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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> | |
4db0acf3 | 34 | #include <linux/rbtree.h> |
1da177e4 LT |
35 | #include <net/sock.h> |
36 | #include <net/gen_stats.h> | |
37 | ||
38 | /* | |
39 | This code is NOT intended to be used for statistics collection, | |
40 | its purpose is to provide a base for statistical multiplexing | |
41 | for controlled load service. | |
42 | If you need only statistics, run a user level daemon which | |
43 | periodically reads byte counters. | |
44 | ||
45 | Unfortunately, rate estimation is not a very easy task. | |
46 | F.e. I did not find a simple way to estimate the current peak rate | |
47 | and even failed to formulate the problem 8)8) | |
48 | ||
49 | So I preferred not to built an estimator into the scheduler, | |
50 | but run this task separately. | |
51 | Ideally, it should be kernel thread(s), but for now it runs | |
52 | from timers, which puts apparent top bounds on the number of rated | |
53 | flows, has minimal overhead on small, but is enough | |
54 | to handle controlled load service, sets of aggregates. | |
55 | ||
56 | We measure rate over A=(1<<interval) seconds and evaluate EWMA: | |
57 | ||
58 | avrate = avrate*(1-W) + rate*W | |
59 | ||
60 | where W is chosen as negative power of 2: W = 2^(-ewma_log) | |
61 | ||
62 | The resulting time constant is: | |
63 | ||
64 | T = A/(-ln(1-W)) | |
65 | ||
66 | ||
67 | NOTES. | |
68 | ||
69 | * The stored value for avbps is scaled by 2^5, so that maximal | |
70 | rate is ~1Gbit, avpps is scaled by 2^10. | |
71 | ||
72 | * Minimal interval is HZ/4=250msec (it is the greatest common divisor | |
73 | for HZ=100 and HZ=1024 8)), maximal interval | |
74 | is (HZ*2^EST_MAX_INTERVAL)/4 = 8sec. Shorter intervals | |
75 | are too expensive, longer ones can be implemented | |
76 | at user level painlessly. | |
77 | */ | |
78 | ||
79 | #define EST_MAX_INTERVAL 5 | |
80 | ||
81 | struct gen_estimator | |
82 | { | |
0929c2dd | 83 | struct list_head list; |
1da177e4 LT |
84 | struct gnet_stats_basic *bstats; |
85 | struct gnet_stats_rate_est *rate_est; | |
86 | spinlock_t *stats_lock; | |
1da177e4 LT |
87 | int ewma_log; |
88 | u64 last_bytes; | |
89 | u32 last_packets; | |
90 | u32 avpps; | |
91 | u32 avbps; | |
0929c2dd | 92 | struct rcu_head e_rcu; |
4db0acf3 | 93 | struct rb_node node; |
1da177e4 LT |
94 | }; |
95 | ||
96 | struct gen_estimator_head | |
97 | { | |
98 | struct timer_list timer; | |
0929c2dd | 99 | struct list_head list; |
1da177e4 LT |
100 | }; |
101 | ||
102 | static struct gen_estimator_head elist[EST_MAX_INTERVAL+1]; | |
103 | ||
deb3abf1 | 104 | /* Protects against NULL dereference */ |
1da177e4 LT |
105 | static DEFINE_RWLOCK(est_lock); |
106 | ||
4db0acf3 JP |
107 | /* Protects against soft lockup during large deletion */ |
108 | static struct rb_root est_root = RB_ROOT; | |
109 | ||
1da177e4 LT |
110 | static void est_timer(unsigned long arg) |
111 | { | |
112 | int idx = (int)arg; | |
113 | struct gen_estimator *e; | |
114 | ||
0929c2dd RZ |
115 | rcu_read_lock(); |
116 | list_for_each_entry_rcu(e, &elist[idx].list, list) { | |
1da177e4 LT |
117 | u64 nbytes; |
118 | u32 npackets; | |
119 | u32 rate; | |
120 | ||
121 | spin_lock(e->stats_lock); | |
0929c2dd RZ |
122 | read_lock(&est_lock); |
123 | if (e->bstats == NULL) | |
124 | goto skip; | |
125 | ||
1da177e4 LT |
126 | nbytes = e->bstats->bytes; |
127 | npackets = e->bstats->packets; | |
128 | rate = (nbytes - e->last_bytes)<<(7 - idx); | |
129 | e->last_bytes = nbytes; | |
130 | e->avbps += ((long)rate - (long)e->avbps) >> e->ewma_log; | |
131 | e->rate_est->bps = (e->avbps+0xF)>>5; | |
132 | ||
133 | rate = (npackets - e->last_packets)<<(12 - idx); | |
134 | e->last_packets = npackets; | |
135 | e->avpps += ((long)rate - (long)e->avpps) >> e->ewma_log; | |
136 | e->rate_est->pps = (e->avpps+0x1FF)>>10; | |
0929c2dd RZ |
137 | skip: |
138 | read_unlock(&est_lock); | |
1da177e4 LT |
139 | spin_unlock(e->stats_lock); |
140 | } | |
141 | ||
0929c2dd | 142 | if (!list_empty(&elist[idx].list)) |
789675e2 | 143 | mod_timer(&elist[idx].timer, jiffies + ((HZ/4) << idx)); |
0929c2dd | 144 | rcu_read_unlock(); |
1da177e4 LT |
145 | } |
146 | ||
4db0acf3 JP |
147 | static void gen_add_node(struct gen_estimator *est) |
148 | { | |
149 | struct rb_node **p = &est_root.rb_node, *parent = NULL; | |
150 | ||
151 | while (*p) { | |
152 | struct gen_estimator *e; | |
153 | ||
154 | parent = *p; | |
155 | e = rb_entry(parent, struct gen_estimator, node); | |
156 | ||
157 | if (est->bstats > e->bstats) | |
158 | p = &parent->rb_right; | |
159 | else | |
160 | p = &parent->rb_left; | |
161 | } | |
162 | rb_link_node(&est->node, parent, p); | |
163 | rb_insert_color(&est->node, &est_root); | |
164 | } | |
165 | ||
166 | static struct gen_estimator *gen_find_node(struct gnet_stats_basic *bstats, | |
167 | struct gnet_stats_rate_est *rate_est) | |
168 | { | |
169 | struct rb_node *p = est_root.rb_node; | |
170 | ||
171 | while (p) { | |
172 | struct gen_estimator *e; | |
173 | ||
174 | e = rb_entry(p, struct gen_estimator, node); | |
175 | ||
176 | if (bstats > e->bstats) | |
177 | p = p->rb_right; | |
178 | else if (bstats < e->bstats || rate_est != e->rate_est) | |
179 | p = p->rb_left; | |
180 | else | |
181 | return e; | |
182 | } | |
183 | return NULL; | |
184 | } | |
185 | ||
1da177e4 LT |
186 | /** |
187 | * gen_new_estimator - create a new rate estimator | |
188 | * @bstats: basic statistics | |
189 | * @rate_est: rate estimator statistics | |
190 | * @stats_lock: statistics lock | |
191 | * @opt: rate estimator configuration TLV | |
192 | * | |
193 | * Creates a new rate estimator with &bstats as source and &rate_est | |
194 | * as destination. A new timer with the interval specified in the | |
195 | * configuration TLV is created. Upon each interval, the latest statistics | |
196 | * will be read from &bstats and the estimated rate will be stored in | |
197 | * &rate_est with the statistics lock grabed during this period. | |
4ec93edb | 198 | * |
1da177e4 | 199 | * Returns 0 on success or a negative error code. |
0929c2dd RZ |
200 | * |
201 | * NOTE: Called under rtnl_mutex | |
1da177e4 LT |
202 | */ |
203 | int gen_new_estimator(struct gnet_stats_basic *bstats, | |
0929c2dd RZ |
204 | struct gnet_stats_rate_est *rate_est, |
205 | spinlock_t *stats_lock, | |
1e90474c | 206 | struct nlattr *opt) |
1da177e4 LT |
207 | { |
208 | struct gen_estimator *est; | |
1e90474c | 209 | struct gnet_estimator *parm = nla_data(opt); |
0929c2dd | 210 | int idx; |
1da177e4 | 211 | |
1e90474c | 212 | if (nla_len(opt) < sizeof(*parm)) |
1da177e4 LT |
213 | return -EINVAL; |
214 | ||
215 | if (parm->interval < -2 || parm->interval > 3) | |
216 | return -EINVAL; | |
217 | ||
77d04bd9 | 218 | est = kzalloc(sizeof(*est), GFP_KERNEL); |
1da177e4 LT |
219 | if (est == NULL) |
220 | return -ENOBUFS; | |
221 | ||
0929c2dd | 222 | idx = parm->interval + 2; |
1da177e4 LT |
223 | est->bstats = bstats; |
224 | est->rate_est = rate_est; | |
225 | est->stats_lock = stats_lock; | |
226 | est->ewma_log = parm->ewma_log; | |
227 | est->last_bytes = bstats->bytes; | |
228 | est->avbps = rate_est->bps<<5; | |
229 | est->last_packets = bstats->packets; | |
230 | est->avpps = rate_est->pps<<10; | |
231 | ||
0929c2dd RZ |
232 | if (!elist[idx].timer.function) { |
233 | INIT_LIST_HEAD(&elist[idx].list); | |
234 | setup_timer(&elist[idx].timer, est_timer, idx); | |
1da177e4 | 235 | } |
0929c2dd RZ |
236 | |
237 | if (list_empty(&elist[idx].list)) | |
789675e2 | 238 | mod_timer(&elist[idx].timer, jiffies + ((HZ/4) << idx)); |
0929c2dd RZ |
239 | |
240 | list_add_rcu(&est->list, &elist[idx].list); | |
4db0acf3 JP |
241 | gen_add_node(est); |
242 | ||
1da177e4 LT |
243 | return 0; |
244 | } | |
c1b56878 | 245 | EXPORT_SYMBOL(gen_new_estimator); |
1da177e4 | 246 | |
0929c2dd RZ |
247 | static void __gen_kill_estimator(struct rcu_head *head) |
248 | { | |
249 | struct gen_estimator *e = container_of(head, | |
250 | struct gen_estimator, e_rcu); | |
251 | kfree(e); | |
252 | } | |
253 | ||
1da177e4 LT |
254 | /** |
255 | * gen_kill_estimator - remove a rate estimator | |
256 | * @bstats: basic statistics | |
257 | * @rate_est: rate estimator statistics | |
258 | * | |
4db0acf3 | 259 | * Removes the rate estimator specified by &bstats and &rate_est. |
0929c2dd | 260 | * |
deb3abf1 | 261 | * NOTE: Called under rtnl_mutex |
1da177e4 LT |
262 | */ |
263 | void gen_kill_estimator(struct gnet_stats_basic *bstats, | |
4db0acf3 | 264 | struct gnet_stats_rate_est *rate_est) |
1da177e4 | 265 | { |
4db0acf3 | 266 | struct gen_estimator *e; |
0929c2dd | 267 | |
4db0acf3 JP |
268 | while ((e = gen_find_node(bstats, rate_est))) { |
269 | rb_erase(&e->node, &est_root); | |
1da177e4 | 270 | |
4db0acf3 JP |
271 | write_lock_bh(&est_lock); |
272 | e->bstats = NULL; | |
273 | write_unlock_bh(&est_lock); | |
1da177e4 | 274 | |
4db0acf3 JP |
275 | list_del_rcu(&e->list); |
276 | call_rcu(&e->e_rcu, __gen_kill_estimator); | |
1da177e4 LT |
277 | } |
278 | } | |
c1b56878 | 279 | EXPORT_SYMBOL(gen_kill_estimator); |
1da177e4 LT |
280 | |
281 | /** | |
96750162 | 282 | * gen_replace_estimator - replace rate estimator configuration |
1da177e4 LT |
283 | * @bstats: basic statistics |
284 | * @rate_est: rate estimator statistics | |
285 | * @stats_lock: statistics lock | |
286 | * @opt: rate estimator configuration TLV | |
287 | * | |
288 | * Replaces the configuration of a rate estimator by calling | |
289 | * gen_kill_estimator() and gen_new_estimator(). | |
4ec93edb | 290 | * |
1da177e4 LT |
291 | * Returns 0 on success or a negative error code. |
292 | */ | |
96750162 JP |
293 | int gen_replace_estimator(struct gnet_stats_basic *bstats, |
294 | struct gnet_stats_rate_est *rate_est, | |
1e90474c | 295 | spinlock_t *stats_lock, struct nlattr *opt) |
1da177e4 | 296 | { |
96750162 JP |
297 | gen_kill_estimator(bstats, rate_est); |
298 | return gen_new_estimator(bstats, rate_est, stats_lock, opt); | |
1da177e4 | 299 | } |
c1b56878 SH |
300 | EXPORT_SYMBOL(gen_replace_estimator); |
301 | ||
302 | /** | |
303 | * gen_estimator_active - test if estimator is currently in use | |
304 | * @rate_est: rate estimator statistics | |
305 | * | |
306 | * Returns 1 if estimator is active, and 0 if not. | |
307 | */ | |
308 | int gen_estimator_active(const struct gnet_stats_rate_est *rate_est) | |
309 | { | |
310 | int idx; | |
311 | struct gen_estimator *e; | |
4ec93edb | 312 | |
c1b56878 | 313 | ASSERT_RTNL(); |
1da177e4 | 314 | |
c1b56878 SH |
315 | for (idx=0; idx <= EST_MAX_INTERVAL; idx++) { |
316 | if (!elist[idx].timer.function) | |
317 | continue; | |
318 | ||
319 | list_for_each_entry(e, &elist[idx].list, list) { | |
320 | if (e->rate_est == rate_est) | |
321 | return 1; | |
322 | } | |
323 | } | |
324 | return 0; | |
325 | } | |
326 | EXPORT_SYMBOL(gen_estimator_active); |