LXR linux/net/core/gen

   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
  46struct 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
  66static 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
  79static 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 */
 127int 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}
 181EXPORT_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 */
 190void 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}
 200EXPORT_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 */
 216int 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}
 225EXPORT_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 */
 233bool gen_estimator_active(struct net_rate_estimator __rcu **rate_est)
 234{
 235        return !!rcu_access_pointer(*rate_est);
 236}
 237EXPORT_SYMBOL(gen_estimator_active);
 238
 239bool 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}
 261EXPORT_SYMBOL(gen_estimator_read);
 262