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1da177e4 LT |
1 | /* |
2 | * net/sched/gen_estimator.c Simple rate estimator. | |
3 | * | |
4 | * This program is free software; you can redistribute it and/or | |
5 | * modify it under the terms of the GNU General Public License | |
6 | * as published by the Free Software Foundation; either version | |
7 | * 2 of the License, or (at your option) any later version. | |
8 | * | |
9 | * Authors: Alexey Kuznetsov, <kuznet@ms2.inr.ac.ru> | |
10 | * | |
11 | * Changes: | |
12 | * Jamal Hadi Salim - moved it to net/core and reshulfed | |
13 | * names to make it usable in general net subsystem. | |
14 | */ | |
15 | ||
16 | #include <asm/uaccess.h> | |
17 | #include <asm/system.h> | |
1977f032 | 18 | #include <linux/bitops.h> |
1da177e4 LT |
19 | #include <linux/module.h> |
20 | #include <linux/types.h> | |
21 | #include <linux/kernel.h> | |
22 | #include <linux/jiffies.h> | |
23 | #include <linux/string.h> | |
24 | #include <linux/mm.h> | |
25 | #include <linux/socket.h> | |
26 | #include <linux/sockios.h> | |
27 | #include <linux/in.h> | |
28 | #include <linux/errno.h> | |
29 | #include <linux/interrupt.h> | |
30 | #include <linux/netdevice.h> | |
31 | #include <linux/skbuff.h> | |
32 | #include <linux/rtnetlink.h> | |
33 | #include <linux/init.h> | |
34 | #include <net/sock.h> | |
35 | #include <net/gen_stats.h> | |
36 | ||
37 | /* | |
38 | This code is NOT intended to be used for statistics collection, | |
39 | its purpose is to provide a base for statistical multiplexing | |
40 | for controlled load service. | |
41 | If you need only statistics, run a user level daemon which | |
42 | periodically reads byte counters. | |
43 | ||
44 | Unfortunately, rate estimation is not a very easy task. | |
45 | F.e. I did not find a simple way to estimate the current peak rate | |
46 | and even failed to formulate the problem 8)8) | |
47 | ||
48 | So I preferred not to built an estimator into the scheduler, | |
49 | but run this task separately. | |
50 | Ideally, it should be kernel thread(s), but for now it runs | |
51 | from timers, which puts apparent top bounds on the number of rated | |
52 | flows, has minimal overhead on small, but is enough | |
53 | to handle controlled load service, sets of aggregates. | |
54 | ||
55 | We measure rate over A=(1<<interval) seconds and evaluate EWMA: | |
56 | ||
57 | avrate = avrate*(1-W) + rate*W | |
58 | ||
59 | where W is chosen as negative power of 2: W = 2^(-ewma_log) | |
60 | ||
61 | The resulting time constant is: | |
62 | ||
63 | T = A/(-ln(1-W)) | |
64 | ||
65 | ||
66 | NOTES. | |
67 | ||
68 | * The stored value for avbps is scaled by 2^5, so that maximal | |
69 | rate is ~1Gbit, avpps is scaled by 2^10. | |
70 | ||
71 | * Minimal interval is HZ/4=250msec (it is the greatest common divisor | |
72 | for HZ=100 and HZ=1024 8)), maximal interval | |
73 | is (HZ*2^EST_MAX_INTERVAL)/4 = 8sec. Shorter intervals | |
74 | are too expensive, longer ones can be implemented | |
75 | at user level painlessly. | |
76 | */ | |
77 | ||
78 | #define EST_MAX_INTERVAL 5 | |
79 | ||
80 | struct gen_estimator | |
81 | { | |
0929c2dd | 82 | struct list_head list; |
1da177e4 LT |
83 | struct gnet_stats_basic *bstats; |
84 | struct gnet_stats_rate_est *rate_est; | |
85 | spinlock_t *stats_lock; | |
1da177e4 LT |
86 | int ewma_log; |
87 | u64 last_bytes; | |
88 | u32 last_packets; | |
89 | u32 avpps; | |
90 | u32 avbps; | |
0929c2dd | 91 | struct rcu_head e_rcu; |
1da177e4 LT |
92 | }; |
93 | ||
94 | struct gen_estimator_head | |
95 | { | |
96 | struct timer_list timer; | |
0929c2dd | 97 | struct list_head list; |
1da177e4 LT |
98 | }; |
99 | ||
100 | static struct gen_estimator_head elist[EST_MAX_INTERVAL+1]; | |
101 | ||
0929c2dd | 102 | /* Protects against NULL dereference */ |
1da177e4 LT |
103 | static DEFINE_RWLOCK(est_lock); |
104 | ||
105 | static void est_timer(unsigned long arg) | |
106 | { | |
107 | int idx = (int)arg; | |
108 | struct gen_estimator *e; | |
109 | ||
0929c2dd RZ |
110 | rcu_read_lock(); |
111 | list_for_each_entry_rcu(e, &elist[idx].list, list) { | |
1da177e4 LT |
112 | u64 nbytes; |
113 | u32 npackets; | |
114 | u32 rate; | |
115 | ||
116 | spin_lock(e->stats_lock); | |
0929c2dd RZ |
117 | read_lock(&est_lock); |
118 | if (e->bstats == NULL) | |
119 | goto skip; | |
120 | ||
1da177e4 LT |
121 | nbytes = e->bstats->bytes; |
122 | npackets = e->bstats->packets; | |
123 | rate = (nbytes - e->last_bytes)<<(7 - idx); | |
124 | e->last_bytes = nbytes; | |
125 | e->avbps += ((long)rate - (long)e->avbps) >> e->ewma_log; | |
126 | e->rate_est->bps = (e->avbps+0xF)>>5; | |
127 | ||
128 | rate = (npackets - e->last_packets)<<(12 - idx); | |
129 | e->last_packets = npackets; | |
130 | e->avpps += ((long)rate - (long)e->avpps) >> e->ewma_log; | |
131 | e->rate_est->pps = (e->avpps+0x1FF)>>10; | |
0929c2dd RZ |
132 | skip: |
133 | read_unlock(&est_lock); | |
1da177e4 LT |
134 | spin_unlock(e->stats_lock); |
135 | } | |
136 | ||
0929c2dd | 137 | if (!list_empty(&elist[idx].list)) |
789675e2 | 138 | mod_timer(&elist[idx].timer, jiffies + ((HZ/4) << idx)); |
0929c2dd | 139 | rcu_read_unlock(); |
1da177e4 LT |
140 | } |
141 | ||
142 | /** | |
143 | * gen_new_estimator - create a new rate estimator | |
144 | * @bstats: basic statistics | |
145 | * @rate_est: rate estimator statistics | |
146 | * @stats_lock: statistics lock | |
147 | * @opt: rate estimator configuration TLV | |
148 | * | |
149 | * Creates a new rate estimator with &bstats as source and &rate_est | |
150 | * as destination. A new timer with the interval specified in the | |
151 | * configuration TLV is created. Upon each interval, the latest statistics | |
152 | * will be read from &bstats and the estimated rate will be stored in | |
153 | * &rate_est with the statistics lock grabed during this period. | |
4ec93edb | 154 | * |
1da177e4 | 155 | * Returns 0 on success or a negative error code. |
0929c2dd RZ |
156 | * |
157 | * NOTE: Called under rtnl_mutex | |
1da177e4 LT |
158 | */ |
159 | int gen_new_estimator(struct gnet_stats_basic *bstats, | |
0929c2dd RZ |
160 | struct gnet_stats_rate_est *rate_est, |
161 | spinlock_t *stats_lock, | |
1e90474c | 162 | struct nlattr *opt) |
1da177e4 LT |
163 | { |
164 | struct gen_estimator *est; | |
1e90474c | 165 | struct gnet_estimator *parm = nla_data(opt); |
0929c2dd | 166 | int idx; |
1da177e4 | 167 | |
1e90474c | 168 | if (nla_len(opt) < sizeof(*parm)) |
1da177e4 LT |
169 | return -EINVAL; |
170 | ||
171 | if (parm->interval < -2 || parm->interval > 3) | |
172 | return -EINVAL; | |
173 | ||
77d04bd9 | 174 | est = kzalloc(sizeof(*est), GFP_KERNEL); |
1da177e4 LT |
175 | if (est == NULL) |
176 | return -ENOBUFS; | |
177 | ||
0929c2dd | 178 | idx = parm->interval + 2; |
1da177e4 LT |
179 | est->bstats = bstats; |
180 | est->rate_est = rate_est; | |
181 | est->stats_lock = stats_lock; | |
182 | est->ewma_log = parm->ewma_log; | |
183 | est->last_bytes = bstats->bytes; | |
184 | est->avbps = rate_est->bps<<5; | |
185 | est->last_packets = bstats->packets; | |
186 | est->avpps = rate_est->pps<<10; | |
187 | ||
0929c2dd RZ |
188 | if (!elist[idx].timer.function) { |
189 | INIT_LIST_HEAD(&elist[idx].list); | |
190 | setup_timer(&elist[idx].timer, est_timer, idx); | |
1da177e4 | 191 | } |
0929c2dd RZ |
192 | |
193 | if (list_empty(&elist[idx].list)) | |
789675e2 | 194 | mod_timer(&elist[idx].timer, jiffies + ((HZ/4) << idx)); |
0929c2dd RZ |
195 | |
196 | list_add_rcu(&est->list, &elist[idx].list); | |
1da177e4 LT |
197 | return 0; |
198 | } | |
199 | ||
0929c2dd RZ |
200 | static void __gen_kill_estimator(struct rcu_head *head) |
201 | { | |
202 | struct gen_estimator *e = container_of(head, | |
203 | struct gen_estimator, e_rcu); | |
204 | kfree(e); | |
205 | } | |
206 | ||
1da177e4 LT |
207 | /** |
208 | * gen_kill_estimator - remove a rate estimator | |
209 | * @bstats: basic statistics | |
210 | * @rate_est: rate estimator statistics | |
211 | * | |
212 | * Removes the rate estimator specified by &bstats and &rate_est | |
213 | * and deletes the timer. | |
0929c2dd RZ |
214 | * |
215 | * NOTE: Called under rtnl_mutex | |
1da177e4 LT |
216 | */ |
217 | void gen_kill_estimator(struct gnet_stats_basic *bstats, | |
218 | struct gnet_stats_rate_est *rate_est) | |
219 | { | |
220 | int idx; | |
0929c2dd | 221 | struct gen_estimator *e, *n; |
1da177e4 LT |
222 | |
223 | for (idx=0; idx <= EST_MAX_INTERVAL; idx++) { | |
0929c2dd RZ |
224 | |
225 | /* Skip non initialized indexes */ | |
226 | if (!elist[idx].timer.function) | |
227 | continue; | |
228 | ||
229 | list_for_each_entry_safe(e, n, &elist[idx].list, list) { | |
230 | if (e->rate_est != rate_est || e->bstats != bstats) | |
1da177e4 | 231 | continue; |
1da177e4 LT |
232 | |
233 | write_lock_bh(&est_lock); | |
0929c2dd | 234 | e->bstats = NULL; |
1da177e4 LT |
235 | write_unlock_bh(&est_lock); |
236 | ||
0929c2dd RZ |
237 | list_del_rcu(&e->list); |
238 | call_rcu(&e->e_rcu, __gen_kill_estimator); | |
1da177e4 | 239 | } |
1da177e4 LT |
240 | } |
241 | } | |
242 | ||
243 | /** | |
96750162 | 244 | * gen_replace_estimator - replace rate estimator configuration |
1da177e4 LT |
245 | * @bstats: basic statistics |
246 | * @rate_est: rate estimator statistics | |
247 | * @stats_lock: statistics lock | |
248 | * @opt: rate estimator configuration TLV | |
249 | * | |
250 | * Replaces the configuration of a rate estimator by calling | |
251 | * gen_kill_estimator() and gen_new_estimator(). | |
4ec93edb | 252 | * |
1da177e4 LT |
253 | * Returns 0 on success or a negative error code. |
254 | */ | |
96750162 JP |
255 | int gen_replace_estimator(struct gnet_stats_basic *bstats, |
256 | struct gnet_stats_rate_est *rate_est, | |
1e90474c | 257 | spinlock_t *stats_lock, struct nlattr *opt) |
1da177e4 | 258 | { |
96750162 JP |
259 | gen_kill_estimator(bstats, rate_est); |
260 | return gen_new_estimator(bstats, rate_est, stats_lock, opt); | |
1da177e4 | 261 | } |
4ec93edb | 262 | |
1da177e4 LT |
263 | |
264 | EXPORT_SYMBOL(gen_kill_estimator); | |
265 | EXPORT_SYMBOL(gen_new_estimator); | |
266 | EXPORT_SYMBOL(gen_replace_estimator); |