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1 | /* Copyright (C) 2013 Cisco Systems, Inc, 2013. |
2 | * | |
3 | * This program is free software; you can redistribute it and/or | |
4 | * modify it under the terms of the GNU General Public License | |
5 | * as published by the Free Software Foundation; either version 2 | |
6 | * of the License. | |
7 | * | |
8 | * This program is distributed in the hope that it will be useful, | |
9 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
10 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
11 | * GNU General Public License for more details. | |
12 | * | |
13 | * Author: Vijay Subramanian <vijaynsu@cisco.com> | |
14 | * Author: Mythili Prabhu <mysuryan@cisco.com> | |
15 | * | |
16 | * ECN support is added by Naeem Khademi <naeemk@ifi.uio.no> | |
17 | * University of Oslo, Norway. | |
18 | */ | |
19 | ||
20 | #include <linux/module.h> | |
21 | #include <linux/slab.h> | |
22 | #include <linux/types.h> | |
23 | #include <linux/kernel.h> | |
24 | #include <linux/errno.h> | |
25 | #include <linux/skbuff.h> | |
26 | #include <net/pkt_sched.h> | |
27 | #include <net/inet_ecn.h> | |
28 | ||
29 | #define QUEUE_THRESHOLD 10000 | |
30 | #define DQCOUNT_INVALID -1 | |
31 | #define MAX_PROB 0xffffffff | |
32 | #define PIE_SCALE 8 | |
33 | ||
34 | /* parameters used */ | |
35 | struct pie_params { | |
36 | psched_time_t target; /* user specified target delay in pschedtime */ | |
37 | u32 tupdate; /* timer frequency (in jiffies) */ | |
38 | u32 limit; /* number of packets that can be enqueued */ | |
39 | u32 alpha; /* alpha and beta are between -4 and 4 */ | |
40 | u32 beta; /* and are used for shift relative to 1 */ | |
41 | bool ecn; /* true if ecn is enabled */ | |
42 | bool bytemode; /* to scale drop early prob based on pkt size */ | |
43 | }; | |
44 | ||
45 | /* variables used */ | |
46 | struct pie_vars { | |
47 | u32 prob; /* probability but scaled by u32 limit. */ | |
48 | psched_time_t burst_time; | |
49 | psched_time_t qdelay; | |
50 | psched_time_t qdelay_old; | |
51 | u64 dq_count; /* measured in bytes */ | |
52 | psched_time_t dq_tstamp; /* drain rate */ | |
53 | u32 avg_dq_rate; /* bytes per pschedtime tick,scaled */ | |
54 | u32 qlen_old; /* in bytes */ | |
55 | }; | |
56 | ||
57 | /* statistics gathering */ | |
58 | struct pie_stats { | |
59 | u32 packets_in; /* total number of packets enqueued */ | |
60 | u32 dropped; /* packets dropped due to pie_action */ | |
61 | u32 overlimit; /* dropped due to lack of space in queue */ | |
62 | u32 maxq; /* maximum queue size */ | |
63 | u32 ecn_mark; /* packets marked with ECN */ | |
64 | }; | |
65 | ||
66 | /* private data for the Qdisc */ | |
67 | struct pie_sched_data { | |
68 | struct pie_params params; | |
69 | struct pie_vars vars; | |
70 | struct pie_stats stats; | |
71 | struct timer_list adapt_timer; | |
72 | }; | |
73 | ||
74 | static void pie_params_init(struct pie_params *params) | |
75 | { | |
76 | params->alpha = 2; | |
77 | params->beta = 20; | |
78 | params->tupdate = usecs_to_jiffies(30 * USEC_PER_MSEC); /* 30 ms */ | |
79 | params->limit = 1000; /* default of 1000 packets */ | |
80 | params->target = PSCHED_NS2TICKS(20 * NSEC_PER_MSEC); /* 20 ms */ | |
81 | params->ecn = false; | |
82 | params->bytemode = false; | |
83 | } | |
84 | ||
85 | static void pie_vars_init(struct pie_vars *vars) | |
86 | { | |
87 | vars->dq_count = DQCOUNT_INVALID; | |
88 | vars->avg_dq_rate = 0; | |
89 | /* default of 100 ms in pschedtime */ | |
90 | vars->burst_time = PSCHED_NS2TICKS(100 * NSEC_PER_MSEC); | |
91 | } | |
92 | ||
93 | static bool drop_early(struct Qdisc *sch, u32 packet_size) | |
94 | { | |
95 | struct pie_sched_data *q = qdisc_priv(sch); | |
96 | u32 rnd; | |
97 | u32 local_prob = q->vars.prob; | |
98 | u32 mtu = psched_mtu(qdisc_dev(sch)); | |
99 | ||
100 | /* If there is still burst allowance left skip random early drop */ | |
101 | if (q->vars.burst_time > 0) | |
102 | return false; | |
103 | ||
104 | /* If current delay is less than half of target, and | |
105 | * if drop prob is low already, disable early_drop | |
106 | */ | |
107 | if ((q->vars.qdelay < q->params.target / 2) | |
108 | && (q->vars.prob < MAX_PROB / 5)) | |
109 | return false; | |
110 | ||
111 | /* If we have fewer than 2 mtu-sized packets, disable drop_early, | |
112 | * similar to min_th in RED | |
113 | */ | |
114 | if (sch->qstats.backlog < 2 * mtu) | |
115 | return false; | |
116 | ||
117 | /* If bytemode is turned on, use packet size to compute new | |
118 | * probablity. Smaller packets will have lower drop prob in this case | |
119 | */ | |
120 | if (q->params.bytemode && packet_size <= mtu) | |
121 | local_prob = (local_prob / mtu) * packet_size; | |
122 | else | |
123 | local_prob = q->vars.prob; | |
124 | ||
125 | rnd = net_random(); | |
126 | if (rnd < local_prob) | |
127 | return true; | |
128 | ||
129 | return false; | |
130 | } | |
131 | ||
132 | static int pie_qdisc_enqueue(struct sk_buff *skb, struct Qdisc *sch) | |
133 | { | |
134 | struct pie_sched_data *q = qdisc_priv(sch); | |
135 | bool enqueue = false; | |
136 | ||
137 | if (unlikely(qdisc_qlen(sch) >= sch->limit)) { | |
138 | q->stats.overlimit++; | |
139 | goto out; | |
140 | } | |
141 | ||
142 | if (!drop_early(sch, skb->len)) { | |
143 | enqueue = true; | |
144 | } else if (q->params.ecn && (q->vars.prob <= MAX_PROB / 10) && | |
145 | INET_ECN_set_ce(skb)) { | |
146 | /* If packet is ecn capable, mark it if drop probability | |
147 | * is lower than 10%, else drop it. | |
148 | */ | |
149 | q->stats.ecn_mark++; | |
150 | enqueue = true; | |
151 | } | |
152 | ||
153 | /* we can enqueue the packet */ | |
154 | if (enqueue) { | |
155 | q->stats.packets_in++; | |
156 | if (qdisc_qlen(sch) > q->stats.maxq) | |
157 | q->stats.maxq = qdisc_qlen(sch); | |
158 | ||
159 | return qdisc_enqueue_tail(skb, sch); | |
160 | } | |
161 | ||
162 | out: | |
163 | q->stats.dropped++; | |
164 | return qdisc_drop(skb, sch); | |
165 | } | |
166 | ||
167 | static const struct nla_policy pie_policy[TCA_PIE_MAX + 1] = { | |
168 | [TCA_PIE_TARGET] = {.type = NLA_U32}, | |
169 | [TCA_PIE_LIMIT] = {.type = NLA_U32}, | |
170 | [TCA_PIE_TUPDATE] = {.type = NLA_U32}, | |
171 | [TCA_PIE_ALPHA] = {.type = NLA_U32}, | |
172 | [TCA_PIE_BETA] = {.type = NLA_U32}, | |
173 | [TCA_PIE_ECN] = {.type = NLA_U32}, | |
174 | [TCA_PIE_BYTEMODE] = {.type = NLA_U32}, | |
175 | }; | |
176 | ||
177 | static int pie_change(struct Qdisc *sch, struct nlattr *opt) | |
178 | { | |
179 | struct pie_sched_data *q = qdisc_priv(sch); | |
180 | struct nlattr *tb[TCA_PIE_MAX + 1]; | |
181 | unsigned int qlen; | |
182 | int err; | |
183 | ||
184 | if (!opt) | |
185 | return -EINVAL; | |
186 | ||
187 | err = nla_parse_nested(tb, TCA_PIE_MAX, opt, pie_policy); | |
188 | if (err < 0) | |
189 | return err; | |
190 | ||
191 | sch_tree_lock(sch); | |
192 | ||
193 | /* convert from microseconds to pschedtime */ | |
194 | if (tb[TCA_PIE_TARGET]) { | |
195 | /* target is in us */ | |
196 | u32 target = nla_get_u32(tb[TCA_PIE_TARGET]); | |
197 | ||
198 | /* convert to pschedtime */ | |
199 | q->params.target = PSCHED_NS2TICKS((u64)target * NSEC_PER_USEC); | |
200 | } | |
201 | ||
202 | /* tupdate is in jiffies */ | |
203 | if (tb[TCA_PIE_TUPDATE]) | |
204 | q->params.tupdate = usecs_to_jiffies(nla_get_u32(tb[TCA_PIE_TUPDATE])); | |
205 | ||
206 | if (tb[TCA_PIE_LIMIT]) { | |
207 | u32 limit = nla_get_u32(tb[TCA_PIE_LIMIT]); | |
208 | ||
209 | q->params.limit = limit; | |
210 | sch->limit = limit; | |
211 | } | |
212 | ||
213 | if (tb[TCA_PIE_ALPHA]) | |
214 | q->params.alpha = nla_get_u32(tb[TCA_PIE_ALPHA]); | |
215 | ||
216 | if (tb[TCA_PIE_BETA]) | |
217 | q->params.beta = nla_get_u32(tb[TCA_PIE_BETA]); | |
218 | ||
219 | if (tb[TCA_PIE_ECN]) | |
220 | q->params.ecn = nla_get_u32(tb[TCA_PIE_ECN]); | |
221 | ||
222 | if (tb[TCA_PIE_BYTEMODE]) | |
223 | q->params.bytemode = nla_get_u32(tb[TCA_PIE_BYTEMODE]); | |
224 | ||
225 | /* Drop excess packets if new limit is lower */ | |
226 | qlen = sch->q.qlen; | |
227 | while (sch->q.qlen > sch->limit) { | |
228 | struct sk_buff *skb = __skb_dequeue(&sch->q); | |
229 | ||
230 | sch->qstats.backlog -= qdisc_pkt_len(skb); | |
231 | qdisc_drop(skb, sch); | |
232 | } | |
233 | qdisc_tree_decrease_qlen(sch, qlen - sch->q.qlen); | |
234 | ||
235 | sch_tree_unlock(sch); | |
236 | return 0; | |
237 | } | |
238 | ||
239 | static void pie_process_dequeue(struct Qdisc *sch, struct sk_buff *skb) | |
240 | { | |
241 | ||
242 | struct pie_sched_data *q = qdisc_priv(sch); | |
243 | int qlen = sch->qstats.backlog; /* current queue size in bytes */ | |
244 | ||
245 | /* If current queue is about 10 packets or more and dq_count is unset | |
246 | * we have enough packets to calculate the drain rate. Save | |
247 | * current time as dq_tstamp and start measurement cycle. | |
248 | */ | |
249 | if (qlen >= QUEUE_THRESHOLD && q->vars.dq_count == DQCOUNT_INVALID) { | |
250 | q->vars.dq_tstamp = psched_get_time(); | |
251 | q->vars.dq_count = 0; | |
252 | } | |
253 | ||
254 | /* Calculate the average drain rate from this value. If queue length | |
255 | * has receded to a small value viz., <= QUEUE_THRESHOLD bytes,reset | |
256 | * the dq_count to -1 as we don't have enough packets to calculate the | |
257 | * drain rate anymore The following if block is entered only when we | |
258 | * have a substantial queue built up (QUEUE_THRESHOLD bytes or more) | |
259 | * and we calculate the drain rate for the threshold here. dq_count is | |
260 | * in bytes, time difference in psched_time, hence rate is in | |
261 | * bytes/psched_time. | |
262 | */ | |
263 | if (q->vars.dq_count != DQCOUNT_INVALID) { | |
264 | q->vars.dq_count += skb->len; | |
265 | ||
266 | if (q->vars.dq_count >= QUEUE_THRESHOLD) { | |
267 | psched_time_t now = psched_get_time(); | |
268 | u32 dtime = now - q->vars.dq_tstamp; | |
269 | u32 count = q->vars.dq_count << PIE_SCALE; | |
270 | ||
271 | if (dtime == 0) | |
272 | return; | |
273 | ||
274 | count = count / dtime; | |
275 | ||
276 | if (q->vars.avg_dq_rate == 0) | |
277 | q->vars.avg_dq_rate = count; | |
278 | else | |
279 | q->vars.avg_dq_rate = | |
280 | (q->vars.avg_dq_rate - | |
281 | (q->vars.avg_dq_rate >> 3)) + (count >> 3); | |
282 | ||
283 | /* If the queue has receded below the threshold, we hold | |
284 | * on to the last drain rate calculated, else we reset | |
285 | * dq_count to 0 to re-enter the if block when the next | |
286 | * packet is dequeued | |
287 | */ | |
288 | if (qlen < QUEUE_THRESHOLD) | |
289 | q->vars.dq_count = DQCOUNT_INVALID; | |
290 | else { | |
291 | q->vars.dq_count = 0; | |
292 | q->vars.dq_tstamp = psched_get_time(); | |
293 | } | |
294 | ||
295 | if (q->vars.burst_time > 0) { | |
296 | if (q->vars.burst_time > dtime) | |
297 | q->vars.burst_time -= dtime; | |
298 | else | |
299 | q->vars.burst_time = 0; | |
300 | } | |
301 | } | |
302 | } | |
303 | } | |
304 | ||
305 | static void calculate_probability(struct Qdisc *sch) | |
306 | { | |
307 | struct pie_sched_data *q = qdisc_priv(sch); | |
308 | u32 qlen = sch->qstats.backlog; /* queue size in bytes */ | |
309 | psched_time_t qdelay = 0; /* in pschedtime */ | |
310 | psched_time_t qdelay_old = q->vars.qdelay; /* in pschedtime */ | |
311 | s32 delta = 0; /* determines the change in probability */ | |
312 | u32 oldprob; | |
313 | u32 alpha, beta; | |
314 | bool update_prob = true; | |
315 | ||
316 | q->vars.qdelay_old = q->vars.qdelay; | |
317 | ||
318 | if (q->vars.avg_dq_rate > 0) | |
319 | qdelay = (qlen << PIE_SCALE) / q->vars.avg_dq_rate; | |
320 | else | |
321 | qdelay = 0; | |
322 | ||
323 | /* If qdelay is zero and qlen is not, it means qlen is very small, less | |
324 | * than dequeue_rate, so we do not update probabilty in this round | |
325 | */ | |
326 | if (qdelay == 0 && qlen != 0) | |
327 | update_prob = false; | |
328 | ||
329 | /* Add ranges for alpha and beta, more aggressive for high dropping | |
330 | * mode and gentle steps for light dropping mode | |
331 | * In light dropping mode, take gentle steps; in medium dropping mode, | |
332 | * take medium steps; in high dropping mode, take big steps. | |
333 | */ | |
334 | if (q->vars.prob < MAX_PROB / 100) { | |
335 | alpha = | |
336 | (q->params.alpha * (MAX_PROB / PSCHED_TICKS_PER_SEC)) >> 7; | |
337 | beta = | |
338 | (q->params.beta * (MAX_PROB / PSCHED_TICKS_PER_SEC)) >> 7; | |
339 | } else if (q->vars.prob < MAX_PROB / 10) { | |
340 | alpha = | |
341 | (q->params.alpha * (MAX_PROB / PSCHED_TICKS_PER_SEC)) >> 5; | |
342 | beta = | |
343 | (q->params.beta * (MAX_PROB / PSCHED_TICKS_PER_SEC)) >> 5; | |
344 | } else { | |
345 | alpha = | |
346 | (q->params.alpha * (MAX_PROB / PSCHED_TICKS_PER_SEC)) >> 4; | |
347 | beta = | |
348 | (q->params.beta * (MAX_PROB / PSCHED_TICKS_PER_SEC)) >> 4; | |
349 | } | |
350 | ||
351 | /* alpha and beta should be between 0 and 32, in multiples of 1/16 */ | |
352 | delta += alpha * ((qdelay - q->params.target)); | |
353 | delta += beta * ((qdelay - qdelay_old)); | |
354 | ||
355 | oldprob = q->vars.prob; | |
356 | ||
357 | /* to ensure we increase probability in steps of no more than 2% */ | |
358 | if (delta > (s32) (MAX_PROB / (100 / 2)) && | |
359 | q->vars.prob >= MAX_PROB / 10) | |
360 | delta = (MAX_PROB / 100) * 2; | |
361 | ||
362 | /* Non-linear drop: | |
363 | * Tune drop probability to increase quickly for high delays(>= 250ms) | |
364 | * 250ms is derived through experiments and provides error protection | |
365 | */ | |
366 | ||
367 | if (qdelay > (PSCHED_NS2TICKS(250 * NSEC_PER_MSEC))) | |
368 | delta += MAX_PROB / (100 / 2); | |
369 | ||
370 | q->vars.prob += delta; | |
371 | ||
372 | if (delta > 0) { | |
373 | /* prevent overflow */ | |
374 | if (q->vars.prob < oldprob) { | |
375 | q->vars.prob = MAX_PROB; | |
376 | /* Prevent normalization error. If probability is at | |
377 | * maximum value already, we normalize it here, and | |
378 | * skip the check to do a non-linear drop in the next | |
379 | * section. | |
380 | */ | |
381 | update_prob = false; | |
382 | } | |
383 | } else { | |
384 | /* prevent underflow */ | |
385 | if (q->vars.prob > oldprob) | |
386 | q->vars.prob = 0; | |
387 | } | |
388 | ||
389 | /* Non-linear drop in probability: Reduce drop probability quickly if | |
390 | * delay is 0 for 2 consecutive Tupdate periods. | |
391 | */ | |
392 | ||
393 | if ((qdelay == 0) && (qdelay_old == 0) && update_prob) | |
394 | q->vars.prob = (q->vars.prob * 98) / 100; | |
395 | ||
396 | q->vars.qdelay = qdelay; | |
397 | q->vars.qlen_old = qlen; | |
398 | ||
399 | /* We restart the measurement cycle if the following conditions are met | |
400 | * 1. If the delay has been low for 2 consecutive Tupdate periods | |
401 | * 2. Calculated drop probability is zero | |
402 | * 3. We have atleast one estimate for the avg_dq_rate ie., | |
403 | * is a non-zero value | |
404 | */ | |
405 | if ((q->vars.qdelay < q->params.target / 2) && | |
406 | (q->vars.qdelay_old < q->params.target / 2) && | |
407 | (q->vars.prob == 0) && | |
408 | (q->vars.avg_dq_rate > 0)) | |
409 | pie_vars_init(&q->vars); | |
410 | } | |
411 | ||
412 | static void pie_timer(unsigned long arg) | |
413 | { | |
414 | struct Qdisc *sch = (struct Qdisc *)arg; | |
415 | struct pie_sched_data *q = qdisc_priv(sch); | |
416 | spinlock_t *root_lock = qdisc_lock(qdisc_root_sleeping(sch)); | |
417 | ||
418 | spin_lock(root_lock); | |
419 | calculate_probability(sch); | |
420 | ||
421 | /* reset the timer to fire after 'tupdate'. tupdate is in jiffies. */ | |
422 | if (q->params.tupdate) | |
423 | mod_timer(&q->adapt_timer, jiffies + q->params.tupdate); | |
424 | spin_unlock(root_lock); | |
425 | ||
426 | } | |
427 | ||
428 | static int pie_init(struct Qdisc *sch, struct nlattr *opt) | |
429 | { | |
430 | struct pie_sched_data *q = qdisc_priv(sch); | |
431 | ||
432 | pie_params_init(&q->params); | |
433 | pie_vars_init(&q->vars); | |
434 | sch->limit = q->params.limit; | |
435 | ||
436 | setup_timer(&q->adapt_timer, pie_timer, (unsigned long)sch); | |
437 | mod_timer(&q->adapt_timer, jiffies + HZ / 2); | |
438 | ||
439 | if (opt) { | |
440 | int err = pie_change(sch, opt); | |
441 | ||
442 | if (err) | |
443 | return err; | |
444 | } | |
445 | ||
446 | return 0; | |
447 | } | |
448 | ||
449 | static int pie_dump(struct Qdisc *sch, struct sk_buff *skb) | |
450 | { | |
451 | struct pie_sched_data *q = qdisc_priv(sch); | |
452 | struct nlattr *opts; | |
453 | ||
454 | opts = nla_nest_start(skb, TCA_OPTIONS); | |
455 | if (opts == NULL) | |
456 | goto nla_put_failure; | |
457 | ||
458 | /* convert target from pschedtime to us */ | |
459 | if (nla_put_u32(skb, TCA_PIE_TARGET, | |
460 | ((u32) PSCHED_TICKS2NS(q->params.target)) / | |
461 | NSEC_PER_USEC) || | |
462 | nla_put_u32(skb, TCA_PIE_LIMIT, sch->limit) || | |
463 | nla_put_u32(skb, TCA_PIE_TUPDATE, jiffies_to_usecs(q->params.tupdate)) || | |
464 | nla_put_u32(skb, TCA_PIE_ALPHA, q->params.alpha) || | |
465 | nla_put_u32(skb, TCA_PIE_BETA, q->params.beta) || | |
466 | nla_put_u32(skb, TCA_PIE_ECN, q->params.ecn) || | |
467 | nla_put_u32(skb, TCA_PIE_BYTEMODE, q->params.bytemode)) | |
468 | goto nla_put_failure; | |
469 | ||
470 | return nla_nest_end(skb, opts); | |
471 | ||
472 | nla_put_failure: | |
473 | nla_nest_cancel(skb, opts); | |
474 | return -1; | |
475 | ||
476 | } | |
477 | ||
478 | static int pie_dump_stats(struct Qdisc *sch, struct gnet_dump *d) | |
479 | { | |
480 | struct pie_sched_data *q = qdisc_priv(sch); | |
481 | struct tc_pie_xstats st = { | |
482 | .prob = q->vars.prob, | |
483 | .delay = ((u32) PSCHED_TICKS2NS(q->vars.qdelay)) / | |
484 | NSEC_PER_USEC, | |
485 | /* unscale and return dq_rate in bytes per sec */ | |
486 | .avg_dq_rate = q->vars.avg_dq_rate * | |
487 | (PSCHED_TICKS_PER_SEC) >> PIE_SCALE, | |
488 | .packets_in = q->stats.packets_in, | |
489 | .overlimit = q->stats.overlimit, | |
490 | .maxq = q->stats.maxq, | |
491 | .dropped = q->stats.dropped, | |
492 | .ecn_mark = q->stats.ecn_mark, | |
493 | }; | |
494 | ||
495 | return gnet_stats_copy_app(d, &st, sizeof(st)); | |
496 | } | |
497 | ||
498 | static struct sk_buff *pie_qdisc_dequeue(struct Qdisc *sch) | |
499 | { | |
500 | struct sk_buff *skb; | |
501 | skb = __qdisc_dequeue_head(sch, &sch->q); | |
502 | ||
503 | if (!skb) | |
504 | return NULL; | |
505 | ||
506 | pie_process_dequeue(sch, skb); | |
507 | return skb; | |
508 | } | |
509 | ||
510 | static void pie_reset(struct Qdisc *sch) | |
511 | { | |
512 | struct pie_sched_data *q = qdisc_priv(sch); | |
513 | qdisc_reset_queue(sch); | |
514 | pie_vars_init(&q->vars); | |
515 | } | |
516 | ||
517 | static void pie_destroy(struct Qdisc *sch) | |
518 | { | |
519 | struct pie_sched_data *q = qdisc_priv(sch); | |
520 | q->params.tupdate = 0; | |
521 | del_timer_sync(&q->adapt_timer); | |
522 | } | |
523 | ||
524 | static struct Qdisc_ops pie_qdisc_ops __read_mostly = { | |
525 | .id = "pie", | |
526 | .priv_size = sizeof(struct pie_sched_data), | |
527 | .enqueue = pie_qdisc_enqueue, | |
528 | .dequeue = pie_qdisc_dequeue, | |
529 | .peek = qdisc_peek_dequeued, | |
530 | .init = pie_init, | |
531 | .destroy = pie_destroy, | |
532 | .reset = pie_reset, | |
533 | .change = pie_change, | |
534 | .dump = pie_dump, | |
535 | .dump_stats = pie_dump_stats, | |
536 | .owner = THIS_MODULE, | |
537 | }; | |
538 | ||
539 | static int __init pie_module_init(void) | |
540 | { | |
541 | return register_qdisc(&pie_qdisc_ops); | |
542 | } | |
543 | ||
544 | static void __exit pie_module_exit(void) | |
545 | { | |
546 | unregister_qdisc(&pie_qdisc_ops); | |
547 | } | |
548 | ||
549 | module_init(pie_module_init); | |
550 | module_exit(pie_module_exit); | |
551 | ||
552 | MODULE_DESCRIPTION("Proportional Integral controller Enhanced (PIE) scheduler"); | |
553 | MODULE_AUTHOR("Vijay Subramanian"); | |
554 | MODULE_AUTHOR("Mythili Prabhu"); | |
555 | MODULE_LICENSE("GPL"); |