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Diffstat (limited to 'net/core/gen_estimator.c')
| -rw-r--r-- | net/core/gen_estimator.c | 250 |
1 files changed, 250 insertions, 0 deletions
diff --git a/net/core/gen_estimator.c b/net/core/gen_estimator.c new file mode 100644 index 000000000000..b07c029e8219 --- /dev/null +++ b/net/core/gen_estimator.c @@ -0,0 +1,250 @@ +/* + * net/sched/gen_estimator.c Simple rate estimator. + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public License + * as published by the Free Software Foundation; either version + * 2 of the License, or (at your option) any later version. + * + * Authors: Alexey Kuznetsov, <kuznet@ms2.inr.ac.ru> + * + * Changes: + * Jamal Hadi Salim - moved it to net/core and reshulfed + * names to make it usable in general net subsystem. + */ + +#include <asm/uaccess.h> +#include <asm/system.h> +#include <asm/bitops.h> +#include <linux/module.h> +#include <linux/types.h> +#include <linux/kernel.h> +#include <linux/jiffies.h> +#include <linux/string.h> +#include <linux/mm.h> +#include <linux/socket.h> +#include <linux/sockios.h> +#include <linux/in.h> +#include <linux/errno.h> +#include <linux/interrupt.h> +#include <linux/netdevice.h> +#include <linux/skbuff.h> +#include <linux/rtnetlink.h> +#include <linux/init.h> +#include <net/sock.h> +#include <net/gen_stats.h> + +/* + This code is NOT intended to be used for statistics collection, + its purpose is to provide a base for statistical multiplexing + for controlled load service. + If you need only statistics, run a user level daemon which + periodically reads byte counters. + + Unfortunately, rate estimation is not a very easy task. + F.e. I did not find a simple way to estimate the current peak rate + and even failed to formulate the problem 8)8) + + So I preferred not to built an estimator into the scheduler, + but run this task separately. + Ideally, it should be kernel thread(s), but for now it runs + from timers, which puts apparent top bounds on the number of rated + flows, has minimal overhead on small, but is enough + to handle controlled load service, sets of aggregates. + + We measure rate over A=(1<<interval) seconds and evaluate EWMA: + + avrate = avrate*(1-W) + rate*W + + where W is chosen as negative power of 2: W = 2^(-ewma_log) + + The resulting time constant is: + + T = A/(-ln(1-W)) + + + NOTES. + + * The stored value for avbps is scaled by 2^5, so that maximal + rate is ~1Gbit, avpps is scaled by 2^10. + + * Minimal interval is HZ/4=250msec (it is the greatest common divisor + for HZ=100 and HZ=1024 8)), maximal interval + is (HZ*2^EST_MAX_INTERVAL)/4 = 8sec. Shorter intervals + are too expensive, longer ones can be implemented + at user level painlessly. + */ + +#define EST_MAX_INTERVAL 5 + +struct gen_estimator +{ + struct gen_estimator *next; + struct gnet_stats_basic *bstats; + struct gnet_stats_rate_est *rate_est; + spinlock_t *stats_lock; + unsigned interval; + int ewma_log; + u64 last_bytes; + u32 last_packets; + u32 avpps; + u32 avbps; +}; + +struct gen_estimator_head +{ + struct timer_list timer; + struct gen_estimator *list; +}; + +static struct gen_estimator_head elist[EST_MAX_INTERVAL+1]; + +/* Estimator array lock */ +static DEFINE_RWLOCK(est_lock); + +static void est_timer(unsigned long arg) +{ + int idx = (int)arg; + struct gen_estimator *e; + + read_lock(&est_lock); + for (e = elist[idx].list; e; e = e->next) { + u64 nbytes; + u32 npackets; + u32 rate; + + spin_lock(e->stats_lock); + nbytes = e->bstats->bytes; + npackets = e->bstats->packets; + rate = (nbytes - e->last_bytes)<<(7 - idx); + e->last_bytes = nbytes; + e->avbps += ((long)rate - (long)e->avbps) >> e->ewma_log; + e->rate_est->bps = (e->avbps+0xF)>>5; + + rate = (npackets - e->last_packets)<<(12 - idx); + e->last_packets = npackets; + e->avpps += ((long)rate - (long)e->avpps) >> e->ewma_log; + e->rate_est->pps = (e->avpps+0x1FF)>>10; + spin_unlock(e->stats_lock); + } + + mod_timer(&elist[idx].timer, jiffies + ((HZ<<idx)/4)); + read_unlock(&est_lock); +} + +/** + * gen_new_estimator - create a new rate estimator + * @bstats: basic statistics + * @rate_est: rate estimator statistics + * @stats_lock: statistics lock + * @opt: rate estimator configuration TLV + * + * Creates a new rate estimator with &bstats as source and &rate_est + * as destination. A new timer with the interval specified in the + * configuration TLV is created. Upon each interval, the latest statistics + * will be read from &bstats and the estimated rate will be stored in + * &rate_est with the statistics lock grabed during this period. + * + * Returns 0 on success or a negative error code. + */ +int gen_new_estimator(struct gnet_stats_basic *bstats, + struct gnet_stats_rate_est *rate_est, spinlock_t *stats_lock, struct rtattr *opt) +{ + struct gen_estimator *est; + struct gnet_estimator *parm = RTA_DATA(opt); + + if (RTA_PAYLOAD(opt) < sizeof(*parm)) + return -EINVAL; + + if (parm->interval < -2 || parm->interval > 3) + return -EINVAL; + + est = kmalloc(sizeof(*est), GFP_KERNEL); + if (est == NULL) + return -ENOBUFS; + + memset(est, 0, sizeof(*est)); + est->interval = parm->interval + 2; + est->bstats = bstats; + est->rate_est = rate_est; + est->stats_lock = stats_lock; + est->ewma_log = parm->ewma_log; + est->last_bytes = bstats->bytes; + est->avbps = rate_est->bps<<5; + est->last_packets = bstats->packets; + est->avpps = rate_est->pps<<10; + + est->next = elist[est->interval].list; + if (est->next == NULL) { + init_timer(&elist[est->interval].timer); + elist[est->interval].timer.data = est->interval; + elist[est->interval].timer.expires = jiffies + ((HZ<<est->interval)/4); + elist[est->interval].timer.function = est_timer; + add_timer(&elist[est->interval].timer); + } + write_lock_bh(&est_lock); + elist[est->interval].list = est; + write_unlock_bh(&est_lock); + return 0; +} + +/** + * gen_kill_estimator - remove a rate estimator + * @bstats: basic statistics + * @rate_est: rate estimator statistics + * + * Removes the rate estimator specified by &bstats and &rate_est + * and deletes the timer. + */ +void gen_kill_estimator(struct gnet_stats_basic *bstats, + struct gnet_stats_rate_est *rate_est) +{ + int idx; + struct gen_estimator *est, **pest; + + for (idx=0; idx <= EST_MAX_INTERVAL; idx++) { + int killed = 0; + pest = &elist[idx].list; + while ((est=*pest) != NULL) { + if (est->rate_est != rate_est || est->bstats != bstats) { + pest = &est->next; + continue; + } + + write_lock_bh(&est_lock); + *pest = est->next; + write_unlock_bh(&est_lock); + + kfree(est); + killed++; + } + if (killed && elist[idx].list == NULL) + del_timer(&elist[idx].timer); + } +} + +/** + * gen_replace_estimator - replace rate estimator configruation + * @bstats: basic statistics + * @rate_est: rate estimator statistics + * @stats_lock: statistics lock + * @opt: rate estimator configuration TLV + * + * Replaces the configuration of a rate estimator by calling + * gen_kill_estimator() and gen_new_estimator(). + * + * Returns 0 on success or a negative error code. + */ +int +gen_replace_estimator(struct gnet_stats_basic *bstats, + struct gnet_stats_rate_est *rate_est, spinlock_t *stats_lock, + struct rtattr *opt) +{ + gen_kill_estimator(bstats, rate_est); + return gen_new_estimator(bstats, rate_est, stats_lock, opt); +} + + +EXPORT_SYMBOL(gen_kill_estimator); +EXPORT_SYMBOL(gen_new_estimator); +EXPORT_SYMBOL(gen_replace_estimator); |