[mirror_frr.git] / lib / workqueue.c

/* 
 * Quagga Work Queue Support.
 *
 * Copyright (C) 2005 Sun Microsystems, Inc.
 *
 * This file is part of GNU Zebra.
 *
 * Quagga is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License as published by the
 * Free Software Foundation; either version 2, or (at your option) any
 * later version.
 *
 * Quagga is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with Quagga; see the file COPYING.  If not, write to the Free
 * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
 * 02111-1307, USA.  
 */

#include <lib/zebra.h>
#include "thread.h"
#include "memory.h"
#include "workqueue.h"
#include "linklist.h"
#include "command.h"
#include "log.h"

/* master list of work_queues */
static struct list _work_queues;
/* pointer primarily to avoid an otherwise harmless warning on
 * ALL_LIST_ELEMENTS_RO
 */
static struct list *work_queues = &_work_queues;

#define WORK_QUEUE_MIN_GRANULARITY 1

static struct work_queue_item *
work_queue_item_new (struct work_queue *wq)
{
  struct work_queue_item *item;
  assert (wq);

  item = XCALLOC (MTYPE_WORK_QUEUE_ITEM, 
                  sizeof (struct work_queue_item));
  
  return item;
}

static void
work_queue_item_free (struct work_queue_item *item)
{
  XFREE (MTYPE_WORK_QUEUE_ITEM, item);
  return;
}

/* create new work queue */
struct work_queue *
work_queue_new (struct thread_master *m, const char *queue_name)
{
  struct work_queue *new;
  
  new = XCALLOC (MTYPE_WORK_QUEUE, sizeof (struct work_queue));

  if (new == NULL)
    return new;
  
  new->name = XSTRDUP (MTYPE_WORK_QUEUE_NAME, queue_name);
  new->master = m;
  SET_FLAG (new->flags, WQ_UNPLUGGED);
  
  if ( (new->items = list_new ()) == NULL)
    {
      XFREE (MTYPE_WORK_QUEUE_NAME, new->name);
      XFREE (MTYPE_WORK_QUEUE, new);
      
      return NULL;
    }
  
  new->items->del = (void (*)(void *)) work_queue_item_free;  
  
  listnode_add (work_queues, new);
  
  new->cycles.granularity = WORK_QUEUE_MIN_GRANULARITY;

  /* Default values, can be overriden by caller */
  new->spec.hold = WORK_QUEUE_DEFAULT_HOLD;
  new->spec.yield = THREAD_YIELD_TIME_SLOT;
    
  return new;
}

void
work_queue_free (struct work_queue *wq)
{
  if (wq->thread != NULL)
    thread_cancel(wq->thread);
  
  /* list_delete frees items via callback */
  list_delete (wq->items);
  listnode_delete (work_queues, wq);
  
  XFREE (MTYPE_WORK_QUEUE_NAME, wq->name);
  XFREE (MTYPE_WORK_QUEUE, wq);
  return;
}

bool
work_queue_is_scheduled (struct work_queue *wq)
{
  return (wq->thread != NULL);
}

static int
work_queue_schedule (struct work_queue *wq, unsigned int delay)
{
  /* if appropriate, schedule work queue thread */
  if ( CHECK_FLAG (wq->flags, WQ_UNPLUGGED)
       && (wq->thread == NULL)
       && (listcount (wq->items) > 0) )
    {
      wq->thread = thread_add_background (wq->master, work_queue_run, 
                                          wq, delay);
      /* set thread yield time, if needed */
      if (wq->thread && wq->spec.yield != THREAD_YIELD_TIME_SLOT)
        thread_set_yield_time (wq->thread, wq->spec.yield);
      return 1;
    }
  else
    return 0;
}
  
void
work_queue_add (struct work_queue *wq, void *data)
{
  struct work_queue_item *item;
  
  assert (wq);

  if (!(item = work_queue_item_new (wq)))
    {
      zlog_err ("%s: unable to get new queue item", __func__);
      return;
    }
  
  item->data = data;
  listnode_add (wq->items, item);
  
  work_queue_schedule (wq, wq->spec.hold);
  
  return;
}

static void
work_queue_item_remove (struct work_queue *wq, struct listnode *ln)
{
  struct work_queue_item *item = listgetdata (ln);

  assert (item && item->data);

  /* call private data deletion callback if needed */  
  if (wq->spec.del_item_data)
    wq->spec.del_item_data (wq, item->data);

  list_delete_node (wq->items, ln);
  work_queue_item_free (item);
  
  return;
}

static void
work_queue_item_requeue (struct work_queue *wq, struct listnode *ln)
{
  LISTNODE_DETACH (wq->items, ln);
  LISTNODE_ATTACH (wq->items, ln); /* attach to end of list */
}

DEFUN(show_work_queues,
      show_work_queues_cmd,
      "show work-queues",
      SHOW_STR
      "Work Queue information\n")
{
  struct listnode *node;
  struct work_queue *wq;
  
  vty_out (vty, 
           "%c %8s %5s %8s %8s %21s%s",
           ' ', "List","(ms) ","Q. Runs","Yields","Cycle Counts   ",
           VTY_NEWLINE);
  vty_out (vty,
           "%c %8s %5s %8s %8s %7s %6s %8s %6s %s%s",
           'P',
           "Items",
           "Hold",
           "Total","Total",
           "Best","Gran.","Total","Avg.",
           "Name", 
           VTY_NEWLINE);
 
  for (ALL_LIST_ELEMENTS_RO (work_queues, node, wq))
    {
      vty_out (vty,"%c %8d %5d %8ld %8ld %7d %6d %8ld %6u %s%s",
               (CHECK_FLAG (wq->flags, WQ_UNPLUGGED) ? ' ' : 'P'),
               listcount (wq->items),
               wq->spec.hold,
               wq->runs, wq->yields,
               wq->cycles.best, wq->cycles.granularity, wq->cycles.total,
                 (wq->runs) ? 
                   (unsigned int) (wq->cycles.total / wq->runs) : 0,
               wq->name,
               VTY_NEWLINE);
    }
    
  return CMD_SUCCESS;
}

/* 'plug' a queue: Stop it from being scheduled,
 * ie: prevent the queue from draining.
 */
void
work_queue_plug (struct work_queue *wq)
{
  if (wq->thread)
    thread_cancel (wq->thread);
  
  wq->thread = NULL;
  
  UNSET_FLAG (wq->flags, WQ_UNPLUGGED);
}

/* unplug queue, schedule it again, if appropriate
 * Ie: Allow the queue to be drained again
 */
void
work_queue_unplug (struct work_queue *wq)
{
  SET_FLAG (wq->flags, WQ_UNPLUGGED);

  /* if thread isnt already waiting, add one */
  work_queue_schedule (wq, wq->spec.hold);
}

/* timer thread to process a work queue
 * will reschedule itself if required,
 * otherwise work_queue_item_add 
 */
int
work_queue_run (struct thread *thread)
{
  struct work_queue *wq;
  struct work_queue_item *item;
  wq_item_status ret;
  unsigned int cycles = 0;
  struct listnode *node, *nnode;
  char yielded = 0;

  wq = THREAD_ARG (thread);
  wq->thread = NULL;

  assert (wq && wq->items);

  /* calculate cycle granularity:
   * list iteration == 1 run
   * listnode processing == 1 cycle
   * granularity == # cycles between checks whether we should yield.
   *
   * granularity should be > 0, and can increase slowly after each run to
   * provide some hysteris, but not past cycles.best or 2*cycles.
   *
   * Best: starts low, can only increase
   *
   * Granularity: starts at WORK_QUEUE_MIN_GRANULARITY, can be decreased 
   *              if we run to end of time slot, can increase otherwise 
   *              by a small factor.
   *
   * We could use just the average and save some work, however we want to be
   * able to adjust quickly to CPU pressure. Average wont shift much if
   * daemon has been running a long time.
   */
   if (wq->cycles.granularity == 0)
     wq->cycles.granularity = WORK_QUEUE_MIN_GRANULARITY;

  for (ALL_LIST_ELEMENTS (wq->items, node, nnode, item))
  {
    assert (item && item->data);
    
    /* dont run items which are past their allowed retries */
    if (item->ran > wq->spec.max_retries)
      {
        /* run error handler, if any */
	if (wq->spec.errorfunc)
	  wq->spec.errorfunc (wq, item->data);
	work_queue_item_remove (wq, node);
	continue;
      }

    /* run and take care of items that want to be retried immediately */
    do
      {
        ret = wq->spec.workfunc (wq, item->data);
        item->ran++;
      }
    while ((ret == WQ_RETRY_NOW) 
           && (item->ran < wq->spec.max_retries));

    switch (ret)
      {
      case WQ_QUEUE_BLOCKED:
        {
          /* decrement item->ran again, cause this isn't an item
           * specific error, and fall through to WQ_RETRY_LATER
           */
          item->ran--;
        }
      case WQ_RETRY_LATER:
	{
	  goto stats;
	}
      case WQ_REQUEUE:
	{
	  item->ran--;
	  work_queue_item_requeue (wq, node);
      /* If a single node is being used with a meta-queue (e.g., zebra),
       * update the next node as we don't want to exit the thread and
       * reschedule it after every node. By definition, WQ_REQUEUE is
       * meant to continue the processing; the yield logic will kick in
       * to terminate the thread when time has exceeded.
       */
      if (nnode == NULL)
        nnode = node;
	  break;
	}
      case WQ_RETRY_NOW:
        /* a RETRY_NOW that gets here has exceeded max_tries, same as ERROR */
      case WQ_ERROR:
	{
	  if (wq->spec.errorfunc)
	    wq->spec.errorfunc (wq, item);
	}
	/* fall through here is deliberate */
      case WQ_SUCCESS:
      default:
	{
	  work_queue_item_remove (wq, node);
	  break;
	}
      }

    /* completed cycle */
    cycles++;

    /* test if we should yield */
    if ( !(cycles % wq->cycles.granularity) 
        && thread_should_yield (thread))
      {
        yielded = 1;
        goto stats;
      }
  }

stats:

#define WQ_HYSTERESIS_FACTOR 4

  /* we yielded, check whether granularity should be reduced */
  if (yielded && (cycles < wq->cycles.granularity))
    {
      wq->cycles.granularity = ((cycles > 0) ? cycles
                                             : WORK_QUEUE_MIN_GRANULARITY);
    }
  /* otherwise, should granularity increase? */
  else if (cycles >= (wq->cycles.granularity))
    {
      if (cycles > wq->cycles.best)
        wq->cycles.best = cycles;

      /* along with yielded check, provides hysteresis for granularity */
      if (cycles > (wq->cycles.granularity * WQ_HYSTERESIS_FACTOR
                                           * WQ_HYSTERESIS_FACTOR))
        wq->cycles.granularity *= WQ_HYSTERESIS_FACTOR; /* quick ramp-up */
      else if (cycles > (wq->cycles.granularity * WQ_HYSTERESIS_FACTOR))
        wq->cycles.granularity += WQ_HYSTERESIS_FACTOR;
    }
#undef WQ_HYSTERIS_FACTOR
  
  wq->runs++;
  wq->cycles.total += cycles;
  if (yielded)
    wq->yields++;

#if 0
  printf ("%s: cycles %d, new: best %d, worst %d\n",
            __func__, cycles, wq->cycles.best, wq->cycles.granularity);
#endif
  
  /* Is the queue done yet? If it is, call the completion callback. */
  if (listcount (wq->items) > 0)
    work_queue_schedule (wq, 0);
  else if (wq->spec.completion_func)
    wq->spec.completion_func (wq);
  
  return 0;
}
Commit	Line	Data
354d119a	1	/*
	2	* Quagga Work Queue Support.
	3	*
	4	* Copyright (C) 2005 Sun Microsystems, Inc.
	5	*
	6	* This file is part of GNU Zebra.
	7	*
	8	* Quagga is free software; you can redistribute it and/or modify it
	9	* under the terms of the GNU General Public License as published by the
	10	* Free Software Foundation; either version 2, or (at your option) any
	11	* later version.
	12	*
	13	* Quagga is distributed in the hope that it will be useful, but
	14	* WITHOUT ANY WARRANTY; without even the implied warranty of
	15	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
	16	* General Public License for more details.
	17	*
	18	* You should have received a copy of the GNU General Public License
	19	* along with Quagga; see the file COPYING. If not, write to the Free
	20	* Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
	21	* 02111-1307, USA.
	22	*/
	23
	24	#include <lib/zebra.h>
	25	#include "thread.h"
	26	#include "memory.h"
	27	#include "workqueue.h"
	28	#include "linklist.h"
	29	#include "command.h"
	30	#include "log.h"
	31
	32	/* master list of work_queues */
24873f0c	33	static struct list _work_queues;
1f9a9fff	34	/* pointer primarily to avoid an otherwise harmless warning on
24873f0c DS	35	* ALL_LIST_ELEMENTS_RO
	36	*/
	37	static struct list *work_queues = &_work_queues;
354d119a	38
	39	#define WORK_QUEUE_MIN_GRANULARITY 1
	40
	41	static struct work_queue_item *
	42	work_queue_item_new (struct work_queue *wq)
	43	{
	44	struct work_queue_item *item;
	45	assert (wq);
	46
	47	item = XCALLOC (MTYPE_WORK_QUEUE_ITEM,
	48	sizeof (struct work_queue_item));
	49
	50	return item;
	51	}
	52
	53	static void
	54	work_queue_item_free (struct work_queue_item *item)
	55	{
	56	XFREE (MTYPE_WORK_QUEUE_ITEM, item);
	57	return;
	58	}
	59
	60	/* create new work queue */
	61	struct work_queue *
	62	work_queue_new (struct thread_master m, const char queue_name)
	63	{
	64	struct work_queue *new;
	65
	66	new = XCALLOC (MTYPE_WORK_QUEUE, sizeof (struct work_queue));
	67
	68	if (new == NULL)
	69	return new;
	70
	71	new->name = XSTRDUP (MTYPE_WORK_QUEUE_NAME, queue_name);
	72	new->master = m;
6ce80bdb	73	SET_FLAG (new->flags, WQ_UNPLUGGED);
354d119a	74
	75	if ( (new->items = list_new ()) == NULL)
	76	{
354d119a	77	XFREE (MTYPE_WORK_QUEUE_NAME, new->name);
	78	XFREE (MTYPE_WORK_QUEUE, new);
	79
	80	return NULL;
	81	}
	82
	83	new->items->del = (void ()(void )) work_queue_item_free;
	84
24873f0c	85	listnode_add (work_queues, new);
354d119a	86
354d119a	87	new->cycles.granularity = WORK_QUEUE_MIN_GRANULARITY;
190880dc	88
190880dc	89	/* Default values, can be overriden by caller */
190880dc	90	new->spec.hold = WORK_QUEUE_DEFAULT_HOLD;
50596be0	91	new->spec.yield = THREAD_YIELD_TIME_SLOT;
190880dc	92
354d119a	93	return new;
	94	}
	95
	96	void
	97	work_queue_free (struct work_queue *wq)
	98	{
acde4b86 SH	99	if (wq->thread != NULL)
	100	thread_cancel(wq->thread);
	101
354d119a	102	/* list_delete frees items via callback */
354d119a	103	list_delete (wq->items);
24873f0c	104	listnode_delete (work_queues, wq);
354d119a	105
	106	XFREE (MTYPE_WORK_QUEUE_NAME, wq->name);
	107	XFREE (MTYPE_WORK_QUEUE, wq);
	108	return;
	109	}
	110
86582682 PJ	111	bool
	112	work_queue_is_scheduled (struct work_queue *wq)
	113	{
	114	return (wq->thread != NULL);
	115	}
	116
f63f06da	117	static int
269d74fd	118	work_queue_schedule (struct work_queue *wq, unsigned int delay)
	119	{
	120	/* if appropriate, schedule work queue thread */
6ce80bdb	121	if ( CHECK_FLAG (wq->flags, WQ_UNPLUGGED)
269d74fd	122	&& (wq->thread == NULL)
	123	&& (listcount (wq->items) > 0) )
	124	{
	125	wq->thread = thread_add_background (wq->master, work_queue_run,
	126	wq, delay);
50596be0 DS	127	/* set thread yield time, if needed */
	128	if (wq->thread && wq->spec.yield != THREAD_YIELD_TIME_SLOT)
	129	thread_set_yield_time (wq->thread, wq->spec.yield);
269d74fd	130	return 1;
	131	}
	132	else
	133	return 0;
	134	}
	135
354d119a	136	void
	137	work_queue_add (struct work_queue wq, void data)
	138	{
	139	struct work_queue_item *item;
	140
	141	assert (wq);
	142
	143	if (!(item = work_queue_item_new (wq)))
	144	{
	145	zlog_err ("%s: unable to get new queue item", __func__);
	146	return;
	147	}
	148
	149	item->data = data;
e96f9203	150	listnode_add (wq->items, item);
354d119a	151
306d8890	152	work_queue_schedule (wq, wq->spec.hold);
354d119a	153
	154	return;
	155	}
	156
	157	static void
	158	work_queue_item_remove (struct work_queue wq, struct listnode ln)
	159	{
	160	struct work_queue_item *item = listgetdata (ln);
	161
	162	assert (item && item->data);
	163
	164	/* call private data deletion callback if needed */
	165	if (wq->spec.del_item_data)
889e9311	166	wq->spec.del_item_data (wq, item->data);
354d119a	167
	168	list_delete_node (wq->items, ln);
	169	work_queue_item_free (item);
	170
	171	return;
	172	}
	173
	174	static void
	175	work_queue_item_requeue (struct work_queue wq, struct listnode ln)
	176	{
	177	LISTNODE_DETACH (wq->items, ln);
	178	LISTNODE_ATTACH (wq->items, ln); /* attach to end of list */
	179	}
	180
	181	DEFUN(show_work_queues,
	182	show_work_queues_cmd,
	183	"show work-queues",
	184	SHOW_STR
	185	"Work Queue information\n")
	186	{
	187	struct listnode *node;
	188	struct work_queue *wq;
354d119a	189
354d119a	190	vty_out (vty,
50596be0 DS	191	"%c %8s %5s %8s %8s %21s%s",
50596be0 DS	192	' ', "List","(ms) ","Q. Runs","Yields","Cycle Counts ",
354d119a	193	VTY_NEWLINE);
354d119a	194	vty_out (vty,
50596be0	195	"%c %8s %5s %8s %8s %7s %6s %8s %6s %s%s",
306d8890	196	'P',
354d119a	197	"Items",
306d8890	198	"Hold",
50596be0 DS	199	"Total","Total",
50596be0 DS	200	"Best","Gran.","Total","Avg.",
354d119a	201	"Name",
	202	VTY_NEWLINE);
	203
24873f0c	204	for (ALL_LIST_ELEMENTS_RO (work_queues, node, wq))
354d119a	205	{
50596be0	206	vty_out (vty,"%c %8d %5d %8ld %8ld %7d %6d %8ld %6u %s%s",
6ce80bdb	207	(CHECK_FLAG (wq->flags, WQ_UNPLUGGED) ? ' ' : 'P'),
354d119a	208	listcount (wq->items),
306d8890	209	wq->spec.hold,
50596be0 DS	210	wq->runs, wq->yields,
50596be0 DS	211	wq->cycles.best, wq->cycles.granularity, wq->cycles.total,
84369684	212	(wq->runs) ?
84369684	213	(unsigned int) (wq->cycles.total / wq->runs) : 0,
354d119a	214	wq->name,
	215	VTY_NEWLINE);
	216	}
	217
	218	return CMD_SUCCESS;
	219	}
	220
269d74fd	221	/* 'plug' a queue: Stop it from being scheduled,
	222	* ie: prevent the queue from draining.
	223	*/
	224	void
	225	work_queue_plug (struct work_queue *wq)
	226	{
	227	if (wq->thread)
	228	thread_cancel (wq->thread);
	229
	230	wq->thread = NULL;
	231
6ce80bdb	232	UNSET_FLAG (wq->flags, WQ_UNPLUGGED);
269d74fd	233	}
	234
	235	/* unplug queue, schedule it again, if appropriate
	236	* Ie: Allow the queue to be drained again
	237	*/
	238	void
	239	work_queue_unplug (struct work_queue *wq)
	240	{
6ce80bdb	241	SET_FLAG (wq->flags, WQ_UNPLUGGED);
269d74fd	242
269d74fd	243	/* if thread isnt already waiting, add one */
306d8890	244	work_queue_schedule (wq, wq->spec.hold);
269d74fd	245	}
269d74fd	246
354d119a	247	/* timer thread to process a work queue
	248	* will reschedule itself if required,
	249	* otherwise work_queue_item_add
	250	*/
	251	int
	252	work_queue_run (struct thread *thread)
	253	{
	254	struct work_queue *wq;
	255	struct work_queue_item *item;
	256	wq_item_status ret;
	257	unsigned int cycles = 0;
	258	struct listnode node, nnode;
	259	char yielded = 0;
	260
	261	wq = THREAD_ARG (thread);
	262	wq->thread = NULL;
	263
	264	assert (wq && wq->items);
	265
	266	/* calculate cycle granularity:
50596be0 DS	267	* list iteration == 1 run
50596be0 DS	268	* listnode processing == 1 cycle
354d119a	269	* granularity == # cycles between checks whether we should yield.
	270	*
	271	* granularity should be > 0, and can increase slowly after each run to
	272	* provide some hysteris, but not past cycles.best or 2*cycles.
	273	*
	274	* Best: starts low, can only increase
	275	*
213d8dad PJ	276	* Granularity: starts at WORK_QUEUE_MIN_GRANULARITY, can be decreased
	277	* if we run to end of time slot, can increase otherwise
	278	* by a small factor.
354d119a	279	*
	280	* We could use just the average and save some work, however we want to be
	281	* able to adjust quickly to CPU pressure. Average wont shift much if
	282	* daemon has been running a long time.
	283	*/
	284	if (wq->cycles.granularity == 0)
	285	wq->cycles.granularity = WORK_QUEUE_MIN_GRANULARITY;
	286
	287	for (ALL_LIST_ELEMENTS (wq->items, node, nnode, item))
	288	{
	289	assert (item && item->data);
	290
	291	/* dont run items which are past their allowed retries */
84369684	292	if (item->ran > wq->spec.max_retries)
354d119a	293	{
	294	/* run error handler, if any */
	295	if (wq->spec.errorfunc)
	296	wq->spec.errorfunc (wq, item->data);
	297	work_queue_item_remove (wq, node);
	298	continue;
	299	}
	300
	301	/* run and take care of items that want to be retried immediately */
	302	do
	303	{
889e9311	304	ret = wq->spec.workfunc (wq, item->data);
84369684	305	item->ran++;
354d119a	306	}
354d119a	307	while ((ret == WQ_RETRY_NOW)
84369684	308	&& (item->ran < wq->spec.max_retries));
354d119a	309
	310	switch (ret)
	311	{
269d74fd	312	case WQ_QUEUE_BLOCKED:
	313	{
	314	/* decrement item->ran again, cause this isn't an item
	315	* specific error, and fall through to WQ_RETRY_LATER
	316	*/
	317	item->ran--;
	318	}
354d119a	319	case WQ_RETRY_LATER:
354d119a	320	{
354d119a	321	goto stats;
	322	}
	323	case WQ_REQUEUE:
	324	{
e96f9203	325	item->ran--;
354d119a	326	work_queue_item_requeue (wq, node);
50596be0 DS	327	/* If a single node is being used with a meta-queue (e.g., zebra),
	328	* update the next node as we don't want to exit the thread and
	329	* reschedule it after every node. By definition, WQ_REQUEUE is
	330	* meant to continue the processing; the yield logic will kick in
	331	* to terminate the thread when time has exceeded.
	332	*/
	333	if (nnode == NULL)
	334	nnode = node;
354d119a	335	break;
	336	}
	337	case WQ_RETRY_NOW:
269d74fd	338	/* a RETRY_NOW that gets here has exceeded max_tries, same as ERROR */
354d119a	339	case WQ_ERROR:
	340	{
	341	if (wq->spec.errorfunc)
	342	wq->spec.errorfunc (wq, item);
	343	}
	344	/* fall through here is deliberate */
	345	case WQ_SUCCESS:
	346	default:
	347	{
	348	work_queue_item_remove (wq, node);
	349	break;
	350	}
	351	}
	352
	353	/* completed cycle */
	354	cycles++;
	355
	356	/* test if we should yield */
	357	if ( !(cycles % wq->cycles.granularity)
	358	&& thread_should_yield (thread))
	359	{
	360	yielded = 1;
	361	goto stats;
	362	}
	363	}
	364
	365	stats:
	366
3322055b	367	#define WQ_HYSTERESIS_FACTOR 4
354d119a	368
	369	/* we yielded, check whether granularity should be reduced */
	370	if (yielded && (cycles < wq->cycles.granularity))
	371	{
50596be0	372	wq->cycles.granularity = ((cycles > 0) ? cycles
354d119a	373	: WORK_QUEUE_MIN_GRANULARITY);
354d119a	374	}
3322055b PJ	375	/* otherwise, should granularity increase? */
3322055b PJ	376	else if (cycles >= (wq->cycles.granularity))
354d119a	377	{
	378	if (cycles > wq->cycles.best)
	379	wq->cycles.best = cycles;
50596be0	380
3322055b PJ	381	/* along with yielded check, provides hysteresis for granularity */
	382	if (cycles > (wq->cycles.granularity * WQ_HYSTERESIS_FACTOR
	383	* WQ_HYSTERESIS_FACTOR))
	384	wq->cycles.granularity = WQ_HYSTERESIS_FACTOR; / quick ramp-up */
	385	else if (cycles > (wq->cycles.granularity * WQ_HYSTERESIS_FACTOR))
	386	wq->cycles.granularity += WQ_HYSTERESIS_FACTOR;
354d119a	387	}
	388	#undef WQ_HYSTERIS_FACTOR
	389
	390	wq->runs++;
	391	wq->cycles.total += cycles;
50596be0 DS	392	if (yielded)
50596be0 DS	393	wq->yields++;
354d119a	394
	395	#if 0
	396	printf ("%s: cycles %d, new: best %d, worst %d\n",
	397	__func__, cycles, wq->cycles.best, wq->cycles.granularity);
	398	#endif
	399
269d74fd	400	/* Is the queue done yet? If it is, call the completion callback. */
354d119a	401	if (listcount (wq->items) > 0)
306d8890	402	work_queue_schedule (wq, 0);
	403	else if (wq->spec.completion_func)
	404	wq->spec.completion_func (wq);
269d74fd	405
354d119a	406	return 0;
354d119a	407	}