1 // SPDX-License-Identifier: GPL-2.0-or-later 2 /* 3 * net/sched/gen_estimator.c Simple rate estimator. 4 * 5 * Authors: Alexey Kuznetsov, <kuznet@ms2.inr.ac.ru> 6 * Eric Dumazet <edumazet@google.com> 7 * 8 * Changes: 9 * Jamal Hadi Salim - moved it to net/core and reshulfed 10 * names to make it usable in general net subsystem. 11 */ 12 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> 20 #include <linux/mm.h> 21 #include <linux/socket.h> 22 #include <linux/sockios.h> 23 #include <linux/in.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> 32 #include <net/sock.h> 33 #include <net/gen_stats.h> 34 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. 40 */ 41 42 struct net_rate_estimator { 43 struct gnet_stats_basic_sync *bstats; 44 spinlock_t *stats_lock; 45 bool running; 46 struct gnet_stats_basic_sync __percpu *cpu_bstats; 47 u8 ewma_log; 48 u8 intvl_log; /* period : (250ms << intvl_log) */ 49 50 seqcount_t seq; 51 u64 last_packets; 52 u64 last_bytes; 53 54 u64 avpps; 55 u64 avbps; 56 57 unsigned long next_jiffies; 58 struct timer_list timer; 59 struct rcu_head rcu; 60 }; 61 62 static void est_fetch_counters(struct net_rate_estimator *e, 63 struct gnet_stats_basic_sync *b) 64 { 65 gnet_stats_basic_sync_init(b); 66 if (e->stats_lock) 67 spin_lock(e->stats_lock); 68 69 gnet_stats_add_basic(b, e->cpu_bstats, e->bstats, e->running); 70 71 if (e->stats_lock) 72 spin_unlock(e->stats_lock); 73 74 } 75 76 static void est_timer(struct timer_list *t) 77 { 78 struct net_rate_estimator *est = from_timer(est, t, timer); 79 struct gnet_stats_basic_sync b; 80 u64 b_bytes, b_packets; 81 u64 rate, brate; 82 83 est_fetch_counters(est, &b); 84 b_bytes = u64_stats_read(&b.bytes); 85 b_packets = u64_stats_read(&b.packets); 86 87 brate = (b_bytes - est->last_bytes) << (10 - est->intvl_log); 88 brate = (brate >> est->ewma_log) - (est->avbps >> est->ewma_log); 89 90 rate = (b_packets - est->last_packets) << (10 - est->intvl_log); 91 rate = (rate >> est->ewma_log) - (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: 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 120 * 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. 126 * 127 * Returns 0 on success or a negative error code. 128 * 129 */ 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, 133 spinlock_t *lock, 134 bool running, 135 struct nlattr *opt) 136 { 137 struct gnet_estimator *parm = nla_data(opt); 138 struct net_rate_estimator *old, *est; 139 struct gnet_stats_basic_sync b; 140 int intvl_log; 141 142 if (nla_len(opt) < sizeof(*parm)) 143 return -EINVAL; 144 145 /* allowed timer periods are : 146 * -2 : 250ms, -1 : 500ms, 0 : 1 sec 147 * 1 : 2 sec, 2 : 4 sec, 3 : 8 sec 148 */ 149 if (parm->interval < -2 || parm->interval > 3) 150 return -EINVAL; 151 152 if (parm->ewma_log == 0 || parm->ewma_log >= 31) 153 return -EINVAL; 154 155 est = kzalloc(sizeof(*est), GFP_KERNEL); 156 if (!est) 157 return -ENOBUFS; 158 159 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; 167 168 if (lock) 169 local_bh_disable(); 170 est_fetch_counters(est, &b); 171 if (lock) 172 local_bh_enable(); 173 est->last_bytes = u64_stats_read(&b.bytes); 174 est->last_packets = u64_stats_read(&b.packets); 175 176 if (lock) 177 spin_lock_bh(lock); 178 old = rcu_dereference_protected(*rate_est, 1); 179 if (old) { 180 del_timer_sync(&old->timer); 181 est->avbps = old->avbps; 182 est->avpps = old->avpps; 183 } 184 185 est->next_jiffies = jiffies + ((HZ/4) << intvl_log); 186 timer_setup(&est->timer, est_timer, 0); 187 mod_timer(&est->timer, est->next_jiffies); 188 189 rcu_assign_pointer(*rate_est, est); 190 if (lock) 191 spin_unlock_bh(lock); 192 if (old) 193 kfree_rcu(old, rcu); 194 return 0; 195 } 196 EXPORT_SYMBOL(gen_new_estimator); 197 198 /** 199 * gen_kill_estimator - remove a rate estimator 200 * @rate_est: rate estimator 201 * 202 * Removes the rate estimator. 203 * 204 */ 205 void gen_kill_estimator(struct net_rate_estimator __rcu **rate_est) 206 { 207 struct net_rate_estimator *est; 208 209 est = xchg((__force struct net_rate_estimator **)rate_est, NULL); 210 if (est) { 211 timer_shutdown_sync(&est->timer); 212 kfree_rcu(est, rcu); 213 } 214 } 215 EXPORT_SYMBOL(gen_kill_estimator); 216 217 /** 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 227 * 228 * Replaces the configuration of a rate estimator by calling 229 * gen_kill_estimator() and gen_new_estimator(). 230 * 231 * Returns 0 on success or a negative error code. 232 */ 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, 236 spinlock_t *lock, 237 bool running, struct nlattr *opt) 238 { 239 return gen_new_estimator(bstats, cpu_bstats, rate_est, 240 lock, running, opt); 241 } 242 EXPORT_SYMBOL(gen_replace_estimator); 243 244 /** 245 * gen_estimator_active - test if estimator is currently in use 246 * @rate_est: rate estimator 247 * 248 * Returns true if estimator is active, and false if not. 249 */ 250 bool gen_estimator_active(struct net_rate_estimator __rcu **rate_est) 251 { 252 return !!rcu_access_pointer(*rate_est); 253 } 254 EXPORT_SYMBOL(gen_estimator_active); 255 256 bool gen_estimator_read(struct net_rate_estimator __rcu **rate_est, 257 struct gnet_stats_rate_est64 *sample) 258 { 259 struct net_rate_estimator *est; 260 unsigned seq; 261 262 rcu_read_lock(); 263 est = rcu_dereference(*rate_est); 264 if (!est) { 265 rcu_read_unlock(); 266 return false; 267 } 268 269 do { 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)); 274 275 rcu_read_unlock(); 276 return true; 277 } 278 EXPORT_SYMBOL(gen_estimator_read); 279