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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_est64 *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_est64 *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_est64 *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_est64 *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_est64 *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_est64 *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 * Eric Dumazet <edumazet@google.com>
11 *
12 * Changes:
13 * Jamal Hadi Salim - moved it to net/core and reshulfed
14 * names to make it usable in general net subsystem.
15 */
16
17#include <linux/uaccess.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/slab.h>
35#include <linux/seqlock.h>
36#include <net/sock.h>
37#include <net/gen_stats.h>
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
46struct net_rate_estimator {
47 struct gnet_stats_basic_packed *bstats;
48 spinlock_t *stats_lock;
49 seqcount_t *running;
50 struct gnet_stats_basic_cpu __percpu *cpu_bstats;
51 u8 ewma_log;
52 u8 intvl_log; /* period : (250ms << intvl_log) */
53
54 seqcount_t seq;
55 u32 last_packets;
56 u64 last_bytes;
57
58 u64 avpps;
59 u64 avbps;
60
61 unsigned long next_jiffies;
62 struct timer_list timer;
63 struct rcu_head rcu;
64};
65
66static void est_fetch_counters(struct net_rate_estimator *e,
67 struct gnet_stats_basic_packed *b)
68{
69 memset(b, 0, sizeof(*b));
70 if (e->stats_lock)
71 spin_lock(e->stats_lock);
72
73 __gnet_stats_copy_basic(e->running, b, e->cpu_bstats, e->bstats);
74
75 if (e->stats_lock)
76 spin_unlock(e->stats_lock);
77
78}
79
80static void est_timer(struct timer_list *t)
81{
82 struct net_rate_estimator *est = from_timer(est, t, timer);
83 struct gnet_stats_basic_packed b;
84 u64 rate, brate;
85
86 est_fetch_counters(est, &b);
87 brate = (b.bytes - est->last_bytes) << (10 - est->ewma_log - est->intvl_log);
88 brate -= (est->avbps >> est->ewma_log);
89
90 rate = (u64)(b.packets - est->last_packets) << (10 - est->ewma_log - est->intvl_log);
91 rate -= (est->avpps >> est->ewma_log);
92
93 write_seqcount_begin(&est->seq);
94 est->avbps += brate;
95 est->avpps += rate;
96 write_seqcount_end(&est->seq);
97
98 est->last_bytes = b.bytes;
99 est->last_packets = b.packets;
100
101 est->next_jiffies += ((HZ/4) << est->intvl_log);
102
103 if (unlikely(time_after_eq(jiffies, est->next_jiffies))) {
104 /* Ouch... timer was delayed. */
105 est->next_jiffies = jiffies + 1;
106 }
107 mod_timer(&est->timer, est->next_jiffies);
108}
109
110/**
111 * gen_new_estimator - create a new rate estimator
112 * @bstats: basic statistics
113 * @cpu_bstats: bstats per cpu
114 * @rate_est: rate estimator statistics
115 * @stats_lock: statistics lock
116 * @running: qdisc running seqcount
117 * @opt: rate estimator configuration TLV
118 *
119 * Creates a new rate estimator with &bstats as source and &rate_est
120 * as destination. A new timer with the interval specified in the
121 * configuration TLV is created. Upon each interval, the latest statistics
122 * will be read from &bstats and the estimated rate will be stored in
123 * &rate_est with the statistics lock grabbed during this period.
124 *
125 * Returns 0 on success or a negative error code.
126 *
127 */
128int gen_new_estimator(struct gnet_stats_basic_packed *bstats,
129 struct gnet_stats_basic_cpu __percpu *cpu_bstats,
130 struct net_rate_estimator __rcu **rate_est,
131 spinlock_t *stats_lock,
132 seqcount_t *running,
133 struct nlattr *opt)
134{
135 struct gnet_estimator *parm = nla_data(opt);
136 struct net_rate_estimator *old, *est;
137 struct gnet_stats_basic_packed b;
138 int intvl_log;
139
140 if (nla_len(opt) < sizeof(*parm))
141 return -EINVAL;
142
143 /* allowed timer periods are :
144 * -2 : 250ms, -1 : 500ms, 0 : 1 sec
145 * 1 : 2 sec, 2 : 4 sec, 3 : 8 sec
146 */
147 if (parm->interval < -2 || parm->interval > 3)
148 return -EINVAL;
149
150 est = kzalloc(sizeof(*est), GFP_KERNEL);
151 if (!est)
152 return -ENOBUFS;
153
154 seqcount_init(&est->seq);
155 intvl_log = parm->interval + 2;
156 est->bstats = bstats;
157 est->stats_lock = stats_lock;
158 est->running = running;
159 est->ewma_log = parm->ewma_log;
160 est->intvl_log = intvl_log;
161 est->cpu_bstats = cpu_bstats;
162
163 if (stats_lock)
164 local_bh_disable();
165 est_fetch_counters(est, &b);
166 if (stats_lock)
167 local_bh_enable();
168 est->last_bytes = b.bytes;
169 est->last_packets = b.packets;
170 old = rcu_dereference_protected(*rate_est, 1);
171 if (old) {
172 del_timer_sync(&old->timer);
173 est->avbps = old->avbps;
174 est->avpps = old->avpps;
175 }
176
177 est->next_jiffies = jiffies + ((HZ/4) << intvl_log);
178 timer_setup(&est->timer, est_timer, 0);
179 mod_timer(&est->timer, est->next_jiffies);
180
181 rcu_assign_pointer(*rate_est, est);
182 if (old)
183 kfree_rcu(old, rcu);
184 return 0;
185}
186EXPORT_SYMBOL(gen_new_estimator);
187
188/**
189 * gen_kill_estimator - remove a rate estimator
190 * @rate_est: rate estimator
191 *
192 * Removes the rate estimator.
193 *
194 */
195void gen_kill_estimator(struct net_rate_estimator __rcu **rate_est)
196{
197 struct net_rate_estimator *est;
198
199 est = xchg((__force struct net_rate_estimator **)rate_est, NULL);
200 if (est) {
201 del_timer_sync(&est->timer);
202 kfree_rcu(est, rcu);
203 }
204}
205EXPORT_SYMBOL(gen_kill_estimator);
206
207/**
208 * gen_replace_estimator - replace rate estimator configuration
209 * @bstats: basic statistics
210 * @cpu_bstats: bstats per cpu
211 * @rate_est: rate estimator statistics
212 * @stats_lock: statistics lock
213 * @running: qdisc running seqcount (might be NULL)
214 * @opt: rate estimator configuration TLV
215 *
216 * Replaces the configuration of a rate estimator by calling
217 * gen_kill_estimator() and gen_new_estimator().
218 *
219 * Returns 0 on success or a negative error code.
220 */
221int gen_replace_estimator(struct gnet_stats_basic_packed *bstats,
222 struct gnet_stats_basic_cpu __percpu *cpu_bstats,
223 struct net_rate_estimator __rcu **rate_est,
224 spinlock_t *stats_lock,
225 seqcount_t *running, struct nlattr *opt)
226{
227 return gen_new_estimator(bstats, cpu_bstats, rate_est,
228 stats_lock, running, opt);
229}
230EXPORT_SYMBOL(gen_replace_estimator);
231
232/**
233 * gen_estimator_active - test if estimator is currently in use
234 * @rate_est: rate estimator
235 *
236 * Returns true if estimator is active, and false if not.
237 */
238bool gen_estimator_active(struct net_rate_estimator __rcu **rate_est)
239{
240 return !!rcu_access_pointer(*rate_est);
241}
242EXPORT_SYMBOL(gen_estimator_active);
243
244bool gen_estimator_read(struct net_rate_estimator __rcu **rate_est,
245 struct gnet_stats_rate_est64 *sample)
246{
247 struct net_rate_estimator *est;
248 unsigned seq;
249
250 rcu_read_lock();
251 est = rcu_dereference(*rate_est);
252 if (!est) {
253 rcu_read_unlock();
254 return false;
255 }
256
257 do {
258 seq = read_seqcount_begin(&est->seq);
259 sample->bps = est->avbps >> 8;
260 sample->pps = est->avpps >> 8;
261 } while (read_seqcount_retry(&est->seq, seq));
262
263 rcu_read_unlock();
264 return true;
265}
266EXPORT_SYMBOL(gen_estimator_read);