blob: 535007d5f0b523b13bffac7e314710f58d9ce7ef [file] [log] [blame]
Eric Dumazet76e3cc12012-05-10 07:51:25 +00001/*
2 * Codel - The Controlled-Delay Active Queue Management algorithm
3 *
4 * Copyright (C) 2011-2012 Kathleen Nichols <nichols@pollere.com>
5 * Copyright (C) 2011-2012 Van Jacobson <van@pollere.net>
6 *
7 * Implemented on linux by :
8 * Copyright (C) 2012 Michael D. Taht <dave.taht@bufferbloat.net>
Eric Dumazet80ba92f2015-05-08 15:05:12 -07009 * Copyright (C) 2012,2015 Eric Dumazet <edumazet@google.com>
Eric Dumazet76e3cc12012-05-10 07:51:25 +000010 *
11 * Redistribution and use in source and binary forms, with or without
12 * modification, are permitted provided that the following conditions
13 * are met:
14 * 1. Redistributions of source code must retain the above copyright
15 * notice, this list of conditions, and the following disclaimer,
16 * without modification.
17 * 2. Redistributions in binary form must reproduce the above copyright
18 * notice, this list of conditions and the following disclaimer in the
19 * documentation and/or other materials provided with the distribution.
20 * 3. The names of the authors may not be used to endorse or promote products
21 * derived from this software without specific prior written permission.
22 *
23 * Alternatively, provided that this notice is retained in full, this
24 * software may be distributed under the terms of the GNU General
25 * Public License ("GPL") version 2, in which case the provisions of the
26 * GPL apply INSTEAD OF those given above.
27 *
28 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
29 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
30 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
31 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
32 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
33 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
34 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
35 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
36 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
37 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
38 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH
39 * DAMAGE.
40 *
41 */
42
43#include <linux/module.h>
44#include <linux/slab.h>
45#include <linux/types.h>
46#include <linux/kernel.h>
47#include <linux/errno.h>
48#include <linux/skbuff.h>
Geert Uytterhoevence5b4b92012-05-14 09:47:05 +000049#include <linux/prefetch.h>
Eric Dumazet76e3cc12012-05-10 07:51:25 +000050#include <net/pkt_sched.h>
51#include <net/codel.h>
52
53
54#define DEFAULT_CODEL_LIMIT 1000
55
56struct codel_sched_data {
57 struct codel_params params;
58 struct codel_vars vars;
59 struct codel_stats stats;
60 u32 drop_overlimit;
61};
62
63/* This is the specific function called from codel_dequeue()
64 * to dequeue a packet from queue. Note: backlog is handled in
65 * codel, we dont need to reduce it here.
66 */
67static struct sk_buff *dequeue(struct codel_vars *vars, struct Qdisc *sch)
68{
69 struct sk_buff *skb = __skb_dequeue(&sch->q);
70
71 prefetch(&skb->end); /* we'll need skb_shinfo() */
72 return skb;
73}
74
75static struct sk_buff *codel_qdisc_dequeue(struct Qdisc *sch)
76{
77 struct codel_sched_data *q = qdisc_priv(sch);
78 struct sk_buff *skb;
79
Eric Dumazet865ec552012-05-16 04:39:09 +000080 skb = codel_dequeue(sch, &q->params, &q->vars, &q->stats, dequeue);
81
Eric Dumazet76e3cc12012-05-10 07:51:25 +000082 /* We cant call qdisc_tree_decrease_qlen() if our qlen is 0,
83 * or HTB crashes. Defer it for next round.
84 */
85 if (q->stats.drop_count && sch->q.qlen) {
86 qdisc_tree_decrease_qlen(sch, q->stats.drop_count);
87 q->stats.drop_count = 0;
88 }
89 if (skb)
90 qdisc_bstats_update(sch, skb);
91 return skb;
92}
93
94static int codel_qdisc_enqueue(struct sk_buff *skb, struct Qdisc *sch)
95{
96 struct codel_sched_data *q;
97
98 if (likely(qdisc_qlen(sch) < sch->limit)) {
99 codel_set_enqueue_time(skb);
100 return qdisc_enqueue_tail(skb, sch);
101 }
102 q = qdisc_priv(sch);
103 q->drop_overlimit++;
104 return qdisc_drop(skb, sch);
105}
106
107static const struct nla_policy codel_policy[TCA_CODEL_MAX + 1] = {
108 [TCA_CODEL_TARGET] = { .type = NLA_U32 },
109 [TCA_CODEL_LIMIT] = { .type = NLA_U32 },
110 [TCA_CODEL_INTERVAL] = { .type = NLA_U32 },
111 [TCA_CODEL_ECN] = { .type = NLA_U32 },
Eric Dumazet80ba92f2015-05-08 15:05:12 -0700112 [TCA_CODEL_CE_THRESHOLD]= { .type = NLA_U32 },
Eric Dumazet76e3cc12012-05-10 07:51:25 +0000113};
114
115static int codel_change(struct Qdisc *sch, struct nlattr *opt)
116{
117 struct codel_sched_data *q = qdisc_priv(sch);
118 struct nlattr *tb[TCA_CODEL_MAX + 1];
119 unsigned int qlen;
120 int err;
121
122 if (!opt)
123 return -EINVAL;
124
125 err = nla_parse_nested(tb, TCA_CODEL_MAX, opt, codel_policy);
126 if (err < 0)
127 return err;
128
129 sch_tree_lock(sch);
130
131 if (tb[TCA_CODEL_TARGET]) {
132 u32 target = nla_get_u32(tb[TCA_CODEL_TARGET]);
133
134 q->params.target = ((u64)target * NSEC_PER_USEC) >> CODEL_SHIFT;
135 }
136
Eric Dumazet80ba92f2015-05-08 15:05:12 -0700137 if (tb[TCA_CODEL_CE_THRESHOLD]) {
138 u64 val = nla_get_u32(tb[TCA_CODEL_CE_THRESHOLD]);
139
140 q->params.ce_threshold = (val * NSEC_PER_USEC) >> CODEL_SHIFT;
141 }
142
Eric Dumazet76e3cc12012-05-10 07:51:25 +0000143 if (tb[TCA_CODEL_INTERVAL]) {
144 u32 interval = nla_get_u32(tb[TCA_CODEL_INTERVAL]);
145
146 q->params.interval = ((u64)interval * NSEC_PER_USEC) >> CODEL_SHIFT;
147 }
148
149 if (tb[TCA_CODEL_LIMIT])
150 sch->limit = nla_get_u32(tb[TCA_CODEL_LIMIT]);
151
152 if (tb[TCA_CODEL_ECN])
153 q->params.ecn = !!nla_get_u32(tb[TCA_CODEL_ECN]);
154
155 qlen = sch->q.qlen;
156 while (sch->q.qlen > sch->limit) {
157 struct sk_buff *skb = __skb_dequeue(&sch->q);
158
John Fastabend25331d62014-09-28 11:53:29 -0700159 qdisc_qstats_backlog_dec(sch, skb);
Eric Dumazet76e3cc12012-05-10 07:51:25 +0000160 qdisc_drop(skb, sch);
161 }
162 qdisc_tree_decrease_qlen(sch, qlen - sch->q.qlen);
163
164 sch_tree_unlock(sch);
165 return 0;
166}
167
168static int codel_init(struct Qdisc *sch, struct nlattr *opt)
169{
170 struct codel_sched_data *q = qdisc_priv(sch);
171
172 sch->limit = DEFAULT_CODEL_LIMIT;
173
Eric Dumazeta5d28092015-04-30 09:40:40 -0700174 codel_params_init(&q->params, sch);
Eric Dumazet76e3cc12012-05-10 07:51:25 +0000175 codel_vars_init(&q->vars);
176 codel_stats_init(&q->stats);
177
178 if (opt) {
179 int err = codel_change(sch, opt);
180
181 if (err)
182 return err;
183 }
184
185 if (sch->limit >= 1)
186 sch->flags |= TCQ_F_CAN_BYPASS;
187 else
188 sch->flags &= ~TCQ_F_CAN_BYPASS;
189
190 return 0;
191}
192
193static int codel_dump(struct Qdisc *sch, struct sk_buff *skb)
194{
195 struct codel_sched_data *q = qdisc_priv(sch);
196 struct nlattr *opts;
197
198 opts = nla_nest_start(skb, TCA_OPTIONS);
199 if (opts == NULL)
200 goto nla_put_failure;
201
202 if (nla_put_u32(skb, TCA_CODEL_TARGET,
203 codel_time_to_us(q->params.target)) ||
204 nla_put_u32(skb, TCA_CODEL_LIMIT,
205 sch->limit) ||
206 nla_put_u32(skb, TCA_CODEL_INTERVAL,
207 codel_time_to_us(q->params.interval)) ||
208 nla_put_u32(skb, TCA_CODEL_ECN,
209 q->params.ecn))
210 goto nla_put_failure;
Eric Dumazet80ba92f2015-05-08 15:05:12 -0700211 if (q->params.ce_threshold != CODEL_DISABLED_THRESHOLD &&
212 nla_put_u32(skb, TCA_CODEL_CE_THRESHOLD,
213 codel_time_to_us(q->params.ce_threshold)))
214 goto nla_put_failure;
Eric Dumazet76e3cc12012-05-10 07:51:25 +0000215 return nla_nest_end(skb, opts);
216
217nla_put_failure:
218 nla_nest_cancel(skb, opts);
219 return -1;
220}
221
222static int codel_dump_stats(struct Qdisc *sch, struct gnet_dump *d)
223{
224 const struct codel_sched_data *q = qdisc_priv(sch);
225 struct tc_codel_xstats st = {
226 .maxpacket = q->stats.maxpacket,
227 .count = q->vars.count,
228 .lastcount = q->vars.lastcount,
229 .drop_overlimit = q->drop_overlimit,
230 .ldelay = codel_time_to_us(q->vars.ldelay),
231 .dropping = q->vars.dropping,
232 .ecn_mark = q->stats.ecn_mark,
Eric Dumazet80ba92f2015-05-08 15:05:12 -0700233 .ce_mark = q->stats.ce_mark,
Eric Dumazet76e3cc12012-05-10 07:51:25 +0000234 };
235
236 if (q->vars.dropping) {
237 codel_tdiff_t delta = q->vars.drop_next - codel_get_time();
238
239 if (delta >= 0)
240 st.drop_next = codel_time_to_us(delta);
241 else
242 st.drop_next = -codel_time_to_us(-delta);
243 }
244
245 return gnet_stats_copy_app(d, &st, sizeof(st));
246}
247
248static void codel_reset(struct Qdisc *sch)
249{
250 struct codel_sched_data *q = qdisc_priv(sch);
251
252 qdisc_reset_queue(sch);
253 codel_vars_init(&q->vars);
254}
255
256static struct Qdisc_ops codel_qdisc_ops __read_mostly = {
257 .id = "codel",
258 .priv_size = sizeof(struct codel_sched_data),
259
260 .enqueue = codel_qdisc_enqueue,
261 .dequeue = codel_qdisc_dequeue,
262 .peek = qdisc_peek_dequeued,
263 .init = codel_init,
264 .reset = codel_reset,
265 .change = codel_change,
266 .dump = codel_dump,
267 .dump_stats = codel_dump_stats,
268 .owner = THIS_MODULE,
269};
270
271static int __init codel_module_init(void)
272{
273 return register_qdisc(&codel_qdisc_ops);
274}
275
276static void __exit codel_module_exit(void)
277{
278 unregister_qdisc(&codel_qdisc_ops);
279}
280
281module_init(codel_module_init)
282module_exit(codel_module_exit)
283
284MODULE_DESCRIPTION("Controlled Delay queue discipline");
285MODULE_AUTHOR("Dave Taht");
286MODULE_AUTHOR("Eric Dumazet");
287MODULE_LICENSE("Dual BSD/GPL");