[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 this program; see the file COPYING; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
 */

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

DEFINE_MTYPE(LIB, WORK_QUEUE, "Work queue")
DEFINE_MTYPE_STATIC(LIB, WORK_QUEUE_ITEM, "Work queue item")
DEFINE_MTYPE_STATIC(LIB, WORK_QUEUE_NAME, "Work queue name string")

/* 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 = NULL;
		thread_add_timer_msec(wq->master, work_queue_run, wq, delay,
				      &wq->thread);
		/* 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\n", ' ', "List", "(ms) ",
		"Q. Runs", "Yields", "Cycle Counts   ");
	vty_out(vty, "%c %8s %5s %8s %8s %7s %6s %8s %6s %s\n", 'P', "Items",
		"Hold", "Total", "Total", "Best", "Gran.", "Total", "Avg.",
		"Name");

	for (ALL_LIST_ELEMENTS_RO(work_queues, node, wq)) {
		vty_out(vty, "%c %8d %5d %8ld %8ld %7d %6d %8ld %6u %s\n",
			(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);
	}

	return CMD_SUCCESS;
}

void workqueue_cmd_init(void)
{
	install_element(VIEW_NODE, &show_work_queues_cmd);
}

/* '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);
		}
		/* fallthru */
		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
d62a17ae	1	/*
354d119a	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	*
896014f4 DL	18	* You should have received a copy of the GNU General Public License along
	19	* with this program; see the file COPYING; if not, write to the Free Software
	20	* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
354d119a	21	*/
354d119a	22
7a2fbbf0	23	#include <zebra.h>
354d119a	24	#include "thread.h"
	25	#include "memory.h"
	26	#include "workqueue.h"
	27	#include "linklist.h"
	28	#include "command.h"
	29	#include "log.h"
	30
d62a17ae	31	DEFINE_MTYPE(LIB, WORK_QUEUE, "Work queue")
4a1ab8e4 DL	32	DEFINE_MTYPE_STATIC(LIB, WORK_QUEUE_ITEM, "Work queue item")
	33	DEFINE_MTYPE_STATIC(LIB, WORK_QUEUE_NAME, "Work queue name string")
	34
354d119a	35	/* master list of work_queues */
24873f0c	36	static struct list _work_queues;
1f9a9fff	37	/* pointer primarily to avoid an otherwise harmless warning on
24873f0c DS	38	* ALL_LIST_ELEMENTS_RO
	39	*/
	40	static struct list *work_queues = &_work_queues;
354d119a	41
	42	#define WORK_QUEUE_MIN_GRANULARITY 1
	43
d62a17ae	44	static struct work_queue_item work_queue_item_new(struct work_queue wq)
354d119a	45	{
d62a17ae	46	struct work_queue_item *item;
d62a17ae	47	assert(wq);
354d119a	48
d62a17ae	49	item = XCALLOC(MTYPE_WORK_QUEUE_ITEM, sizeof(struct work_queue_item));
	50
	51	return item;
354d119a	52	}
354d119a	53
d62a17ae	54	static void work_queue_item_free(struct work_queue_item *item)
354d119a	55	{
d62a17ae	56	XFREE(MTYPE_WORK_QUEUE_ITEM, item);
d62a17ae	57	return;
354d119a	58	}
	59
	60	/* create new work queue */
d62a17ae	61	struct work_queue work_queue_new(struct thread_master m,
d62a17ae	62	const char *queue_name)
354d119a	63	{
d62a17ae	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;
	73	SET_FLAG(new->flags, WQ_UNPLUGGED);
	74
	75	if ((new->items = list_new()) == NULL) {
	76	XFREE(MTYPE_WORK_QUEUE_NAME, new->name);
	77	XFREE(MTYPE_WORK_QUEUE, new);
	78
	79	return NULL;
	80	}
	81
	82	new->items->del = (void ()(void ))work_queue_item_free;
	83
	84	listnode_add(work_queues, new);
	85
	86	new->cycles.granularity = WORK_QUEUE_MIN_GRANULARITY;
	87
	88	/* Default values, can be overriden by caller */
	89	new->spec.hold = WORK_QUEUE_DEFAULT_HOLD;
	90	new->spec.yield = THREAD_YIELD_TIME_SLOT;
	91
	92	return new;
354d119a	93	}
354d119a	94
d62a17ae	95	void work_queue_free(struct work_queue *wq)
354d119a	96	{
d62a17ae	97	if (wq->thread != NULL)
	98	thread_cancel(wq->thread);
	99
	100	/* list_delete frees items via callback */
	101	list_delete(wq->items);
	102	listnode_delete(work_queues, wq);
	103
	104	XFREE(MTYPE_WORK_QUEUE_NAME, wq->name);
	105	XFREE(MTYPE_WORK_QUEUE, wq);
	106	return;
354d119a	107	}
354d119a	108
d62a17ae	109	bool work_queue_is_scheduled(struct work_queue *wq)
86582682	110	{
d62a17ae	111	return (wq->thread != NULL);
86582682 PJ	112	}
86582682 PJ	113
d62a17ae	114	static int work_queue_schedule(struct work_queue *wq, unsigned int delay)
269d74fd	115	{
d62a17ae	116	/* if appropriate, schedule work queue thread */
	117	if (CHECK_FLAG(wq->flags, WQ_UNPLUGGED) && (wq->thread == NULL)
	118	&& (listcount(wq->items) > 0)) {
	119	wq->thread = NULL;
	120	thread_add_timer_msec(wq->master, work_queue_run, wq, delay,
	121	&wq->thread);
	122	/* set thread yield time, if needed */
	123	if (wq->thread && wq->spec.yield != THREAD_YIELD_TIME_SLOT)
	124	thread_set_yield_time(wq->thread, wq->spec.yield);
	125	return 1;
	126	} else
	127	return 0;
269d74fd	128	}
d62a17ae	129
d62a17ae	130	void work_queue_add(struct work_queue wq, void data)
354d119a	131	{
d62a17ae	132	struct work_queue_item *item;
	133
	134	assert(wq);
	135
	136	if (!(item = work_queue_item_new(wq))) {
	137	zlog_err("%s: unable to get new queue item", __func__);
	138	return;
	139	}
	140
	141	item->data = data;
	142	listnode_add(wq->items, item);
	143
	144	work_queue_schedule(wq, wq->spec.hold);
	145
	146	return;
354d119a	147	}
354d119a	148
d62a17ae	149	static void work_queue_item_remove(struct work_queue wq, struct listnode ln)
354d119a	150	{
d62a17ae	151	struct work_queue_item *item = listgetdata(ln);
354d119a	152
d62a17ae	153	assert(item && item->data);
354d119a	154
d62a17ae	155	/* call private data deletion callback if needed */
	156	if (wq->spec.del_item_data)
	157	wq->spec.del_item_data(wq, item->data);
354d119a	158
d62a17ae	159	list_delete_node(wq->items, ln);
	160	work_queue_item_free(item);
	161
	162	return;
354d119a	163	}
354d119a	164
d62a17ae	165	static void work_queue_item_requeue(struct work_queue wq, struct listnode ln)
354d119a	166	{
d62a17ae	167	LISTNODE_DETACH(wq->items, ln);
d62a17ae	168	LISTNODE_ATTACH(wq->items, ln); /* attach to end of list */
354d119a	169	}
354d119a	170
49d41a26 DS	171	DEFUN (show_work_queues,
	172	show_work_queues_cmd,
	173	"show work-queues",
	174	SHOW_STR
	175	"Work Queue information\n")
354d119a	176	{
d62a17ae	177	struct listnode *node;
	178	struct work_queue *wq;
	179
	180	vty_out(vty, "%c %8s %5s %8s %8s %21s\n", ' ', "List", "(ms) ",
	181	"Q. Runs", "Yields", "Cycle Counts ");
	182	vty_out(vty, "%c %8s %5s %8s %8s %7s %6s %8s %6s %s\n", 'P', "Items",
	183	"Hold", "Total", "Total", "Best", "Gran.", "Total", "Avg.",
	184	"Name");
	185
	186	for (ALL_LIST_ELEMENTS_RO(work_queues, node, wq)) {
	187	vty_out(vty, "%c %8d %5d %8ld %8ld %7d %6d %8ld %6u %s\n",
	188	(CHECK_FLAG(wq->flags, WQ_UNPLUGGED) ? ' ' : 'P'),
	189	listcount(wq->items), wq->spec.hold, wq->runs,
	190	wq->yields, wq->cycles.best, wq->cycles.granularity,
	191	wq->cycles.total,
	192	(wq->runs) ? (unsigned int)(wq->cycles.total / wq->runs)
	193	: 0,
	194	wq->name);
	195	}
	196
	197	return CMD_SUCCESS;
354d119a	198	}
354d119a	199
d62a17ae	200	void workqueue_cmd_init(void)
0b84f294	201	{
d62a17ae	202	install_element(VIEW_NODE, &show_work_queues_cmd);
0b84f294 DL	203	}
0b84f294 DL	204
269d74fd	205	/* 'plug' a queue: Stop it from being scheduled,
	206	* ie: prevent the queue from draining.
	207	*/
d62a17ae	208	void work_queue_plug(struct work_queue *wq)
269d74fd	209	{
d62a17ae	210	if (wq->thread)
	211	thread_cancel(wq->thread);
	212
	213	wq->thread = NULL;
	214
	215	UNSET_FLAG(wq->flags, WQ_UNPLUGGED);
269d74fd	216	}
	217
	218	/* unplug queue, schedule it again, if appropriate
	219	* Ie: Allow the queue to be drained again
	220	*/
d62a17ae	221	void work_queue_unplug(struct work_queue *wq)
269d74fd	222	{
d62a17ae	223	SET_FLAG(wq->flags, WQ_UNPLUGGED);
269d74fd	224
d62a17ae	225	/* if thread isnt already waiting, add one */
d62a17ae	226	work_queue_schedule(wq, wq->spec.hold);
269d74fd	227	}
269d74fd	228
354d119a	229	/* timer thread to process a work queue
354d119a	230	* will reschedule itself if required,
d62a17ae	231	* otherwise work_queue_item_add
354d119a	232	*/
d62a17ae	233	int work_queue_run(struct thread *thread)
354d119a	234	{
d62a17ae	235	struct work_queue *wq;
	236	struct work_queue_item *item;
	237	wq_item_status ret;
	238	unsigned int cycles = 0;
	239	struct listnode node, nnode;
	240	char yielded = 0;
	241
	242	wq = THREAD_ARG(thread);
	243	wq->thread = NULL;
	244
	245	assert(wq && wq->items);
	246
	247	/* calculate cycle granularity:
	248	* list iteration == 1 run
	249	* listnode processing == 1 cycle
	250	* granularity == # cycles between checks whether we should yield.
	251	*
	252	* granularity should be > 0, and can increase slowly after each run to
	253	* provide some hysteris, but not past cycles.best or 2*cycles.
	254	*
	255	* Best: starts low, can only increase
	256	*
	257	* Granularity: starts at WORK_QUEUE_MIN_GRANULARITY, can be decreased
	258	* if we run to end of time slot, can increase otherwise
	259	* by a small factor.
	260	*
	261	* We could use just the average and save some work, however we want to
	262	* be
	263	* able to adjust quickly to CPU pressure. Average wont shift much if
	264	* daemon has been running a long time.
	265	*/
	266	if (wq->cycles.granularity == 0)
	267	wq->cycles.granularity = WORK_QUEUE_MIN_GRANULARITY;
	268
	269	for (ALL_LIST_ELEMENTS(wq->items, node, nnode, item)) {
	270	assert(item && item->data);
	271
	272	/* dont run items which are past their allowed retries */
	273	if (item->ran > wq->spec.max_retries) {
	274	/* run error handler, if any */
	275	if (wq->spec.errorfunc)
	276	wq->spec.errorfunc(wq, item->data);
	277	work_queue_item_remove(wq, node);
	278	continue;
	279	}
	280
	281	/* run and take care of items that want to be retried
	282	* immediately */
	283	do {
	284	ret = wq->spec.workfunc(wq, item->data);
	285	item->ran++;
	286	} while ((ret == WQ_RETRY_NOW)
	287	&& (item->ran < wq->spec.max_retries));
	288
	289	switch (ret) {
	290	case WQ_QUEUE_BLOCKED: {
	291	/* decrement item->ran again, cause this isn't an item
	292	* specific error, and fall through to WQ_RETRY_LATER
	293	*/
	294	item->ran--;
	295	}
	296	case WQ_RETRY_LATER: {
	297	goto stats;
	298	}
299	case WQ_REQUEUE: {
300	item->ran--;
301	work_queue_item_requeue(wq, node);
302	/* If a single node is being used with a meta-queue
303	* (e.g., zebra),
304	* update the next node as we don't want to exit the
305	* thread and
306	* reschedule it after every node. By definition,
307	* WQ_REQUEUE is
308	* meant to continue the processing; the yield logic
309	* will kick in
310	* to terminate the thread when time has exceeded.
311	*/
312	if (nnode == NULL)
313	nnode = node;
314	break;
315	}
316	case WQ_RETRY_NOW:
317	/* a RETRY_NOW that gets here has exceeded max_tries, same as
318	* ERROR */
319	case WQ_ERROR: {
320	if (wq->spec.errorfunc)
321	wq->spec.errorfunc(wq, item);
322	}
323	/* fallthru */
324	case WQ_SUCCESS:
325	default: {
326	work_queue_item_remove(wq, node);
327	break;
328	}
329	}
330
331	/* completed cycle */
332	cycles++;
333
334	/* test if we should yield */
335	if (!(cycles % wq->cycles.granularity)
336	&& thread_should_yield(thread)) {
337	yielded = 1;
338	goto stats;
339	}
354d119a	340	}
354d119a	341
	342	stats:
	343
3322055b	344	#define WQ_HYSTERESIS_FACTOR 4
354d119a	345
d62a17ae	346	/* we yielded, check whether granularity should be reduced */
	347	if (yielded && (cycles < wq->cycles.granularity)) {
	348	wq->cycles.granularity =
	349	((cycles > 0) ? cycles : WORK_QUEUE_MIN_GRANULARITY);
	350	}
	351	/* otherwise, should granularity increase? */
	352	else if (cycles >= (wq->cycles.granularity)) {
	353	if (cycles > wq->cycles.best)
	354	wq->cycles.best = cycles;
	355
	356	/* along with yielded check, provides hysteresis for granularity
	357	*/
	358	if (cycles > (wq->cycles.granularity * WQ_HYSTERESIS_FACTOR
	359	* WQ_HYSTERESIS_FACTOR))
	360	wq->cycles.granularity *=
	361	WQ_HYSTERESIS_FACTOR; /* quick ramp-up */
	362	else if (cycles
	363	> (wq->cycles.granularity * WQ_HYSTERESIS_FACTOR))
	364	wq->cycles.granularity += WQ_HYSTERESIS_FACTOR;
	365	}
354d119a	366	#undef WQ_HYSTERIS_FACTOR
d62a17ae	367
	368	wq->runs++;
	369	wq->cycles.total += cycles;
	370	if (yielded)
	371	wq->yields++;
354d119a	372
	373	#if 0
	374	printf ("%s: cycles %d, new: best %d, worst %d\n",
	375	__func__, cycles, wq->cycles.best, wq->cycles.granularity);
	376	#endif
d62a17ae	377
	378	/* Is the queue done yet? If it is, call the completion callback. */
	379	if (listcount(wq->items) > 0)
	380	work_queue_schedule(wq, 0);
	381	else if (wq->spec.completion_func)
	382	wq->spec.completion_func(wq);
	383
	384	return 0;
354d119a	385	}