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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 <linux/bitops.h>
18#include <linux/module.h>
19#include <linux/types.h>
20#include <linux/kernel.h>
21#include <linux/jiffies.h>
22#include <linux/string.h>
23#include <linux/mm.h>
24#include <linux/socket.h>
25#include <linux/sockios.h>
26#include <linux/in.h>
27#include <linux/errno.h>
28#include <linux/interrupt.h>
29#include <linux/netdevice.h>
30#include <linux/skbuff.h>
31#include <linux/rtnetlink.h>
32#include <linux/init.h>
33#include <linux/rbtree.h>
34#include <linux/slab.h>
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 * avbps is scaled by 2^5, avpps is scaled by 2^10.
70 * both values are reported as 32 bit unsigned values. bps can
71 overflow for fast links : max speed being 34360Mbit/sec
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
81struct gen_estimator
82{
83 struct list_head list;
84 struct gnet_stats_basic_packed *bstats;
85 struct gnet_stats_rate_est *rate_est;
86 spinlock_t *stats_lock;
87 int ewma_log;
88 u64 last_bytes;
89 u64 avbps;
90 u32 last_packets;
91 u32 avpps;
92 struct rcu_head e_rcu;
93 struct rb_node node;
94};
95
96struct gen_estimator_head
97{
98 struct timer_list timer;
99 struct list_head list;
100};
101
102static struct gen_estimator_head elist[EST_MAX_INTERVAL+1];
103
104/* Protects against NULL dereference */
105static DEFINE_RWLOCK(est_lock);
106
107/* Protects against soft lockup during large deletion */
108static struct rb_root est_root = RB_ROOT;
109static DEFINE_SPINLOCK(est_tree_lock);
110
111static void est_timer(unsigned long arg)
112{
113 int idx = (int)arg;
114 struct gen_estimator *e;
115
116 rcu_read_lock();
117 list_for_each_entry_rcu(e, &elist[idx].list, list) {
118 u64 nbytes;
119 u64 brate;
120 u32 npackets;
121 u32 rate;
122
123 spin_lock(e->stats_lock);
124 read_lock(&est_lock);
125 if (e->bstats == NULL)
126 goto skip;
127
128 nbytes = e->bstats->bytes;
129 npackets = e->bstats->packets;
130 brate = (nbytes - e->last_bytes)<<(7 - idx);
131 e->last_bytes = nbytes;
132 e->avbps += (brate >> e->ewma_log) - (e->avbps >> e->ewma_log);
133 e->rate_est->bps = (e->avbps+0xF)>>5;
134
135 rate = (npackets - e->last_packets)<<(12 - idx);
136 e->last_packets = npackets;
137 e->avpps += (rate >> e->ewma_log) - (e->avpps >> e->ewma_log);
138 e->rate_est->pps = (e->avpps+0x1FF)>>10;
139skip:
140 read_unlock(&est_lock);
141 spin_unlock(e->stats_lock);
142 }
143
144 if (!list_empty(&elist[idx].list))
145 mod_timer(&elist[idx].timer, jiffies + ((HZ/4) << idx));
146 rcu_read_unlock();
147}
148
149static void gen_add_node(struct gen_estimator *est)
150{
151 struct rb_node **p = &est_root.rb_node, *parent = NULL;
152
153 while (*p) {
154 struct gen_estimator *e;
155
156 parent = *p;
157 e = rb_entry(parent, struct gen_estimator, node);
158
159 if (est->bstats > e->bstats)
160 p = &parent->rb_right;
161 else
162 p = &parent->rb_left;
163 }
164 rb_link_node(&est->node, parent, p);
165 rb_insert_color(&est->node, &est_root);
166}
167
168static
169struct gen_estimator *gen_find_node(const struct gnet_stats_basic_packed *bstats,
170 const struct gnet_stats_rate_est *rate_est)
171{
172 struct rb_node *p = est_root.rb_node;
173
174 while (p) {
175 struct gen_estimator *e;
176
177 e = rb_entry(p, struct gen_estimator, node);
178
179 if (bstats > e->bstats)
180 p = p->rb_right;
181 else if (bstats < e->bstats || rate_est != e->rate_est)
182 p = p->rb_left;
183 else
184 return e;
185 }
186 return NULL;
187}
188
189/**
190 * gen_new_estimator - create a new rate estimator
191 * @bstats: basic statistics
192 * @rate_est: rate estimator statistics
193 * @stats_lock: statistics lock
194 * @opt: rate estimator configuration TLV
195 *
196 * Creates a new rate estimator with &bstats as source and &rate_est
197 * as destination. A new timer with the interval specified in the
198 * configuration TLV is created. Upon each interval, the latest statistics
199 * will be read from &bstats and the estimated rate will be stored in
200 * &rate_est with the statistics lock grabed during this period.
201 *
202 * Returns 0 on success or a negative error code.
203 *
204 */
205int gen_new_estimator(struct gnet_stats_basic_packed *bstats,
206 struct gnet_stats_rate_est *rate_est,
207 spinlock_t *stats_lock,
208 struct nlattr *opt)
209{
210 struct gen_estimator *est;
211 struct gnet_estimator *parm = nla_data(opt);
212 int idx;
213
214 if (nla_len(opt) < sizeof(*parm))
215 return -EINVAL;
216
217 if (parm->interval < -2 || parm->interval > 3)
218 return -EINVAL;
219
220 est = kzalloc(sizeof(*est), GFP_KERNEL);
221 if (est == NULL)
222 return -ENOBUFS;
223
224 idx = parm->interval + 2;
225 est->bstats = bstats;
226 est->rate_est = rate_est;
227 est->stats_lock = stats_lock;
228 est->ewma_log = parm->ewma_log;
229 est->last_bytes = bstats->bytes;
230 est->avbps = rate_est->bps<<5;
231 est->last_packets = bstats->packets;
232 est->avpps = rate_est->pps<<10;
233
234 spin_lock_bh(&est_tree_lock);
235 if (!elist[idx].timer.function) {
236 INIT_LIST_HEAD(&elist[idx].list);
237 setup_timer(&elist[idx].timer, est_timer, idx);
238 }
239
240 if (list_empty(&elist[idx].list))
241 mod_timer(&elist[idx].timer, jiffies + ((HZ/4) << idx));
242
243 list_add_rcu(&est->list, &elist[idx].list);
244 gen_add_node(est);
245 spin_unlock_bh(&est_tree_lock);
246
247 return 0;
248}
249EXPORT_SYMBOL(gen_new_estimator);
250
251/**
252 * gen_kill_estimator - remove a rate estimator
253 * @bstats: basic statistics
254 * @rate_est: rate estimator statistics
255 *
256 * Removes the rate estimator specified by &bstats and &rate_est.
257 *
258 * Note : Caller should respect an RCU grace period before freeing stats_lock
259 */
260void gen_kill_estimator(struct gnet_stats_basic_packed *bstats,
261 struct gnet_stats_rate_est *rate_est)
262{
263 struct gen_estimator *e;
264
265 spin_lock_bh(&est_tree_lock);
266 while ((e = gen_find_node(bstats, rate_est))) {
267 rb_erase(&e->node, &est_root);
268
269 write_lock(&est_lock);
270 e->bstats = NULL;
271 write_unlock(&est_lock);
272
273 list_del_rcu(&e->list);
274 kfree_rcu(e, e_rcu);
275 }
276 spin_unlock_bh(&est_tree_lock);
277}
278EXPORT_SYMBOL(gen_kill_estimator);
279
280/**
281 * gen_replace_estimator - replace rate estimator configuration
282 * @bstats: basic statistics
283 * @rate_est: rate estimator statistics
284 * @stats_lock: statistics lock
285 * @opt: rate estimator configuration TLV
286 *
287 * Replaces the configuration of a rate estimator by calling
288 * gen_kill_estimator() and gen_new_estimator().
289 *
290 * Returns 0 on success or a negative error code.
291 */
292int gen_replace_estimator(struct gnet_stats_basic_packed *bstats,
293 struct gnet_stats_rate_est *rate_est,
294 spinlock_t *stats_lock, struct nlattr *opt)
295{
296 gen_kill_estimator(bstats, rate_est);
297 return gen_new_estimator(bstats, rate_est, stats_lock, opt);
298}
299EXPORT_SYMBOL(gen_replace_estimator);
300
301/**
302 * gen_estimator_active - test if estimator is currently in use
303 * @bstats: basic statistics
304 * @rate_est: rate estimator statistics
305 *
306 * Returns true if estimator is active, and false if not.
307 */
308bool gen_estimator_active(const struct gnet_stats_basic_packed *bstats,
309 const struct gnet_stats_rate_est *rate_est)
310{
311 bool res;
312
313 ASSERT_RTNL();
314
315 spin_lock_bh(&est_tree_lock);
316 res = gen_find_node(bstats, rate_est) != NULL;
317 spin_unlock_bh(&est_tree_lock);
318
319 return res;
320}
321EXPORT_SYMBOL(gen_estimator_active);
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 <linux/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 <linux/rbtree.h>
35#include <linux/slab.h>
36#include <net/sock.h>
37#include <net/gen_stats.h>
38
39/*
40 This code is NOT intended to be used for statistics collection,
41 its purpose is to provide a base for statistical multiplexing
42 for controlled load service.
43 If you need only statistics, run a user level daemon which
44 periodically reads byte counters.
45
46 Unfortunately, rate estimation is not a very easy task.
47 F.e. I did not find a simple way to estimate the current peak rate
48 and even failed to formulate the problem 8)8)
49
50 So I preferred not to built an estimator into the scheduler,
51 but run this task separately.
52 Ideally, it should be kernel thread(s), but for now it runs
53 from timers, which puts apparent top bounds on the number of rated
54 flows, has minimal overhead on small, but is enough
55 to handle controlled load service, sets of aggregates.
56
57 We measure rate over A=(1<<interval) seconds and evaluate EWMA:
58
59 avrate = avrate*(1-W) + rate*W
60
61 where W is chosen as negative power of 2: W = 2^(-ewma_log)
62
63 The resulting time constant is:
64
65 T = A/(-ln(1-W))
66
67
68 NOTES.
69
70 * avbps is scaled by 2^5, avpps is scaled by 2^10.
71 * both values are reported as 32 bit unsigned values. bps can
72 overflow for fast links : max speed being 34360Mbit/sec
73 * Minimal interval is HZ/4=250msec (it is the greatest common divisor
74 for HZ=100 and HZ=1024 8)), maximal interval
75 is (HZ*2^EST_MAX_INTERVAL)/4 = 8sec. Shorter intervals
76 are too expensive, longer ones can be implemented
77 at user level painlessly.
78 */
79
80#define EST_MAX_INTERVAL 5
81
82struct gen_estimator
83{
84 struct list_head list;
85 struct gnet_stats_basic_packed *bstats;
86 struct gnet_stats_rate_est *rate_est;
87 spinlock_t *stats_lock;
88 int ewma_log;
89 u64 last_bytes;
90 u64 avbps;
91 u32 last_packets;
92 u32 avpps;
93 struct rcu_head e_rcu;
94 struct rb_node node;
95};
96
97struct gen_estimator_head
98{
99 struct timer_list timer;
100 struct list_head list;
101};
102
103static struct gen_estimator_head elist[EST_MAX_INTERVAL+1];
104
105/* Protects against NULL dereference */
106static DEFINE_RWLOCK(est_lock);
107
108/* Protects against soft lockup during large deletion */
109static struct rb_root est_root = RB_ROOT;
110static DEFINE_SPINLOCK(est_tree_lock);
111
112static void est_timer(unsigned long arg)
113{
114 int idx = (int)arg;
115 struct gen_estimator *e;
116
117 rcu_read_lock();
118 list_for_each_entry_rcu(e, &elist[idx].list, list) {
119 u64 nbytes;
120 u64 brate;
121 u32 npackets;
122 u32 rate;
123
124 spin_lock(e->stats_lock);
125 read_lock(&est_lock);
126 if (e->bstats == NULL)
127 goto skip;
128
129 nbytes = e->bstats->bytes;
130 npackets = e->bstats->packets;
131 brate = (nbytes - e->last_bytes)<<(7 - idx);
132 e->last_bytes = nbytes;
133 e->avbps += (brate >> e->ewma_log) - (e->avbps >> e->ewma_log);
134 e->rate_est->bps = (e->avbps+0xF)>>5;
135
136 rate = (npackets - e->last_packets)<<(12 - idx);
137 e->last_packets = npackets;
138 e->avpps += (rate >> e->ewma_log) - (e->avpps >> e->ewma_log);
139 e->rate_est->pps = (e->avpps+0x1FF)>>10;
140skip:
141 read_unlock(&est_lock);
142 spin_unlock(e->stats_lock);
143 }
144
145 if (!list_empty(&elist[idx].list))
146 mod_timer(&elist[idx].timer, jiffies + ((HZ/4) << idx));
147 rcu_read_unlock();
148}
149
150static void gen_add_node(struct gen_estimator *est)
151{
152 struct rb_node **p = &est_root.rb_node, *parent = NULL;
153
154 while (*p) {
155 struct gen_estimator *e;
156
157 parent = *p;
158 e = rb_entry(parent, struct gen_estimator, node);
159
160 if (est->bstats > e->bstats)
161 p = &parent->rb_right;
162 else
163 p = &parent->rb_left;
164 }
165 rb_link_node(&est->node, parent, p);
166 rb_insert_color(&est->node, &est_root);
167}
168
169static
170struct gen_estimator *gen_find_node(const struct gnet_stats_basic_packed *bstats,
171 const struct gnet_stats_rate_est *rate_est)
172{
173 struct rb_node *p = est_root.rb_node;
174
175 while (p) {
176 struct gen_estimator *e;
177
178 e = rb_entry(p, struct gen_estimator, node);
179
180 if (bstats > e->bstats)
181 p = p->rb_right;
182 else if (bstats < e->bstats || rate_est != e->rate_est)
183 p = p->rb_left;
184 else
185 return e;
186 }
187 return NULL;
188}
189
190/**
191 * gen_new_estimator - create a new rate estimator
192 * @bstats: basic statistics
193 * @rate_est: rate estimator statistics
194 * @stats_lock: statistics lock
195 * @opt: rate estimator configuration TLV
196 *
197 * Creates a new rate estimator with &bstats as source and &rate_est
198 * as destination. A new timer with the interval specified in the
199 * configuration TLV is created. Upon each interval, the latest statistics
200 * will be read from &bstats and the estimated rate will be stored in
201 * &rate_est with the statistics lock grabed during this period.
202 *
203 * Returns 0 on success or a negative error code.
204 *
205 */
206int gen_new_estimator(struct gnet_stats_basic_packed *bstats,
207 struct gnet_stats_rate_est *rate_est,
208 spinlock_t *stats_lock,
209 struct nlattr *opt)
210{
211 struct gen_estimator *est;
212 struct gnet_estimator *parm = nla_data(opt);
213 int idx;
214
215 if (nla_len(opt) < sizeof(*parm))
216 return -EINVAL;
217
218 if (parm->interval < -2 || parm->interval > 3)
219 return -EINVAL;
220
221 est = kzalloc(sizeof(*est), GFP_KERNEL);
222 if (est == NULL)
223 return -ENOBUFS;
224
225 idx = parm->interval + 2;
226 est->bstats = bstats;
227 est->rate_est = rate_est;
228 est->stats_lock = stats_lock;
229 est->ewma_log = parm->ewma_log;
230 est->last_bytes = bstats->bytes;
231 est->avbps = rate_est->bps<<5;
232 est->last_packets = bstats->packets;
233 est->avpps = rate_est->pps<<10;
234
235 spin_lock_bh(&est_tree_lock);
236 if (!elist[idx].timer.function) {
237 INIT_LIST_HEAD(&elist[idx].list);
238 setup_timer(&elist[idx].timer, est_timer, idx);
239 }
240
241 if (list_empty(&elist[idx].list))
242 mod_timer(&elist[idx].timer, jiffies + ((HZ/4) << idx));
243
244 list_add_rcu(&est->list, &elist[idx].list);
245 gen_add_node(est);
246 spin_unlock_bh(&est_tree_lock);
247
248 return 0;
249}
250EXPORT_SYMBOL(gen_new_estimator);
251
252/**
253 * gen_kill_estimator - remove a rate estimator
254 * @bstats: basic statistics
255 * @rate_est: rate estimator statistics
256 *
257 * Removes the rate estimator specified by &bstats and &rate_est.
258 *
259 * Note : Caller should respect an RCU grace period before freeing stats_lock
260 */
261void gen_kill_estimator(struct gnet_stats_basic_packed *bstats,
262 struct gnet_stats_rate_est *rate_est)
263{
264 struct gen_estimator *e;
265
266 spin_lock_bh(&est_tree_lock);
267 while ((e = gen_find_node(bstats, rate_est))) {
268 rb_erase(&e->node, &est_root);
269
270 write_lock(&est_lock);
271 e->bstats = NULL;
272 write_unlock(&est_lock);
273
274 list_del_rcu(&e->list);
275 kfree_rcu(e, e_rcu);
276 }
277 spin_unlock_bh(&est_tree_lock);
278}
279EXPORT_SYMBOL(gen_kill_estimator);
280
281/**
282 * gen_replace_estimator - replace rate estimator configuration
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().
290 *
291 * Returns 0 on success or a negative error code.
292 */
293int gen_replace_estimator(struct gnet_stats_basic_packed *bstats,
294 struct gnet_stats_rate_est *rate_est,
295 spinlock_t *stats_lock, struct nlattr *opt)
296{
297 gen_kill_estimator(bstats, rate_est);
298 return gen_new_estimator(bstats, rate_est, stats_lock, opt);
299}
300EXPORT_SYMBOL(gen_replace_estimator);
301
302/**
303 * gen_estimator_active - test if estimator is currently in use
304 * @bstats: basic statistics
305 * @rate_est: rate estimator statistics
306 *
307 * Returns true if estimator is active, and false if not.
308 */
309bool gen_estimator_active(const struct gnet_stats_basic_packed *bstats,
310 const struct gnet_stats_rate_est *rate_est)
311{
312 bool res;
313
314 ASSERT_RTNL();
315
316 spin_lock_bh(&est_tree_lock);
317 res = gen_find_node(bstats, rate_est) != NULL;
318 spin_unlock_bh(&est_tree_lock);
319
320 return res;
321}
322EXPORT_SYMBOL(gen_estimator_active);