2 * Quagga Work Queue Support.
4 * Copyright (C) 2005 Sun Microsystems, Inc.
6 * This file is part of GNU Zebra.
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
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.
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
26 #include "workqueue.h"
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")
35 /* master list of work_queues */
36 static struct list _work_queues
;
37 /* pointer primarily to avoid an otherwise harmless warning on
38 * ALL_LIST_ELEMENTS_RO
40 static struct list
*work_queues
= &_work_queues
;
42 #define WORK_QUEUE_MIN_GRANULARITY 1
44 static struct work_queue_item
*work_queue_item_new(struct work_queue
*wq
)
46 struct work_queue_item
*item
;
49 item
= XCALLOC(MTYPE_WORK_QUEUE_ITEM
, sizeof(struct work_queue_item
));
54 static void work_queue_item_free(struct work_queue_item
*item
)
56 XFREE(MTYPE_WORK_QUEUE_ITEM
, item
);
60 /* create new work queue */
61 struct work_queue
*work_queue_new(struct thread_master
*m
,
62 const char *queue_name
)
64 struct work_queue
*new;
66 new = XCALLOC(MTYPE_WORK_QUEUE
, sizeof(struct work_queue
));
71 new->name
= XSTRDUP(MTYPE_WORK_QUEUE_NAME
, queue_name
);
73 SET_FLAG(new->flags
, WQ_UNPLUGGED
);
75 STAILQ_INIT(&new->items
);
77 listnode_add(work_queues
, new);
79 new->cycles
.granularity
= WORK_QUEUE_MIN_GRANULARITY
;
81 /* Default values, can be overriden by caller */
82 new->spec
.hold
= WORK_QUEUE_DEFAULT_HOLD
;
83 new->spec
.yield
= THREAD_YIELD_TIME_SLOT
;
88 void work_queue_free(struct work_queue
*wq
)
90 if (wq
->thread
!= NULL
)
91 thread_cancel(wq
->thread
);
93 listnode_delete(work_queues
, wq
);
95 XFREE(MTYPE_WORK_QUEUE_NAME
, wq
->name
);
96 XFREE(MTYPE_WORK_QUEUE
, wq
);
100 bool work_queue_is_scheduled(struct work_queue
*wq
)
102 return (wq
->thread
!= NULL
);
105 static int work_queue_schedule(struct work_queue
*wq
, unsigned int delay
)
107 /* if appropriate, schedule work queue thread */
108 if (CHECK_FLAG(wq
->flags
, WQ_UNPLUGGED
) && (wq
->thread
== NULL
) &&
109 !work_queue_empty(wq
)) {
111 thread_add_timer_msec(wq
->master
, work_queue_run
, wq
, delay
,
113 /* set thread yield time, if needed */
114 if (wq
->thread
&& wq
->spec
.yield
!= THREAD_YIELD_TIME_SLOT
)
115 thread_set_yield_time(wq
->thread
, wq
->spec
.yield
);
121 void work_queue_add(struct work_queue
*wq
, void *data
)
123 struct work_queue_item
*item
;
127 if (!(item
= work_queue_item_new(wq
))) {
128 zlog_err("%s: unable to get new queue item", __func__
);
133 work_queue_item_enqueue(wq
, item
);
135 work_queue_schedule(wq
, wq
->spec
.hold
);
140 static void work_queue_item_remove(struct work_queue
*wq
,
141 struct work_queue_item
*item
)
143 assert(item
&& item
->data
);
145 /* call private data deletion callback if needed */
146 if (wq
->spec
.del_item_data
)
147 wq
->spec
.del_item_data(wq
, item
->data
);
149 work_queue_item_dequeue(wq
, item
);
151 work_queue_item_free(item
);
156 static void work_queue_item_requeue(struct work_queue
*wq
, struct work_queue_item
*item
)
158 work_queue_item_dequeue(wq
, item
);
160 /* attach to end of list */
161 work_queue_item_enqueue(wq
, item
);
164 DEFUN (show_work_queues
,
165 show_work_queues_cmd
,
168 "Work Queue information\n")
170 struct listnode
*node
;
171 struct work_queue
*wq
;
173 vty_out(vty
, "%c %8s %5s %8s %8s %21s\n", ' ', "List", "(ms) ",
174 "Q. Runs", "Yields", "Cycle Counts ");
175 vty_out(vty
, "%c %8s %5s %8s %8s %7s %6s %8s %6s %s\n", 'P', "Items",
176 "Hold", "Total", "Total", "Best", "Gran.", "Total", "Avg.",
179 for (ALL_LIST_ELEMENTS_RO(work_queues
, node
, wq
)) {
180 vty_out(vty
, "%c %8d %5d %8ld %8ld %7d %6d %8ld %6u %s\n",
181 (CHECK_FLAG(wq
->flags
, WQ_UNPLUGGED
) ? ' ' : 'P'),
182 work_queue_item_count(wq
), wq
->spec
.hold
, wq
->runs
,
183 wq
->yields
, wq
->cycles
.best
, wq
->cycles
.granularity
,
185 (wq
->runs
) ? (unsigned int)(wq
->cycles
.total
/ wq
->runs
)
193 void workqueue_cmd_init(void)
195 install_element(VIEW_NODE
, &show_work_queues_cmd
);
198 /* 'plug' a queue: Stop it from being scheduled,
199 * ie: prevent the queue from draining.
201 void work_queue_plug(struct work_queue
*wq
)
204 thread_cancel(wq
->thread
);
208 UNSET_FLAG(wq
->flags
, WQ_UNPLUGGED
);
211 /* unplug queue, schedule it again, if appropriate
212 * Ie: Allow the queue to be drained again
214 void work_queue_unplug(struct work_queue
*wq
)
216 SET_FLAG(wq
->flags
, WQ_UNPLUGGED
);
218 /* if thread isnt already waiting, add one */
219 work_queue_schedule(wq
, wq
->spec
.hold
);
222 /* timer thread to process a work queue
223 * will reschedule itself if required,
224 * otherwise work_queue_item_add
226 int work_queue_run(struct thread
*thread
)
228 struct work_queue
*wq
;
229 struct work_queue_item
*item
, *titem
;
231 unsigned int cycles
= 0;
234 wq
= THREAD_ARG(thread
);
239 /* calculate cycle granularity:
240 * list iteration == 1 run
241 * listnode processing == 1 cycle
242 * granularity == # cycles between checks whether we should yield.
244 * granularity should be > 0, and can increase slowly after each run to
245 * provide some hysteris, but not past cycles.best or 2*cycles.
247 * Best: starts low, can only increase
249 * Granularity: starts at WORK_QUEUE_MIN_GRANULARITY, can be decreased
250 * if we run to end of time slot, can increase otherwise
253 * We could use just the average and save some work, however we want to
255 * able to adjust quickly to CPU pressure. Average wont shift much if
256 * daemon has been running a long time.
258 if (wq
->cycles
.granularity
== 0)
259 wq
->cycles
.granularity
= WORK_QUEUE_MIN_GRANULARITY
;
261 STAILQ_FOREACH_SAFE(item
, &wq
->items
, wq
, titem
) {
262 assert(item
&& item
->data
);
264 /* dont run items which are past their allowed retries */
265 if (item
->ran
> wq
->spec
.max_retries
) {
266 /* run error handler, if any */
267 if (wq
->spec
.errorfunc
)
268 wq
->spec
.errorfunc(wq
, item
->data
);
269 work_queue_item_remove(wq
, item
);
273 /* run and take care of items that want to be retried
276 ret
= wq
->spec
.workfunc(wq
, item
->data
);
278 } while ((ret
== WQ_RETRY_NOW
)
279 && (item
->ran
< wq
->spec
.max_retries
));
282 case WQ_QUEUE_BLOCKED
: {
283 /* decrement item->ran again, cause this isn't an item
284 * specific error, and fall through to WQ_RETRY_LATER
288 case WQ_RETRY_LATER
: {
293 work_queue_item_requeue(wq
, item
);
294 /* If a single node is being used with a meta-queue
296 * update the next node as we don't want to exit the
298 * reschedule it after every node. By definition,
300 * meant to continue the processing; the yield logic
302 * to terminate the thread when time has exceeded.
309 /* a RETRY_NOW that gets here has exceeded max_tries, same as
312 if (wq
->spec
.errorfunc
)
313 wq
->spec
.errorfunc(wq
, item
);
318 work_queue_item_remove(wq
, item
);
323 /* completed cycle */
326 /* test if we should yield */
327 if (!(cycles
% wq
->cycles
.granularity
)
328 && thread_should_yield(thread
)) {
336 #define WQ_HYSTERESIS_FACTOR 4
338 /* we yielded, check whether granularity should be reduced */
339 if (yielded
&& (cycles
< wq
->cycles
.granularity
)) {
340 wq
->cycles
.granularity
=
341 ((cycles
> 0) ? cycles
: WORK_QUEUE_MIN_GRANULARITY
);
343 /* otherwise, should granularity increase? */
344 else if (cycles
>= (wq
->cycles
.granularity
)) {
345 if (cycles
> wq
->cycles
.best
)
346 wq
->cycles
.best
= cycles
;
348 /* along with yielded check, provides hysteresis for granularity
350 if (cycles
> (wq
->cycles
.granularity
* WQ_HYSTERESIS_FACTOR
351 * WQ_HYSTERESIS_FACTOR
))
352 wq
->cycles
.granularity
*=
353 WQ_HYSTERESIS_FACTOR
; /* quick ramp-up */
355 > (wq
->cycles
.granularity
* WQ_HYSTERESIS_FACTOR
))
356 wq
->cycles
.granularity
+= WQ_HYSTERESIS_FACTOR
;
358 #undef WQ_HYSTERIS_FACTOR
361 wq
->cycles
.total
+= cycles
;
366 printf ("%s: cycles %d, new: best %d, worst %d\n",
367 __func__
, cycles
, wq
->cycles
.best
, wq
->cycles
.granularity
);
370 /* Is the queue done yet? If it is, call the completion callback. */
371 if (!work_queue_empty(wq
))
372 work_queue_schedule(wq
, 0);
373 else if (wq
->spec
.completion_func
)
374 wq
->spec
.completion_func(wq
);