net/core/gen_estimator.c

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