 /*
   2  * Copyright (C) 2012   Pierre Habouzit <pierre.habouzit@intersec.com>
   3  * Copyright (C) 2012   Intersec SAS
   4  *
   5  * This file implements the Linux Pthread Workqueue Regulator, and is part
   6  * of the linux kernel.
   7  *
   8  * The Linux Kernel is free software: you can redistribute it and/or modify it
   9  * under the terms of the GNU General Public License version 2 as published by
  10  * the Free Software Foundation.
  11  *
  12  * The Linux Kernel is distributed in the hope that it will be useful, but
  13  * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
  14  * or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public
  15  * License for more details.
  16  *
  17  * You should have received a copy of the GNU General Public License version 2
  18  * along with The Linux Kernel.  If not, see <http://www.gnu.org/licenses/>.
  19  */
  20
  21 #include <linux/cdev.h>
  22 #include <linux/device.h>
  23 #include <linux/file.h>
  24 #include <linux/fs.h>
  25 #include <linux/hash.h>
  26 #include <linux/init.h>
  27 #include <linux/kref.h>
  28 #include <linux/module.h>
  29 #include <linux/sched.h>
  30 #include <linux/slab.h>
  31 #include <linux/spinlock.h>
  32 #include <linux/timer.h>
  33 #include <linux/uaccess.h>
  34 #include <linux/wait.h>
  35
  36 #ifndef CONFIG_PREEMPT_NOTIFIERS
  37 #  error PWQ module requires CONFIG_PREEMPT_NOTIFIERS
  38 #endif
  39
  40 #include "pwqr.h"
  41
  42 #define PWQR_UNPARK_DELAY       (HZ / 10)
  43 #define PWQR_HASH_BITS          5
  44 #define PWQR_HASH_SIZE          (1 << PWQR_HASH_BITS)
  45
  46 struct pwqr_task_bucket {
  47         spinlock_t              lock;
  48         struct hlist_head       tasks;
  49 };
  50
  51 struct pwqr_sb {
  52         struct kref             kref;
  53         struct rcu_head         rcu;
  54         struct timer_list       timer;
  55         wait_queue_head_t       wqh;
  56         pid_t                   tgid;
  57
  58         unsigned                concurrency;
  59         unsigned                registered;
  60
  61         unsigned                running;
  62         unsigned                waiting;
  63         unsigned                parked;
  64         unsigned                overcommit_wakes;
  65
  66         unsigned                dead;
  67 };
  68
  69 struct pwqr_task {
  70         struct preempt_notifier notifier;
  71         struct hlist_node       link;
  72         struct rcu_head         rcu;
  73         struct task_struct     *task;
  74         struct pwqr_sb         *sb;
  75 };
  76
  77 /*
  78  * Global variables
  79  */
  80 static struct class            *pwqr_class;
  81 static int                      pwqr_major;
  82 static struct pwqr_task_bucket  pwqr_tasks_hash[PWQR_HASH_SIZE];
  83 static struct preempt_ops       pwqr_preempt_running_ops;
  84 static struct preempt_ops       pwqr_preempt_blocked_ops;
  85 static struct preempt_ops       pwqr_preempt_noop_ops;
  86
  87 /*****************************************************************************
  88  * Scoreboards
  89  */
  90
  91 #define pwqr_sb_lock_irqsave(sb, flags) \
  92         spin_lock_irqsave(&(sb)->wqh.lock, flags)
  93 #define pwqr_sb_unlock_irqrestore(sb, flags) \
  94         spin_unlock_irqrestore(&(sb)->wqh.lock, flags)
  95
  96 static inline void __pwqr_sb_update_state(struct pwqr_sb *sb, int running_delta)
  97 {
  98         sb->running += running_delta;
  99         if (sb->running > sb->concurrency) {
 100                 /* TODO see ../Documentation/pwqr.adoc */
 101         } else if (sb->running == sb->concurrency) {
 102                 /* do nothing */
 103         } else if (sb->waiting == 0 && sb->parked) {
 104                 if (!timer_pending(&sb->timer)) {
 105                         mod_timer(&sb->timer, jiffies + PWQR_UNPARK_DELAY);
 106                 }
 107                 return;
 108         }
 109
 110         if (timer_pending(&sb->timer))
 111                 del_timer(&sb->timer);
 112 }
 113
 114 static void pwqr_sb_timer_cb(unsigned long arg)
 115 {
 116         struct pwqr_sb *sb = (struct pwqr_sb *)arg;
 117         unsigned long flags;
 118
 119         pwqr_sb_lock_irqsave(sb, flags);
 120         if (sb->waiting == 0 && sb->parked && sb->running < sb->concurrency) {
 121                 if (sb->overcommit_wakes == 0)
 122                         wake_up_locked(&sb->wqh);
 123         }
 124         pwqr_sb_unlock_irqrestore(sb, flags);
 125 }
 126
 127 static struct pwqr_sb *pwqr_sb_create(void)
 128 {
 129         struct pwqr_sb *sb;
 130
 131         sb = kzalloc(sizeof(struct pwqr_sb), GFP_KERNEL);
 132         if (sb == NULL)
 133                 return ERR_PTR(-ENOMEM);
 134
 135         kref_init(&sb->kref);
 136         init_waitqueue_head(&sb->wqh);
 137         sb->tgid        = current->tgid;
 138         sb->concurrency = num_online_cpus();
 139         init_timer(&sb->timer);
 140         sb->timer.function = pwqr_sb_timer_cb;
 141         sb->timer.data     = (unsigned long)sb;
 142
 143         __module_get(THIS_MODULE);
 144         return sb;
 145 }
 146 static inline void pwqr_sb_get(struct pwqr_sb *sb)
 147 {
 148         kref_get(&sb->kref);
 149 }
 150
 151 static void pwqr_sb_finalize(struct rcu_head *rcu)
 152 {
 153         struct pwqr_sb *sb = container_of(rcu, struct pwqr_sb, rcu);
 154
 155         module_put(THIS_MODULE);
 156         kfree(sb);
 157 }
 158
 159 static void pwqr_sb_release(struct kref *kref)
 160 {
 161         struct pwqr_sb *sb = container_of(kref, struct pwqr_sb, kref);
 162
 163         del_timer_sync(&sb->timer);
 164         call_rcu(&sb->rcu, pwqr_sb_finalize);
 165 }
 166 static inline void pwqr_sb_put(struct pwqr_sb *sb)
 167 {
 168         kref_put(&sb->kref, pwqr_sb_release);
 169 }
 170
 171 /*****************************************************************************
 172  * tasks
 173  */
 174 static inline struct pwqr_task_bucket *task_hbucket(struct task_struct *task)
 175 {
 176         return &pwqr_tasks_hash[hash_ptr(task, PWQR_HASH_BITS)];
 177 }
 178
 179 static struct pwqr_task *pwqr_task_find(struct task_struct *task)
 180 {
 181         struct pwqr_task_bucket *b = task_hbucket(task);
 182         struct hlist_node *node;
 183         struct pwqr_task *pwqt = NULL;
 184
 185         spin_lock(&b->lock);
 186         hlist_for_each_entry(pwqt, node, &b->tasks, link) {
 187                 if (pwqt->task == task)
 188                         break;
 189         }
 190         spin_unlock(&b->lock);
 191         return pwqt;
 192 }
 193
 194 static struct pwqr_task *pwqr_task_create(struct task_struct *task)
 195 {
 196         struct pwqr_task_bucket *b = task_hbucket(task);
 197         struct pwqr_task *pwqt;
 198
 199         pwqt = kmalloc(sizeof(*pwqt), GFP_KERNEL);
 200         if (pwqt == NULL)
 201                 return ERR_PTR(-ENOMEM);
 202
 203         preempt_notifier_init(&pwqt->notifier, &pwqr_preempt_running_ops);
 204         preempt_notifier_register(&pwqt->notifier);
 205         pwqt->task = task;
 206
 207         spin_lock(&b->lock);
 208         hlist_add_head(&pwqt->link, &b->tasks);
 209         spin_unlock(&b->lock);
 210
 211         return pwqt;
 212 }
 213
 214 __cold
 215 static void pwqr_task_detach(struct pwqr_task *pwqt, struct pwqr_sb *sb)
 216 {
 217         unsigned long flags;
 218
 219         pwqr_sb_lock_irqsave(sb, flags);
 220         sb->registered--;
 221         if (pwqt->notifier.ops == &pwqr_preempt_running_ops) {
 222                 __pwqr_sb_update_state(sb, -1);
 223         } else {
 224                 __pwqr_sb_update_state(sb, 0);
 225         }
 226         pwqr_sb_unlock_irqrestore(sb, flags);
 227         pwqr_sb_put(sb);
 228         pwqt->sb = NULL;
 229 }
 230
 231 __cold
 232 static void pwqr_task_attach(struct pwqr_task *pwqt, struct pwqr_sb *sb)
 233 {
 234         unsigned long flags;
 235
 236         pwqr_sb_lock_irqsave(sb, flags);
 237         pwqr_sb_get(pwqt->sb = sb);
 238         sb->registered++;
 239         __pwqr_sb_update_state(sb, 1);
 240         pwqr_sb_unlock_irqrestore(sb, flags);
 241 }
 242
 243 __cold
 244 static void pwqr_task_release(struct pwqr_task *pwqt, bool from_notifier)
 245 {
 246         struct pwqr_task_bucket *b = task_hbucket(pwqt->task);
 247
 248         spin_lock(&b->lock);
 249         hlist_del(&pwqt->link);
 250         spin_unlock(&b->lock);
 251         pwqt->notifier.ops = &pwqr_preempt_noop_ops;
 252
 253         if (from_notifier) {
 254                 /* When called from sched_{out,in}, it's not allowed to
 255                  * call preempt_notifier_unregister (or worse kfree())
 256                  *
 257                  * Though it's not a good idea to kfree() still registered
 258                  * callbacks if we're not dying, it'll panic on the next
 259                  * sched_{in,out} call.
 260                  */
 261                 BUG_ON(!(pwqt->task->state & TASK_DEAD));
 262                 kfree_rcu(pwqt, rcu);
 263         } else {
 264                 preempt_notifier_unregister(&pwqt->notifier);
 265                 kfree(pwqt);
 266         }
 267 }
 268
 269 static void pwqr_task_noop_sched_in(struct preempt_notifier *notifier, int cpu)
 270 {
 271 }
 272
 273 static void pwqr_task_noop_sched_out(struct preempt_notifier *notifier,
 274                                     struct task_struct *next)
 275 {
 276 }
 277
 278 static void pwqr_task_blocked_sched_in(struct preempt_notifier *notifier, int cpu)
 279 {
 280         struct pwqr_task *pwqt = container_of(notifier, struct pwqr_task, notifier);
 281         struct pwqr_sb   *sb   = pwqt->sb;
 282         unsigned long flags;
 283
 284         if (unlikely(sb->dead)) {
 285                 pwqr_task_detach(pwqt, sb);
 286                 pwqr_task_release(pwqt, true);
 287                 return;
 288         }
 289
 290         pwqt->notifier.ops = &pwqr_preempt_running_ops;
 291         pwqr_sb_lock_irqsave(sb, flags);
 292         __pwqr_sb_update_state(sb, 1);
 293         pwqr_sb_unlock_irqrestore(sb, flags);
 294 }
 295
 296 static void pwqr_task_sched_out(struct preempt_notifier *notifier,
 297                                struct task_struct *next)
 298 {
 299         struct pwqr_task    *pwqt = container_of(notifier, struct pwqr_task, notifier);
 300         struct pwqr_sb      *sb   = pwqt->sb;
 301         struct task_struct *p    = pwqt->task;
 302
 303         if (unlikely(p->state & TASK_DEAD) || unlikely(sb->dead)) {
 304                 pwqr_task_detach(pwqt, sb);
 305                 pwqr_task_release(pwqt, true);
 306                 return;
 307         }
 308         if (p->state == 0 || (p->state & (__TASK_STOPPED | __TASK_TRACED)))
 309                 return;
 310
 311         pwqt->notifier.ops = &pwqr_preempt_blocked_ops;
 312         /* see preempt.h: irq are disabled for sched_out */
 313         spin_lock(&sb->wqh.lock);
 314         __pwqr_sb_update_state(sb, -1);
 315         spin_unlock(&sb->wqh.lock);
 316 }
 317
 318 static struct preempt_ops __read_mostly pwqr_preempt_noop_ops = {
 319         .sched_in       = pwqr_task_noop_sched_in,
 320         .sched_out      = pwqr_task_noop_sched_out,
 321 };
 322
 323 static struct preempt_ops __read_mostly pwqr_preempt_running_ops = {
 324         .sched_in       = pwqr_task_noop_sched_in,
 325         .sched_out      = pwqr_task_sched_out,
 326 };
 327
 328 static struct preempt_ops __read_mostly pwqr_preempt_blocked_ops = {
 329         .sched_in       = pwqr_task_blocked_sched_in,
 330         .sched_out      = pwqr_task_sched_out,
 331 };
 332
 333 /*****************************************************************************
 334  * file descriptor
 335  */
 336 static int pwqr_open(struct inode *inode, struct file *filp)
 337 {
 338         struct pwqr_sb *sb;
 339
 340         sb = pwqr_sb_create();
 341         if (IS_ERR(sb))
 342                 return PTR_ERR(sb);
 343         filp->private_data = sb;
 344         return 0;
 345 }
 346
 347 static int pwqr_release(struct inode *inode, struct file *filp)
 348 {
 349         struct pwqr_sb *sb = filp->private_data;
 350         unsigned long flags;
 351
 352         pwqr_sb_lock_irqsave(sb, flags);
 353         sb->dead = true;
 354         pwqr_sb_unlock_irqrestore(sb, flags);
 355         wake_up_all(&sb->wqh);
 356         pwqr_sb_put(sb);
 357         return 0;
 358 }
 359
 360 static long
 361 do_pwqr_wait(struct pwqr_sb *sb, struct pwqr_task *pwqt,
 362             int is_wait, struct pwqr_ioc_wait __user *arg)
 363 {
 364         unsigned long flags;
 365         struct pwqr_ioc_wait wait;
 366         long rc = 0;
 367         u32 uval;
 368
 369         preempt_notifier_unregister(&pwqt->notifier);
 370
 371         if (is_wait && copy_from_user(&wait, arg, sizeof(wait))) {
 372                 rc = -EFAULT;
 373                 goto out;
 374         }
 375
 376         pwqr_sb_lock_irqsave(sb, flags);
 377         if (sb->running + sb->waiting <= sb->concurrency) {
 378                 if (is_wait) {
 379                         while (probe_kernel_address(wait.pwqr_uaddr, uval)) {
 380                                 pwqr_sb_unlock_irqrestore(sb, flags);
 381                                 rc = get_user(uval, (u32 *)wait.pwqr_uaddr);
 382                                 if (rc)
 383                                         goto out;
 384                                 pwqr_sb_lock_irqsave(sb, flags);
 385                         }
 386
 387                         if (uval != (u32)wait.pwqr_ticket) {
 388                                 rc = -EWOULDBLOCK;
 389                                 goto out_unlock;
 390                         }
 391                 } else {
 392                         goto out_unlock;
 393                 }
 394         }
 395
 396         /* @ see <wait_event_interruptible_exclusive_locked_irq> */
 397         if (likely(!sb->dead)) {
 398                 DEFINE_WAIT(__wait);
 399
 400                 __wait.flags |= WQ_FLAG_EXCLUSIVE;
 401
 402                 if (is_wait) {
 403                         sb->waiting++;
 404                         __add_wait_queue(&sb->wqh, &__wait);
 405                 } else {
 406                         sb->parked++;
 407                         __add_wait_queue_tail(&sb->wqh, &__wait);
 408                 }
 409                 __pwqr_sb_update_state(sb, -1);
 410                 set_current_state(TASK_INTERRUPTIBLE);
 411
 412                 do {
 413                         if (sb->overcommit_wakes)
 414                                 break;
 415                         if (signal_pending(current)) {
 416                                 rc = -ERESTARTSYS;
 417                                 break;
 418                         }
 419                         spin_unlock_irq(&sb->wqh.lock);
 420                         schedule();
 421                         spin_lock_irq(&sb->wqh.lock);
 422                         if (is_wait)
 423                                 break;
 424                         if (sb->running + sb->waiting < sb->concurrency)
 425                                 break;
 426                 } while (likely(!sb->dead));
 427
 428                 __remove_wait_queue(&sb->wqh, &__wait);
 429                 __set_current_state(TASK_RUNNING);
 430
 431                 if (is_wait) {
 432                         sb->waiting--;
 433                 } else {
 434                         sb->parked--;
 435                 }
 436                 __pwqr_sb_update_state(sb, 1);
 437                 if (sb->overcommit_wakes)
 438                         sb->overcommit_wakes--;
 439                 if (sb->waiting + sb->running > sb->concurrency)
 440                         rc = -EDQUOT;
 441         }
 442
 443 out_unlock:
 444         if (unlikely(sb->dead))
 445                 rc = -EBADFD;
 446         pwqr_sb_unlock_irqrestore(sb, flags);
 447 out:
 448         preempt_notifier_register(&pwqt->notifier);
 449         return rc;
 450 }
 451
 452 static long do_pwqr_unregister(struct pwqr_sb *sb, struct pwqr_task *pwqt)
 453 {
 454         if (!pwqt)
 455                 return -EINVAL;
 456         if (pwqt->sb != sb)
 457                 return -ENOENT;
 458         pwqr_task_detach(pwqt, sb);
 459         pwqr_task_release(pwqt, false);
 460         return 0;
 461 }
 462
 463 static long do_pwqr_set_conc(struct pwqr_sb *sb, int conc)
 464 {
 465         long old_conc = sb->concurrency;
 466         unsigned long flags;
 467
 468         pwqr_sb_lock_irqsave(sb, flags);
 469         if (conc <= 0)
 470                 conc = num_online_cpus();
 471         if (conc != old_conc) {
 472                 sb->concurrency = conc;
 473                 __pwqr_sb_update_state(sb, 0);
 474         }
 475         pwqr_sb_unlock_irqrestore(sb, flags);
 476
 477         return old_conc;
 478 }
 479
 480 static long do_pwqr_wake(struct pwqr_sb *sb, int oc, int count)
 481 {
 482         unsigned long flags;
 483         int nwake;
 484
 485         if (count < 0)
 486                 return -EINVAL;
 487
 488         pwqr_sb_lock_irqsave(sb, flags);
 489
 490         if (oc) {
 491                 nwake = sb->waiting + sb->parked - sb->overcommit_wakes;
 492                 if (count > nwake) {
 493                         count = nwake;
 494                 } else {
 495                         nwake = count;
 496                 }
 497                 sb->overcommit_wakes += count;
 498         } else if (sb->running + sb->overcommit_wakes < sb->concurrency) {
 499                 nwake = sb->concurrency - sb->overcommit_wakes - sb->running;
 500                 if (nwake > sb->waiting + sb->parked - sb->overcommit_wakes) {
 501                         nwake = sb->waiting + sb->parked -
 502                                 sb->overcommit_wakes;
 503                 }
 504                 if (count > nwake) {
 505                         count = nwake;
 506                 } else {
 507                         nwake = count;
 508                 }
 509         } else {
 510                 /*
 511                  * This codepath deserves an explanation: waking the thread
 512                  * "for real" would overcommit, though userspace KNOWS there
 513                  * is at least one waiting thread. Such threads are threads
 514                  * that are "quarantined".
 515                  *
 516                  * Quarantined threads are woken up one by one, to allow a
 517                  * slow ramp down, trying to minimize "waiting" <-> "parked"
 518                  * flip-flops, no matter how many wakes have been asked.
 519                  *
 520                  * Since releasing one quarantined thread will wake up a
 521                  * thread that will (almost) straight go to parked mode, lie
 522                  * to userland about the fact that we unblocked that thread,
 523                  * and return 0.
 524                  *
 525                  * Though if we're already waking all waiting threads for
 526                  * overcommitting jobs, well, we don't need that.
 527                  */
 528                 count = 0;
 529                 nwake = sb->waiting > sb->overcommit_wakes;
 530         }
 531         while (nwake-- > 0)
 532                 wake_up_locked(&sb->wqh);
 533         pwqr_sb_unlock_irqrestore(sb, flags);
 534
 535         return count;
 536 }
 537
 538 static long pwqr_ioctl(struct file *filp, unsigned command, unsigned long arg)
 539 {
 540         struct pwqr_sb      *sb   = filp->private_data;
 541         struct task_struct *task = current;
 542         struct pwqr_task    *pwqt;
 543         int rc = 0;
 544
 545         if (sb->tgid != current->tgid)
 546                 return -EBADFD;
 547
 548         switch (command) {
 549         case PWQR_GET_CONC:
 550                 return sb->concurrency;
 551         case PWQR_SET_CONC:
 552                 return do_pwqr_set_conc(sb, (int)arg);
 553
 554         case PWQR_WAKE:
 555         case PWQR_WAKE_OC:
 556                 return do_pwqr_wake(sb, command == PWQR_WAKE_OC, (int)arg);
 557
 558         case PWQR_WAIT:
 559         case PWQR_PARK:
 560         case PWQR_REGISTER:
 561         case PWQR_UNREGISTER:
 562                 break;
 563         default:
 564                 return -EINVAL;
 565         }
 566
 567         pwqt = pwqr_task_find(task);
 568         if (command == PWQR_UNREGISTER)
 569                 return do_pwqr_unregister(sb, pwqt);
 570
 571         if (pwqt == NULL) {
 572                 pwqt = pwqr_task_create(task);
 573                 if (IS_ERR(pwqt))
 574                         return PTR_ERR(pwqt);
 575                 pwqr_task_attach(pwqt, sb);
 576         } else if (unlikely(pwqt->sb != sb)) {
 577                 pwqr_task_detach(pwqt, pwqt->sb);
 578                 pwqr_task_attach(pwqt, sb);
 579         }
 580
 581         switch (command) {
 582         case PWQR_WAIT:
 583                 rc = do_pwqr_wait(sb, pwqt, true, (struct pwqr_ioc_wait __user *)arg);
 584                 break;
 585         case PWQR_PARK:
 586                 rc = do_pwqr_wait(sb, pwqt, false, NULL);
 587                 break;
 588         }
 589
 590         if (unlikely(sb->dead)) {
 591                 pwqr_task_detach(pwqt, pwqt->sb);
 592                 return -EBADFD;
 593         }
 594         return rc;
 595 }
 596
 597 static const struct file_operations pwqr_dev_fops = {
 598         .owner          = THIS_MODULE,
 599         .open           = pwqr_open,
 600         .release        = pwqr_release,
 601         .unlocked_ioctl = pwqr_ioctl,
 602 #ifdef CONFIG_COMPAT
 603         .compat_ioctl   = pwqr_ioctl,
 604 #endif
 605 };
 606
 607 /*****************************************************************************
 608  * module
 609  */
 610 static int __init pwqr_start(void)
 611 {
 612         int i;
 613
 614         for (i = 0; i < PWQR_HASH_SIZE; i++) {
 615                 spin_lock_init(&pwqr_tasks_hash[i].lock);
 616                 INIT_HLIST_HEAD(&pwqr_tasks_hash[i].tasks);
 617         }
 618
 619         /* Register as a character device */
 620         pwqr_major = register_chrdev(0, "pwqr", &pwqr_dev_fops);
 621         if (pwqr_major < 0) {
 622                 printk(KERN_ERR "pwqr: register_chrdev() failed\n");
 623                 return pwqr_major;
 624         }
 625
 626         /* Create a device node */
 627         pwqr_class = class_create(THIS_MODULE, PWQR_DEVICE_NAME);
 628         if (IS_ERR(pwqr_class)) {
 629                 printk(KERN_ERR "pwqr: Error creating raw class\n");
 630                 unregister_chrdev(pwqr_major, PWQR_DEVICE_NAME);
 631                 return PTR_ERR(pwqr_class);
 632         }
 633         device_create(pwqr_class, NULL, MKDEV(pwqr_major, 0), NULL, PWQR_DEVICE_NAME);
 634         printk(KERN_INFO "pwqr: PThreads Work Queues Regulator v1 loaded");
 635         return 0;
 636 }
 637
 638 static void __exit pwqr_end(void)
 639 {
 640         rcu_barrier();
 641         device_destroy(pwqr_class, MKDEV(pwqr_major, 0));
 642         class_destroy(pwqr_class);
 643         unregister_chrdev(pwqr_major, PWQR_DEVICE_NAME);
 644 }
 645
 646 module_init(pwqr_start);
 647 module_exit(pwqr_end);
 648
 649 MODULE_LICENSE("GPL");
 650 MODULE_AUTHOR("Pierre Habouzit <pierre.habouzit@intersec.com>");
 651 MODULE_DESCRIPTION("PThreads Work Queues Regulator");
 652
 653 // vim:noet:sw=8:cinoptions+=\:0,L-1,=1s: