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 46 struct 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 66 static 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 80 static 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 * @lock: lock for statistics and control path 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 */ 128 int 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 *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 = 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 (lock) 164 local_bh_disable(); 165 est_fetch_counters(est, &b); 166 if (lock) 167 local_bh_enable(); 168 est->last_bytes = b.bytes; 169 est->last_packets = b.packets; 170 171 if (lock) 172 spin_lock_bh(lock); 173 old = rcu_dereference_protected(*rate_est, 1); 174 if (old) { 175 del_timer_sync(&old->timer); 176 est->avbps = old->avbps; 177 est->avpps = old->avpps; 178 } 179 180 est->next_jiffies = jiffies + ((HZ/4) << intvl_log); 181 timer_setup(&est->timer, est_timer, 0); 182 mod_timer(&est->timer, est->next_jiffies); 183 184 rcu_assign_pointer(*rate_est, est); 185 if (lock) 186 spin_unlock_bh(lock); 187 if (old) 188 kfree_rcu(old, rcu); 189 return 0; 190 } 191 EXPORT_SYMBOL(gen_new_estimator); 192 193 /** 194 * gen_kill_estimator - remove a rate estimator 195 * @rate_est: rate estimator 196 * 197 * Removes the rate estimator. 198 * 199 */ 200 void gen_kill_estimator(struct net_rate_estimator __rcu **rate_est) 201 { 202 struct net_rate_estimator *est; 203 204 est = xchg((__force struct net_rate_estimator **)rate_est, NULL); 205 if (est) { 206 del_timer_sync(&est->timer); 207 kfree_rcu(est, rcu); 208 } 209 } 210 EXPORT_SYMBOL(gen_kill_estimator); 211 212 /** 213 * gen_replace_estimator - replace rate estimator configuration 214 * @bstats: basic statistics 215 * @cpu_bstats: bstats per cpu 216 * @rate_est: rate estimator statistics 217 * @lock: lock for statistics and control path 218 * @running: qdisc running seqcount (might be NULL) 219 * @opt: rate estimator configuration TLV 220 * 221 * Replaces the configuration of a rate estimator by calling 222 * gen_kill_estimator() and gen_new_estimator(). 223 * 224 * Returns 0 on success or a negative error code. 225 */ 226 int gen_replace_estimator(struct gnet_stats_basic_packed *bstats, 227 struct gnet_stats_basic_cpu __percpu *cpu_bstats, 228 struct net_rate_estimator __rcu **rate_est, 229 spinlock_t *lock, 230 seqcount_t *running, struct nlattr *opt) 231 { 232 return gen_new_estimator(bstats, cpu_bstats, rate_est, 233 lock, running, opt); 234 } 235 EXPORT_SYMBOL(gen_replace_estimator); 236 237 /** 238 * gen_estimator_active - test if estimator is currently in use 239 * @rate_est: rate estimator 240 * 241 * Returns true if estimator is active, and false if not. 242 */ 243 bool gen_estimator_active(struct net_rate_estimator __rcu **rate_est) 244 { 245 return !!rcu_access_pointer(*rate_est); 246 } 247 EXPORT_SYMBOL(gen_estimator_active); 248 249 bool gen_estimator_read(struct net_rate_estimator __rcu **rate_est, 250 struct gnet_stats_rate_est64 *sample) 251 { 252 struct net_rate_estimator *est; 253 unsigned seq; 254 255 rcu_read_lock(); 256 est = rcu_dereference(*rate_est); 257 if (!est) { 258 rcu_read_unlock(); 259 return false; 260 } 261 262 do { 263 seq = read_seqcount_begin(&est->seq); 264 sample->bps = est->avbps >> 8; 265 sample->pps = est->avpps >> 8; 266 } while (read_seqcount_retry(&est->seq, seq)); 267 268 rcu_read_unlock(); 269 return true; 270 } 271 EXPORT_SYMBOL(gen_estimator_read); 272