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