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git.proxmox.com Git - mirror_ubuntu-bionic-kernel.git/blob - net/core/gen_estimator.c
2 * net/sched/gen_estimator.c Simple rate estimator.
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.
9 * Authors: Alexey Kuznetsov, <kuznet@ms2.inr.ac.ru>
12 * Jamal Hadi Salim - moved it to net/core and reshulfed
13 * names to make it usable in general net subsystem.
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>
24 #include <linux/socket.h>
25 #include <linux/sockios.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>
36 #include <net/gen_stats.h>
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.
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)
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.
56 We measure rate over A=(1<<interval) seconds and evaluate EWMA:
58 avrate = avrate*(1-W) + rate*W
60 where W is chosen as negative power of 2: W = 2^(-ewma_log)
62 The resulting time constant is:
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.
79 #define EST_MAX_INTERVAL 5
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
;
92 struct rcu_head e_rcu
;
96 struct gen_estimator_head
98 struct timer_list timer
;
99 struct list_head list
;
102 static struct gen_estimator_head elist
[EST_MAX_INTERVAL
+1];
104 /* Protects against NULL dereference */
105 static DEFINE_RWLOCK(est_lock
);
107 /* Protects against soft lockup during large deletion */
108 static struct rb_root est_root
= RB_ROOT
;
109 static DEFINE_SPINLOCK(est_tree_lock
);
111 static void est_timer(unsigned long arg
)
114 struct gen_estimator
*e
;
117 list_for_each_entry_rcu(e
, &elist
[idx
].list
, list
) {
123 spin_lock(e
->stats_lock
);
124 read_lock(&est_lock
);
125 if (e
->bstats
== NULL
)
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;
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;
140 read_unlock(&est_lock
);
141 spin_unlock(e
->stats_lock
);
144 if (!list_empty(&elist
[idx
].list
))
145 mod_timer(&elist
[idx
].timer
, jiffies
+ ((HZ
/4) << idx
));
149 static void gen_add_node(struct gen_estimator
*est
)
151 struct rb_node
**p
= &est_root
.rb_node
, *parent
= NULL
;
154 struct gen_estimator
*e
;
157 e
= rb_entry(parent
, struct gen_estimator
, node
);
159 if (est
->bstats
> e
->bstats
)
160 p
= &parent
->rb_right
;
162 p
= &parent
->rb_left
;
164 rb_link_node(&est
->node
, parent
, p
);
165 rb_insert_color(&est
->node
, &est_root
);
169 struct gen_estimator
*gen_find_node(const struct gnet_stats_basic_packed
*bstats
,
170 const struct gnet_stats_rate_est
*rate_est
)
172 struct rb_node
*p
= est_root
.rb_node
;
175 struct gen_estimator
*e
;
177 e
= rb_entry(p
, struct gen_estimator
, node
);
179 if (bstats
> e
->bstats
)
181 else if (bstats
< e
->bstats
|| rate_est
!= e
->rate_est
)
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
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.
202 * Returns 0 on success or a negative error code.
205 int gen_new_estimator(struct gnet_stats_basic_packed
*bstats
,
206 struct gnet_stats_rate_est
*rate_est
,
207 spinlock_t
*stats_lock
,
210 struct gen_estimator
*est
;
211 struct gnet_estimator
*parm
= nla_data(opt
);
214 if (nla_len(opt
) < sizeof(*parm
))
217 if (parm
->interval
< -2 || parm
->interval
> 3)
220 est
= kzalloc(sizeof(*est
), GFP_KERNEL
);
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;
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
);
240 if (list_empty(&elist
[idx
].list
))
241 mod_timer(&elist
[idx
].timer
, jiffies
+ ((HZ
/4) << idx
));
243 list_add_rcu(&est
->list
, &elist
[idx
].list
);
245 spin_unlock_bh(&est_tree_lock
);
249 EXPORT_SYMBOL(gen_new_estimator
);
252 * gen_kill_estimator - remove a rate estimator
253 * @bstats: basic statistics
254 * @rate_est: rate estimator statistics
256 * Removes the rate estimator specified by &bstats and &rate_est.
258 * Note : Caller should respect an RCU grace period before freeing stats_lock
260 void gen_kill_estimator(struct gnet_stats_basic_packed
*bstats
,
261 struct gnet_stats_rate_est
*rate_est
)
263 struct gen_estimator
*e
;
265 spin_lock_bh(&est_tree_lock
);
266 while ((e
= gen_find_node(bstats
, rate_est
))) {
267 rb_erase(&e
->node
, &est_root
);
269 write_lock(&est_lock
);
271 write_unlock(&est_lock
);
273 list_del_rcu(&e
->list
);
276 spin_unlock_bh(&est_tree_lock
);
278 EXPORT_SYMBOL(gen_kill_estimator
);
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
287 * Replaces the configuration of a rate estimator by calling
288 * gen_kill_estimator() and gen_new_estimator().
290 * Returns 0 on success or a negative error code.
292 int 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
)
296 gen_kill_estimator(bstats
, rate_est
);
297 return gen_new_estimator(bstats
, rate_est
, stats_lock
, opt
);
299 EXPORT_SYMBOL(gen_replace_estimator
);
302 * gen_estimator_active - test if estimator is currently in use
303 * @bstats: basic statistics
304 * @rate_est: rate estimator statistics
306 * Returns true if estimator is active, and false if not.
308 bool gen_estimator_active(const struct gnet_stats_basic_packed
*bstats
,
309 const struct gnet_stats_rate_est
*rate_est
)
315 spin_lock_bh(&est_tree_lock
);
316 res
= gen_find_node(bstats
, rate_est
) != NULL
;
317 spin_unlock_bh(&est_tree_lock
);
321 EXPORT_SYMBOL(gen_estimator_active
);