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         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) << (10 - est->ewma_log - est->intvl_log);
  87         brate -= (est->avbps >> est->ewma_log);
  88
  89         rate = (u64)(b.packets - est->last_packets) << (10 - est->ewma_log - est->intvl_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);