1 // SPDX-License-Identifier: GPL-2.0-or-later
3 * net/sched/gen_estimator.c Simple rate estimator.
5 * Authors: Alexey Kuznetsov, <kuznet@ms2.inr.ac.ru>
6 * Eric Dumazet <edumazet@google.com>
9 * Jamal Hadi Salim - moved it to net/core and reshulfed
10 * names to make it usable in general net subsystem.
13 #include <linux/uaccess.h>
14 #include <linux/bitops.h>
15 #include <linux/module.h>
16 #include <linux/types.h>
17 #include <linux/kernel.h>
18 #include <linux/jiffies.h>
19 #include <linux/string.h>
21 #include <linux/socket.h>
22 #include <linux/sockios.h>
24 #include <linux/errno.h>
25 #include <linux/interrupt.h>
26 #include <linux/netdevice.h>
27 #include <linux/skbuff.h>
28 #include <linux/rtnetlink.h>
29 #include <linux/init.h>
30 #include <linux/slab.h>
31 #include <linux/seqlock.h>
33 #include <net/gen_stats.h>
35 /* This code is NOT intended to be used for statistics collection,
36 * its purpose is to provide a base for statistical multiplexing
37 * for controlled load service.
38 * If you need only statistics, run a user level daemon which
39 * periodically reads byte counters.
42 struct net_rate_estimator {
43 struct gnet_stats_basic_sync *bstats;
44 spinlock_t *stats_lock;
46 struct gnet_stats_basic_sync __percpu *cpu_bstats;
48 u8 intvl_log; /* period : (250ms << intvl_log) */
57 unsigned long next_jiffies;
58 struct timer_list timer;
62 static void est_fetch_counters(struct net_rate_estimator *e,
63 struct gnet_stats_basic_sync *b)
65 gnet_stats_basic_sync_init(b);
67 spin_lock(e->stats_lock);
69 gnet_stats_add_basic(b, e->cpu_bstats, e->bstats, e->running);
72 spin_unlock(e->stats_lock);
76 static void est_timer(struct timer_list *t)
78 struct net_rate_estimator *est = from_timer(est, t, timer);
79 struct gnet_stats_basic_sync b;
80 u64 b_bytes, b_packets;
83 est_fetch_counters(est, &b);
84 b_bytes = u64_stats_read(&b.bytes);
85 b_packets = u64_stats_read(&b.packets);
87 brate = (b_bytes - est->last_bytes) << (10 - est->intvl_log);
88 brate = (brate >> est->ewma_log) - (est->avbps >> est->ewma_log);
90 rate = (b_packets - est->last_packets) << (10 - est->intvl_log);
91 rate = (rate >> est->ewma_log) - (est->avpps >> est->ewma_log);
93 write_seqcount_begin(&est->seq);
96 write_seqcount_end(&est->seq);
98 est->last_bytes = b_bytes;
99 est->last_packets = b_packets;
101 est->next_jiffies += ((HZ/4) << est->intvl_log);
103 if (unlikely(time_after_eq(jiffies, est->next_jiffies))) {
104 /* Ouch... timer was delayed. */
105 est->next_jiffies = jiffies + 1;
107 mod_timer(&est->timer, est->next_jiffies);
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 * @lock: lock for statistics and control path
116 * @running: true if @bstats represents a running qdisc, thus @bstats'
117 * internal values might change during basic reads. Only used
118 * if @bstats_cpu is NULL
119 * @opt: rate estimator configuration TLV
121 * Creates a new rate estimator with &bstats as source and &rate_est
122 * as destination. A new timer with the interval specified in the
123 * configuration TLV is created. Upon each interval, the latest statistics
124 * will be read from &bstats and the estimated rate will be stored in
125 * &rate_est with the statistics lock grabbed during this period.
127 * Returns 0 on success or a negative error code.
130 int gen_new_estimator(struct gnet_stats_basic_sync *bstats,
131 struct gnet_stats_basic_sync __percpu *cpu_bstats,
132 struct net_rate_estimator __rcu **rate_est,
137 struct gnet_estimator *parm = nla_data(opt);
138 struct net_rate_estimator *old, *est;
139 struct gnet_stats_basic_sync b;
142 if (nla_len(opt) < sizeof(*parm))
145 /* allowed timer periods are :
146 * -2 : 250ms, -1 : 500ms, 0 : 1 sec
147 * 1 : 2 sec, 2 : 4 sec, 3 : 8 sec
149 if (parm->interval < -2 || parm->interval > 3)
152 if (parm->ewma_log == 0 || parm->ewma_log >= 31)
155 est = kzalloc(sizeof(*est), GFP_KERNEL);
159 seqcount_init(&est->seq);
160 intvl_log = parm->interval + 2;
161 est->bstats = bstats;
162 est->stats_lock = lock;
163 est->running = running;
164 est->ewma_log = parm->ewma_log;
165 est->intvl_log = intvl_log;
166 est->cpu_bstats = cpu_bstats;
170 est_fetch_counters(est, &b);
173 est->last_bytes = u64_stats_read(&b.bytes);
174 est->last_packets = u64_stats_read(&b.packets);
178 old = rcu_dereference_protected(*rate_est, 1);
180 del_timer_sync(&old->timer);
181 est->avbps = old->avbps;
182 est->avpps = old->avpps;
185 est->next_jiffies = jiffies + ((HZ/4) << intvl_log);
186 timer_setup(&est->timer, est_timer, 0);
187 mod_timer(&est->timer, est->next_jiffies);
189 rcu_assign_pointer(*rate_est, est);
191 spin_unlock_bh(lock);
196 EXPORT_SYMBOL(gen_new_estimator);
199 * gen_kill_estimator - remove a rate estimator
200 * @rate_est: rate estimator
202 * Removes the rate estimator.
205 void gen_kill_estimator(struct net_rate_estimator __rcu **rate_est)
207 struct net_rate_estimator *est;
209 est = xchg((__force struct net_rate_estimator **)rate_est, NULL);
211 del_timer_sync(&est->timer);
215 EXPORT_SYMBOL(gen_kill_estimator);
218 * gen_replace_estimator - replace rate estimator configuration
219 * @bstats: basic statistics
220 * @cpu_bstats: bstats per cpu
221 * @rate_est: rate estimator statistics
222 * @lock: lock for statistics and control path
223 * @running: true if @bstats represents a running qdisc, thus @bstats'
224 * internal values might change during basic reads. Only used
225 * if @cpu_bstats is NULL
226 * @opt: rate estimator configuration TLV
228 * Replaces the configuration of a rate estimator by calling
229 * gen_kill_estimator() and gen_new_estimator().
231 * Returns 0 on success or a negative error code.
233 int gen_replace_estimator(struct gnet_stats_basic_sync *bstats,
234 struct gnet_stats_basic_sync __percpu *cpu_bstats,
235 struct net_rate_estimator __rcu **rate_est,
237 bool running, struct nlattr *opt)
239 return gen_new_estimator(bstats, cpu_bstats, rate_est,
242 EXPORT_SYMBOL(gen_replace_estimator);
245 * gen_estimator_active - test if estimator is currently in use
246 * @rate_est: rate estimator
248 * Returns true if estimator is active, and false if not.
250 bool gen_estimator_active(struct net_rate_estimator __rcu **rate_est)
252 return !!rcu_access_pointer(*rate_est);
254 EXPORT_SYMBOL(gen_estimator_active);
256 bool gen_estimator_read(struct net_rate_estimator __rcu **rate_est,
257 struct gnet_stats_rate_est64 *sample)
259 struct net_rate_estimator *est;
263 est = rcu_dereference(*rate_est);
270 seq = read_seqcount_begin(&est->seq);
271 sample->bps = est->avbps >> 8;
272 sample->pps = est->avpps >> 8;
273 } while (read_seqcount_retry(&est->seq, seq));
278 EXPORT_SYMBOL(gen_estimator_read);