[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;
}

static void work_queue_item_remove(struct work_queue *wq,
				   struct work_queue_item *item)
{
	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);

	work_queue_item_dequeue(wq, item);

	work_queue_item_free(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));

	new->name = XSTRDUP(MTYPE_WORK_QUEUE_NAME, queue_name);
	new->master = m;
	SET_FLAG(new->flags, WQ_UNPLUGGED);

	STAILQ_INIT(&new->items);

	listnode_add(work_queues, new);

	new->cycles.granularity = WORK_QUEUE_MIN_GRANULARITY;

	/* Default values, can be overridden by caller */
	new->spec.hold = WORK_QUEUE_DEFAULT_HOLD;
	new->spec.yield = THREAD_YIELD_TIME_SLOT;
	new->spec.retry = WORK_QUEUE_DEFAULT_RETRY;

	return new;
}

void work_queue_free_and_null(struct work_queue **wqp)
{
	struct work_queue *wq = *wqp;

	THREAD_OFF(wq->thread);

	while (!work_queue_empty(wq)) {
		struct work_queue_item *item = work_queue_last_item(wq);

		work_queue_item_remove(wq, item);
	}

	listnode_delete(work_queues, wq);

	XFREE(MTYPE_WORK_QUEUE_NAME, wq->name);
	XFREE(MTYPE_WORK_QUEUE, wq);

	*wqp = NULL;
}

bool work_queue_is_scheduled(struct work_queue *wq)
{
	return thread_is_scheduled(wq->thread);
}

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) &&
	    !thread_is_scheduled(wq->thread) && !work_queue_empty(wq)) {
		/* Schedule timer if there's a delay, otherwise just schedule
		 * as an 'event'
		 */
		if (delay > 0) {
			thread_add_timer_msec(wq->master, work_queue_run, wq,
					      delay, &wq->thread);
			thread_ignore_late_timer(wq->thread);
		} else
			thread_add_event(wq->master, work_queue_run, wq, 0,
					 &wq->thread);

		/* set thread yield time, if needed */
		if (thread_is_scheduled(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);

	item = work_queue_item_new(wq);

	item->data = data;
	work_queue_item_enqueue(wq, item);

	work_queue_schedule(wq, wq->spec.hold);

	return;
}

static void work_queue_item_requeue(struct work_queue *wq,
				    struct work_queue_item *item)
{
	work_queue_item_dequeue(wq, item);

	/* attach to end of list */
	work_queue_item_enqueue(wq, item);
}

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'),
			work_queue_item_count(wq), 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)
{
	THREAD_OFF(wq->thread);

	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
 */
void work_queue_run(struct thread *thread)
{
	struct work_queue *wq;
	struct work_queue_item *item, *titem;
	wq_item_status ret = WQ_SUCCESS;
	unsigned int cycles = 0;
	char yielded = 0;

	wq = THREAD_ARG(thread);

	assert(wq);

	/* 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;

	STAILQ_FOREACH_SAFE (item, &wq->items, wq, titem) {
		assert(item->data);

		/* dont run items which are past their allowed retries */
		if (item->ran > wq->spec.max_retries) {
			work_queue_item_remove(wq, item);
			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, item);
			/* 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 (titem == NULL)
				titem = item;
			break;
		}
		case WQ_RETRY_NOW:
		/* a RETRY_NOW that gets here has exceeded max_tries, same as
		 * ERROR */
		/* fallthru */
		case WQ_SUCCESS:
		default: {
			work_queue_item_remove(wq, item);
			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++;

	/* Is the queue done yet? If it is, call the completion callback. */
	if (!work_queue_empty(wq)) {
		if (ret == WQ_RETRY_LATER ||
		    ret == WQ_QUEUE_BLOCKED)
			work_queue_schedule(wq, wq->spec.retry);
		else
			work_queue_schedule(wq, 0);

	} else if (wq->spec.completion_func)
		wq->spec.completion_func(wq);
}
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
bf8d3d6a DL	31	DEFINE_MTYPE(LIB, WORK_QUEUE, "Work queue");
	32	DEFINE_MTYPE_STATIC(LIB, WORK_QUEUE_ITEM, "Work queue item");
	33	DEFINE_MTYPE_STATIC(LIB, WORK_QUEUE_NAME, "Work queue name string");
4a1ab8e4	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	}
354d119a	59
da7f979a DS	60	static void work_queue_item_remove(struct work_queue *wq,
	61	struct work_queue_item *item)
	62	{
	63	assert(item && item->data);
	64
	65	/* call private data deletion callback if needed */
	66	if (wq->spec.del_item_data)
	67	wq->spec.del_item_data(wq, item->data);
	68
	69	work_queue_item_dequeue(wq, item);
	70
	71	work_queue_item_free(item);
	72
	73	return;
	74	}
	75
354d119a	76	/* create new work queue */
d62a17ae	77	struct work_queue work_queue_new(struct thread_master m,
d62a17ae	78	const char *queue_name)
354d119a	79	{
d62a17ae	80	struct work_queue *new;
	81
	82	new = XCALLOC(MTYPE_WORK_QUEUE, sizeof(struct work_queue));
	83
d62a17ae	84	new->name = XSTRDUP(MTYPE_WORK_QUEUE_NAME, queue_name);
	85	new->master = m;
	86	SET_FLAG(new->flags, WQ_UNPLUGGED);
	87
f104f6c1	88	STAILQ_INIT(&new->items);
d62a17ae	89
	90	listnode_add(work_queues, new);
	91
	92	new->cycles.granularity = WORK_QUEUE_MIN_GRANULARITY;
	93
5418f988	94	/* Default values, can be overridden by caller */
d62a17ae	95	new->spec.hold = WORK_QUEUE_DEFAULT_HOLD;
d62a17ae	96	new->spec.yield = THREAD_YIELD_TIME_SLOT;
5418f988	97	new->spec.retry = WORK_QUEUE_DEFAULT_RETRY;
d62a17ae	98
d62a17ae	99	return new;
354d119a	100	}
354d119a	101
6b097e33	102	void work_queue_free_and_null(struct work_queue **wqp)
354d119a	103	{
6b097e33 MS	104	struct work_queue wq = wqp;
6b097e33 MS	105
d1c27668	106	THREAD_OFF(wq->thread);
d62a17ae	107
da7f979a DS	108	while (!work_queue_empty(wq)) {
	109	struct work_queue_item *item = work_queue_last_item(wq);
	110
	111	work_queue_item_remove(wq, item);
	112	}
	113
d62a17ae	114	listnode_delete(work_queues, wq);
	115
	116	XFREE(MTYPE_WORK_QUEUE_NAME, wq->name);
	117	XFREE(MTYPE_WORK_QUEUE, wq);
354d119a	118
6b097e33	119	*wqp = NULL;
e208c8f9 DS	120	}
e208c8f9 DS	121
d62a17ae	122	bool work_queue_is_scheduled(struct work_queue *wq)
86582682	123	{
d1c27668	124	return thread_is_scheduled(wq->thread);
86582682 PJ	125	}
86582682 PJ	126
d62a17ae	127	static int work_queue_schedule(struct work_queue *wq, unsigned int delay)
269d74fd	128	{
d62a17ae	129	/* if appropriate, schedule work queue thread */
d1c27668 DS	130	if (CHECK_FLAG(wq->flags, WQ_UNPLUGGED) &&
d1c27668 DS	131	!thread_is_scheduled(wq->thread) && !work_queue_empty(wq)) {
5418f988 MS	132	/* Schedule timer if there's a delay, otherwise just schedule
	133	* as an 'event'
	134	*/
e8b3a2f7	135	if (delay > 0) {
5418f988 MS	136	thread_add_timer_msec(wq->master, work_queue_run, wq,
5418f988 MS	137	delay, &wq->thread);
e8b3a2f7 DS	138	thread_ignore_late_timer(wq->thread);
e8b3a2f7 DS	139	} else
5418f988 MS	140	thread_add_event(wq->master, work_queue_run, wq, 0,
	141	&wq->thread);
	142
d62a17ae	143	/* set thread yield time, if needed */
d1c27668 DS	144	if (thread_is_scheduled(wq->thread) &&
d1c27668 DS	145	wq->spec.yield != THREAD_YIELD_TIME_SLOT)
d62a17ae	146	thread_set_yield_time(wq->thread, wq->spec.yield);
	147	return 1;
	148	} else
	149	return 0;
269d74fd	150	}
d62a17ae	151
d62a17ae	152	void work_queue_add(struct work_queue wq, void data)
354d119a	153	{
d62a17ae	154	struct work_queue_item *item;
	155
	156	assert(wq);
	157
0ce1ca80	158	item = work_queue_item_new(wq);
d62a17ae	159
d62a17ae	160	item->data = data;
f104f6c1	161	work_queue_item_enqueue(wq, item);
d62a17ae	162
	163	work_queue_schedule(wq, wq->spec.hold);
	164
	165	return;
354d119a	166	}
354d119a	167
996c9314 LB	168	static void work_queue_item_requeue(struct work_queue *wq,
996c9314 LB	169	struct work_queue_item *item)
354d119a	170	{
f104f6c1 JB	171	work_queue_item_dequeue(wq, item);
	172
	173	/* attach to end of list */
	174	work_queue_item_enqueue(wq, item);
354d119a	175	}
354d119a	176
49d41a26 DS	177	DEFUN (show_work_queues,
	178	show_work_queues_cmd,
	179	"show work-queues",
	180	SHOW_STR
	181	"Work Queue information\n")
354d119a	182	{
d62a17ae	183	struct listnode *node;
	184	struct work_queue *wq;
	185
	186	vty_out(vty, "%c %8s %5s %8s %8s %21s\n", ' ', "List", "(ms) ",
	187	"Q. Runs", "Yields", "Cycle Counts ");
	188	vty_out(vty, "%c %8s %5s %8s %8s %7s %6s %8s %6s %s\n", 'P', "Items",
	189	"Hold", "Total", "Total", "Best", "Gran.", "Total", "Avg.",
	190	"Name");
	191
	192	for (ALL_LIST_ELEMENTS_RO(work_queues, node, wq)) {
	193	vty_out(vty, "%c %8d %5d %8ld %8ld %7d %6d %8ld %6u %s\n",
	194	(CHECK_FLAG(wq->flags, WQ_UNPLUGGED) ? ' ' : 'P'),
f104f6c1	195	work_queue_item_count(wq), wq->spec.hold, wq->runs,
d62a17ae	196	wq->yields, wq->cycles.best, wq->cycles.granularity,
	197	wq->cycles.total,
	198	(wq->runs) ? (unsigned int)(wq->cycles.total / wq->runs)
	199	: 0,
	200	wq->name);
	201	}
	202
	203	return CMD_SUCCESS;
354d119a	204	}
354d119a	205
d62a17ae	206	void workqueue_cmd_init(void)
0b84f294	207	{
d62a17ae	208	install_element(VIEW_NODE, &show_work_queues_cmd);
0b84f294 DL	209	}
0b84f294 DL	210
269d74fd	211	/* 'plug' a queue: Stop it from being scheduled,
	212	* ie: prevent the queue from draining.
	213	*/
d62a17ae	214	void work_queue_plug(struct work_queue *wq)
269d74fd	215	{
d1c27668	216	THREAD_OFF(wq->thread);
d62a17ae	217
d62a17ae	218	UNSET_FLAG(wq->flags, WQ_UNPLUGGED);
269d74fd	219	}
	220
	221	/* unplug queue, schedule it again, if appropriate
	222	* Ie: Allow the queue to be drained again
	223	*/
d62a17ae	224	void work_queue_unplug(struct work_queue *wq)
269d74fd	225	{
d62a17ae	226	SET_FLAG(wq->flags, WQ_UNPLUGGED);
269d74fd	227
d62a17ae	228	/* if thread isnt already waiting, add one */
d62a17ae	229	work_queue_schedule(wq, wq->spec.hold);
269d74fd	230	}
269d74fd	231
354d119a	232	/* timer thread to process a work queue
354d119a	233	* will reschedule itself if required,
d62a17ae	234	* otherwise work_queue_item_add
354d119a	235	*/
cc9f21da	236	void work_queue_run(struct thread *thread)
354d119a	237	{
d62a17ae	238	struct work_queue *wq;
f104f6c1	239	struct work_queue_item item, titem;
5418f988	240	wq_item_status ret = WQ_SUCCESS;
d62a17ae	241	unsigned int cycles = 0;
d62a17ae	242	char yielded = 0;
	243
	244	wq = THREAD_ARG(thread);
d62a17ae	245
f104f6c1	246	assert(wq);
d62a17ae	247
	248	/* calculate cycle granularity:
	249	* list iteration == 1 run
	250	* listnode processing == 1 cycle
	251	* granularity == # cycles between checks whether we should yield.
	252	*
	253	* granularity should be > 0, and can increase slowly after each run to
	254	* provide some hysteris, but not past cycles.best or 2*cycles.
	255	*
	256	* Best: starts low, can only increase
	257	*
	258	* Granularity: starts at WORK_QUEUE_MIN_GRANULARITY, can be decreased
	259	* if we run to end of time slot, can increase otherwise
	260	* by a small factor.
	261	*
	262	* We could use just the average and save some work, however we want to
	263	* be
	264	* able to adjust quickly to CPU pressure. Average wont shift much if
	265	* daemon has been running a long time.
	266	*/
	267	if (wq->cycles.granularity == 0)
	268	wq->cycles.granularity = WORK_QUEUE_MIN_GRANULARITY;
	269
a2addae8	270	STAILQ_FOREACH_SAFE (item, &wq->items, wq, titem) {
1383ff9c	271	assert(item->data);
d62a17ae	272
	273	/* dont run items which are past their allowed retries */
	274	if (item->ran > wq->spec.max_retries) {
f104f6c1	275	work_queue_item_remove(wq, item);
d62a17ae	276	continue;
	277	}
	278
	279	/* run and take care of items that want to be retried
	280	* immediately */
	281	do {
	282	ret = wq->spec.workfunc(wq, item->data);
	283	item->ran++;
	284	} while ((ret == WQ_RETRY_NOW)
	285	&& (item->ran < wq->spec.max_retries));
	286
	287	switch (ret) {
	288	case WQ_QUEUE_BLOCKED: {
	289	/* decrement item->ran again, cause this isn't an item
	290	* specific error, and fall through to WQ_RETRY_LATER
	291	*/
	292	item->ran--;
	293	}
	294	case WQ_RETRY_LATER: {
	295	goto stats;
	296	}
	297	case WQ_REQUEUE: {
	298	item->ran--;
f104f6c1	299	work_queue_item_requeue(wq, item);
d62a17ae	300	/* If a single node is being used with a meta-queue
	301	* (e.g., zebra),
	302	* update the next node as we don't want to exit the
	303	* thread and
	304	* reschedule it after every node. By definition,
	305	* WQ_REQUEUE is
	306	* meant to continue the processing; the yield logic
	307	* will kick in
	308	* to terminate the thread when time has exceeded.
	309	*/
f104f6c1 JB	310	if (titem == NULL)
f104f6c1 JB	311	titem = item;
d62a17ae	312	break;
	313	}
	314	case WQ_RETRY_NOW:
	315	/* a RETRY_NOW that gets here has exceeded max_tries, same as
	316	* ERROR */
d62a17ae	317	/* fallthru */
	318	case WQ_SUCCESS:
	319	default: {
f104f6c1	320	work_queue_item_remove(wq, item);
d62a17ae	321	break;
	322	}
	323	}
	324
	325	/* completed cycle */
	326	cycles++;
	327
	328	/* test if we should yield */
	329	if (!(cycles % wq->cycles.granularity)
	330	&& thread_should_yield(thread)) {
	331	yielded = 1;
	332	goto stats;
	333	}
354d119a	334	}
354d119a	335
	336	stats:
	337
3322055b	338	#define WQ_HYSTERESIS_FACTOR 4
354d119a	339
d62a17ae	340	/* we yielded, check whether granularity should be reduced */
	341	if (yielded && (cycles < wq->cycles.granularity)) {
	342	wq->cycles.granularity =
	343	((cycles > 0) ? cycles : WORK_QUEUE_MIN_GRANULARITY);
	344	}
	345	/* otherwise, should granularity increase? */
	346	else if (cycles >= (wq->cycles.granularity)) {
	347	if (cycles > wq->cycles.best)
	348	wq->cycles.best = cycles;
	349
	350	/* along with yielded check, provides hysteresis for granularity
	351	*/
	352	if (cycles > (wq->cycles.granularity * WQ_HYSTERESIS_FACTOR
	353	* WQ_HYSTERESIS_FACTOR))
	354	wq->cycles.granularity *=
	355	WQ_HYSTERESIS_FACTOR; /* quick ramp-up */
	356	else if (cycles
	357	> (wq->cycles.granularity * WQ_HYSTERESIS_FACTOR))
	358	wq->cycles.granularity += WQ_HYSTERESIS_FACTOR;
	359	}
354d119a	360	#undef WQ_HYSTERIS_FACTOR
d62a17ae	361
	362	wq->runs++;
	363	wq->cycles.total += cycles;
	364	if (yielded)
	365	wq->yields++;
354d119a	366
d62a17ae	367	/* Is the queue done yet? If it is, call the completion callback. */
5418f988 MS	368	if (!work_queue_empty(wq)) {
	369	if (ret == WQ_RETRY_LATER \|\|
	370	ret == WQ_QUEUE_BLOCKED)
	371	work_queue_schedule(wq, wq->spec.retry);
	372	else
	373	work_queue_schedule(wq, 0);
	374
	375	} else if (wq->spec.completion_func)
d62a17ae	376	wq->spec.completion_func(wq);
354d119a	377	}