diff options
Diffstat (limited to 'net/sched/estimator.c')
| -rw-r--r-- | net/sched/estimator.c | 197 |
1 files changed, 197 insertions, 0 deletions
diff --git a/net/sched/estimator.c b/net/sched/estimator.c new file mode 100644 index 000000000000..5d3ae03e22a7 --- /dev/null +++ b/net/sched/estimator.c @@ -0,0 +1,197 @@ +/* + * net/sched/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> + */ + +#include <asm/uaccess.h> +#include <asm/system.h> +#include <linux/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/pkt_sched.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 qdisc_estimator +{ + struct qdisc_estimator *next; + struct tc_stats *stats; + spinlock_t *stats_lock; + unsigned interval; + int ewma_log; + u64 last_bytes; + u32 last_packets; + u32 avpps; + u32 avbps; +}; + +struct qdisc_estimator_head +{ + struct timer_list timer; + struct qdisc_estimator *list; +}; + +static struct qdisc_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 qdisc_estimator *e; + + read_lock(&est_lock); + for (e = elist[idx].list; e; e = e->next) { + struct tc_stats *st = e->stats; + u64 nbytes; + u32 npackets; + u32 rate; + + spin_lock(e->stats_lock); + nbytes = st->bytes; + npackets = st->packets; + rate = (nbytes - e->last_bytes)<<(7 - idx); + e->last_bytes = nbytes; + e->avbps += ((long)rate - (long)e->avbps) >> e->ewma_log; + st->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->stats->pps = (e->avpps+0x1FF)>>10; + spin_unlock(e->stats_lock); + } + + mod_timer(&elist[idx].timer, jiffies + ((HZ<<idx)/4)); + read_unlock(&est_lock); +} + +int qdisc_new_estimator(struct tc_stats *stats, spinlock_t *stats_lock, struct rtattr *opt) +{ + struct qdisc_estimator *est; + struct tc_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->stats = stats; + est->stats_lock = stats_lock; + est->ewma_log = parm->ewma_log; + est->last_bytes = stats->bytes; + est->avbps = stats->bps<<5; + est->last_packets = stats->packets; + est->avpps = stats->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; +} + +void qdisc_kill_estimator(struct tc_stats *stats) +{ + int idx; + struct qdisc_estimator *est, **pest; + + for (idx=0; idx <= EST_MAX_INTERVAL; idx++) { + int killed = 0; + pest = &elist[idx].list; + while ((est=*pest) != NULL) { + if (est->stats != stats) { + 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); + } +} + +EXPORT_SYMBOL(qdisc_kill_estimator); +EXPORT_SYMBOL(qdisc_new_estimator); |