Commit | Line | Data |
---|---|---|
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> | |
18 | #include <asm/bitops.h> | |
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 | { | |
82 | struct gen_estimator *next; | |
83 | struct gnet_stats_basic *bstats; | |
84 | struct gnet_stats_rate_est *rate_est; | |
85 | spinlock_t *stats_lock; | |
86 | unsigned interval; | |
87 | int ewma_log; | |
88 | u64 last_bytes; | |
89 | u32 last_packets; | |
90 | u32 avpps; | |
91 | u32 avbps; | |
92 | }; | |
93 | ||
94 | struct gen_estimator_head | |
95 | { | |
96 | struct timer_list timer; | |
97 | struct gen_estimator *list; | |
98 | }; | |
99 | ||
100 | static struct gen_estimator_head elist[EST_MAX_INTERVAL+1]; | |
101 | ||
102 | /* Estimator array lock */ | |
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 | ||
110 | read_lock(&est_lock); | |
111 | for (e = elist[idx].list; e; e = e->next) { | |
112 | u64 nbytes; | |
113 | u32 npackets; | |
114 | u32 rate; | |
115 | ||
116 | spin_lock(e->stats_lock); | |
117 | nbytes = e->bstats->bytes; | |
118 | npackets = e->bstats->packets; | |
119 | rate = (nbytes - e->last_bytes)<<(7 - idx); | |
120 | e->last_bytes = nbytes; | |
121 | e->avbps += ((long)rate - (long)e->avbps) >> e->ewma_log; | |
122 | e->rate_est->bps = (e->avbps+0xF)>>5; | |
123 | ||
124 | rate = (npackets - e->last_packets)<<(12 - idx); | |
125 | e->last_packets = npackets; | |
126 | e->avpps += ((long)rate - (long)e->avpps) >> e->ewma_log; | |
127 | e->rate_est->pps = (e->avpps+0x1FF)>>10; | |
128 | spin_unlock(e->stats_lock); | |
129 | } | |
130 | ||
131 | mod_timer(&elist[idx].timer, jiffies + ((HZ<<idx)/4)); | |
132 | read_unlock(&est_lock); | |
133 | } | |
134 | ||
135 | /** | |
136 | * gen_new_estimator - create a new rate estimator | |
137 | * @bstats: basic statistics | |
138 | * @rate_est: rate estimator statistics | |
139 | * @stats_lock: statistics lock | |
140 | * @opt: rate estimator configuration TLV | |
141 | * | |
142 | * Creates a new rate estimator with &bstats as source and &rate_est | |
143 | * as destination. A new timer with the interval specified in the | |
144 | * configuration TLV is created. Upon each interval, the latest statistics | |
145 | * will be read from &bstats and the estimated rate will be stored in | |
146 | * &rate_est with the statistics lock grabed during this period. | |
147 | * | |
148 | * Returns 0 on success or a negative error code. | |
149 | */ | |
150 | int gen_new_estimator(struct gnet_stats_basic *bstats, | |
151 | struct gnet_stats_rate_est *rate_est, spinlock_t *stats_lock, struct rtattr *opt) | |
152 | { | |
153 | struct gen_estimator *est; | |
154 | struct gnet_estimator *parm = RTA_DATA(opt); | |
155 | ||
156 | if (RTA_PAYLOAD(opt) < sizeof(*parm)) | |
157 | return -EINVAL; | |
158 | ||
159 | if (parm->interval < -2 || parm->interval > 3) | |
160 | return -EINVAL; | |
161 | ||
162 | est = kmalloc(sizeof(*est), GFP_KERNEL); | |
163 | if (est == NULL) | |
164 | return -ENOBUFS; | |
165 | ||
166 | memset(est, 0, sizeof(*est)); | |
167 | est->interval = parm->interval + 2; | |
168 | est->bstats = bstats; | |
169 | est->rate_est = rate_est; | |
170 | est->stats_lock = stats_lock; | |
171 | est->ewma_log = parm->ewma_log; | |
172 | est->last_bytes = bstats->bytes; | |
173 | est->avbps = rate_est->bps<<5; | |
174 | est->last_packets = bstats->packets; | |
175 | est->avpps = rate_est->pps<<10; | |
176 | ||
177 | est->next = elist[est->interval].list; | |
178 | if (est->next == NULL) { | |
179 | init_timer(&elist[est->interval].timer); | |
180 | elist[est->interval].timer.data = est->interval; | |
181 | elist[est->interval].timer.expires = jiffies + ((HZ<<est->interval)/4); | |
182 | elist[est->interval].timer.function = est_timer; | |
183 | add_timer(&elist[est->interval].timer); | |
184 | } | |
185 | write_lock_bh(&est_lock); | |
186 | elist[est->interval].list = est; | |
187 | write_unlock_bh(&est_lock); | |
188 | return 0; | |
189 | } | |
190 | ||
191 | /** | |
192 | * gen_kill_estimator - remove a rate estimator | |
193 | * @bstats: basic statistics | |
194 | * @rate_est: rate estimator statistics | |
195 | * | |
196 | * Removes the rate estimator specified by &bstats and &rate_est | |
197 | * and deletes the timer. | |
198 | */ | |
199 | void gen_kill_estimator(struct gnet_stats_basic *bstats, | |
200 | struct gnet_stats_rate_est *rate_est) | |
201 | { | |
202 | int idx; | |
203 | struct gen_estimator *est, **pest; | |
204 | ||
205 | for (idx=0; idx <= EST_MAX_INTERVAL; idx++) { | |
206 | int killed = 0; | |
207 | pest = &elist[idx].list; | |
208 | while ((est=*pest) != NULL) { | |
209 | if (est->rate_est != rate_est || est->bstats != bstats) { | |
210 | pest = &est->next; | |
211 | continue; | |
212 | } | |
213 | ||
214 | write_lock_bh(&est_lock); | |
215 | *pest = est->next; | |
216 | write_unlock_bh(&est_lock); | |
217 | ||
218 | kfree(est); | |
219 | killed++; | |
220 | } | |
221 | if (killed && elist[idx].list == NULL) | |
222 | del_timer(&elist[idx].timer); | |
223 | } | |
224 | } | |
225 | ||
226 | /** | |
227 | * gen_replace_estimator - replace rate estimator configruation | |
228 | * @bstats: basic statistics | |
229 | * @rate_est: rate estimator statistics | |
230 | * @stats_lock: statistics lock | |
231 | * @opt: rate estimator configuration TLV | |
232 | * | |
233 | * Replaces the configuration of a rate estimator by calling | |
234 | * gen_kill_estimator() and gen_new_estimator(). | |
235 | * | |
236 | * Returns 0 on success or a negative error code. | |
237 | */ | |
238 | int | |
239 | gen_replace_estimator(struct gnet_stats_basic *bstats, | |
240 | struct gnet_stats_rate_est *rate_est, spinlock_t *stats_lock, | |
241 | struct rtattr *opt) | |
242 | { | |
243 | gen_kill_estimator(bstats, rate_est); | |
244 | return gen_new_estimator(bstats, rate_est, stats_lock, opt); | |
245 | } | |
246 | ||
247 | ||
248 | EXPORT_SYMBOL(gen_kill_estimator); | |
249 | EXPORT_SYMBOL(gen_new_estimator); | |
250 | EXPORT_SYMBOL(gen_replace_estimator); |