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![David Howells](/assets/img/avatar_default.png)
Remove all #inclusions of asm/system.h preparatory to splitting and killing it. Performed with the following command: perl -p -i -e 's!^#\s*include\s*<asm/system[.]h>.*\n!!' `grep -Irl '^#\s*include\s*<asm/system[.]h>' *` Signed-off-by: David Howells <dhowells@redhat.com>
321 lines
8.4 KiB
C
321 lines
8.4 KiB
C
/*
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* net/sched/gen_estimator.c Simple rate estimator.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version
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* 2 of the License, or (at your option) any later version.
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*
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* Authors: Alexey Kuznetsov, <kuznet@ms2.inr.ac.ru>
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*
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* Changes:
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* Jamal Hadi Salim - moved it to net/core and reshulfed
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* names to make it usable in general net subsystem.
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*/
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#include <asm/uaccess.h>
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#include <linux/bitops.h>
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#include <linux/module.h>
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#include <linux/types.h>
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#include <linux/kernel.h>
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#include <linux/jiffies.h>
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#include <linux/string.h>
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#include <linux/mm.h>
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#include <linux/socket.h>
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#include <linux/sockios.h>
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#include <linux/in.h>
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#include <linux/errno.h>
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#include <linux/interrupt.h>
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#include <linux/netdevice.h>
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#include <linux/skbuff.h>
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#include <linux/rtnetlink.h>
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#include <linux/init.h>
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#include <linux/rbtree.h>
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#include <linux/slab.h>
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#include <net/sock.h>
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#include <net/gen_stats.h>
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/*
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This code is NOT intended to be used for statistics collection,
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its purpose is to provide a base for statistical multiplexing
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for controlled load service.
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If you need only statistics, run a user level daemon which
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periodically reads byte counters.
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Unfortunately, rate estimation is not a very easy task.
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F.e. I did not find a simple way to estimate the current peak rate
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and even failed to formulate the problem 8)8)
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So I preferred not to built an estimator into the scheduler,
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but run this task separately.
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Ideally, it should be kernel thread(s), but for now it runs
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from timers, which puts apparent top bounds on the number of rated
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flows, has minimal overhead on small, but is enough
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to handle controlled load service, sets of aggregates.
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We measure rate over A=(1<<interval) seconds and evaluate EWMA:
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avrate = avrate*(1-W) + rate*W
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where W is chosen as negative power of 2: W = 2^(-ewma_log)
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The resulting time constant is:
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T = A/(-ln(1-W))
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NOTES.
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* avbps is scaled by 2^5, avpps is scaled by 2^10.
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* both values are reported as 32 bit unsigned values. bps can
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overflow for fast links : max speed being 34360Mbit/sec
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* Minimal interval is HZ/4=250msec (it is the greatest common divisor
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for HZ=100 and HZ=1024 8)), maximal interval
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is (HZ*2^EST_MAX_INTERVAL)/4 = 8sec. Shorter intervals
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are too expensive, longer ones can be implemented
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at user level painlessly.
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*/
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#define EST_MAX_INTERVAL 5
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struct gen_estimator
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{
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struct list_head list;
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struct gnet_stats_basic_packed *bstats;
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struct gnet_stats_rate_est *rate_est;
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spinlock_t *stats_lock;
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int ewma_log;
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u64 last_bytes;
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u64 avbps;
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u32 last_packets;
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u32 avpps;
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struct rcu_head e_rcu;
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struct rb_node node;
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};
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struct gen_estimator_head
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{
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struct timer_list timer;
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struct list_head list;
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};
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static struct gen_estimator_head elist[EST_MAX_INTERVAL+1];
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/* Protects against NULL dereference */
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static DEFINE_RWLOCK(est_lock);
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/* Protects against soft lockup during large deletion */
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static struct rb_root est_root = RB_ROOT;
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static DEFINE_SPINLOCK(est_tree_lock);
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static void est_timer(unsigned long arg)
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{
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int idx = (int)arg;
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struct gen_estimator *e;
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rcu_read_lock();
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list_for_each_entry_rcu(e, &elist[idx].list, list) {
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u64 nbytes;
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u64 brate;
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u32 npackets;
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u32 rate;
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spin_lock(e->stats_lock);
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read_lock(&est_lock);
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if (e->bstats == NULL)
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goto skip;
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nbytes = e->bstats->bytes;
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npackets = e->bstats->packets;
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brate = (nbytes - e->last_bytes)<<(7 - idx);
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e->last_bytes = nbytes;
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e->avbps += (brate >> e->ewma_log) - (e->avbps >> e->ewma_log);
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e->rate_est->bps = (e->avbps+0xF)>>5;
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rate = (npackets - e->last_packets)<<(12 - idx);
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e->last_packets = npackets;
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e->avpps += (rate >> e->ewma_log) - (e->avpps >> e->ewma_log);
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e->rate_est->pps = (e->avpps+0x1FF)>>10;
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skip:
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read_unlock(&est_lock);
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spin_unlock(e->stats_lock);
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}
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if (!list_empty(&elist[idx].list))
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mod_timer(&elist[idx].timer, jiffies + ((HZ/4) << idx));
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rcu_read_unlock();
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}
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static void gen_add_node(struct gen_estimator *est)
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{
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struct rb_node **p = &est_root.rb_node, *parent = NULL;
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while (*p) {
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struct gen_estimator *e;
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parent = *p;
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e = rb_entry(parent, struct gen_estimator, node);
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if (est->bstats > e->bstats)
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p = &parent->rb_right;
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else
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p = &parent->rb_left;
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}
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rb_link_node(&est->node, parent, p);
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rb_insert_color(&est->node, &est_root);
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}
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static
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struct gen_estimator *gen_find_node(const struct gnet_stats_basic_packed *bstats,
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const struct gnet_stats_rate_est *rate_est)
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{
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struct rb_node *p = est_root.rb_node;
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while (p) {
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struct gen_estimator *e;
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e = rb_entry(p, struct gen_estimator, node);
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if (bstats > e->bstats)
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p = p->rb_right;
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else if (bstats < e->bstats || rate_est != e->rate_est)
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p = p->rb_left;
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else
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return e;
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}
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return NULL;
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}
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/**
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* gen_new_estimator - create a new rate estimator
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* @bstats: basic statistics
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* @rate_est: rate estimator statistics
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* @stats_lock: statistics lock
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* @opt: rate estimator configuration TLV
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*
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* Creates a new rate estimator with &bstats as source and &rate_est
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* as destination. A new timer with the interval specified in the
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* configuration TLV is created. Upon each interval, the latest statistics
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* will be read from &bstats and the estimated rate will be stored in
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* &rate_est with the statistics lock grabed during this period.
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*
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* Returns 0 on success or a negative error code.
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*
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*/
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int gen_new_estimator(struct gnet_stats_basic_packed *bstats,
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struct gnet_stats_rate_est *rate_est,
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spinlock_t *stats_lock,
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struct nlattr *opt)
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{
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struct gen_estimator *est;
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struct gnet_estimator *parm = nla_data(opt);
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int idx;
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if (nla_len(opt) < sizeof(*parm))
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return -EINVAL;
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if (parm->interval < -2 || parm->interval > 3)
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return -EINVAL;
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est = kzalloc(sizeof(*est), GFP_KERNEL);
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if (est == NULL)
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return -ENOBUFS;
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idx = parm->interval + 2;
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est->bstats = bstats;
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est->rate_est = rate_est;
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est->stats_lock = stats_lock;
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est->ewma_log = parm->ewma_log;
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est->last_bytes = bstats->bytes;
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est->avbps = rate_est->bps<<5;
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est->last_packets = bstats->packets;
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est->avpps = rate_est->pps<<10;
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spin_lock_bh(&est_tree_lock);
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if (!elist[idx].timer.function) {
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INIT_LIST_HEAD(&elist[idx].list);
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setup_timer(&elist[idx].timer, est_timer, idx);
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}
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if (list_empty(&elist[idx].list))
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mod_timer(&elist[idx].timer, jiffies + ((HZ/4) << idx));
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list_add_rcu(&est->list, &elist[idx].list);
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gen_add_node(est);
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spin_unlock_bh(&est_tree_lock);
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return 0;
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}
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EXPORT_SYMBOL(gen_new_estimator);
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/**
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* gen_kill_estimator - remove a rate estimator
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* @bstats: basic statistics
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* @rate_est: rate estimator statistics
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*
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* Removes the rate estimator specified by &bstats and &rate_est.
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*
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* Note : Caller should respect an RCU grace period before freeing stats_lock
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*/
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void gen_kill_estimator(struct gnet_stats_basic_packed *bstats,
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struct gnet_stats_rate_est *rate_est)
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{
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struct gen_estimator *e;
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spin_lock_bh(&est_tree_lock);
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while ((e = gen_find_node(bstats, rate_est))) {
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rb_erase(&e->node, &est_root);
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write_lock(&est_lock);
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e->bstats = NULL;
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write_unlock(&est_lock);
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list_del_rcu(&e->list);
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kfree_rcu(e, e_rcu);
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}
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spin_unlock_bh(&est_tree_lock);
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}
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EXPORT_SYMBOL(gen_kill_estimator);
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/**
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* gen_replace_estimator - replace rate estimator configuration
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* @bstats: basic statistics
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* @rate_est: rate estimator statistics
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* @stats_lock: statistics lock
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* @opt: rate estimator configuration TLV
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*
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* Replaces the configuration of a rate estimator by calling
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* gen_kill_estimator() and gen_new_estimator().
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*
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* Returns 0 on success or a negative error code.
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*/
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int gen_replace_estimator(struct gnet_stats_basic_packed *bstats,
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struct gnet_stats_rate_est *rate_est,
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spinlock_t *stats_lock, struct nlattr *opt)
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{
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gen_kill_estimator(bstats, rate_est);
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return gen_new_estimator(bstats, rate_est, stats_lock, opt);
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}
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EXPORT_SYMBOL(gen_replace_estimator);
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/**
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* gen_estimator_active - test if estimator is currently in use
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* @bstats: basic statistics
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* @rate_est: rate estimator statistics
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*
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* Returns true if estimator is active, and false if not.
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*/
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bool gen_estimator_active(const struct gnet_stats_basic_packed *bstats,
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const struct gnet_stats_rate_est *rate_est)
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{
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bool res;
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ASSERT_RTNL();
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spin_lock_bh(&est_tree_lock);
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res = gen_find_node(bstats, rate_est) != NULL;
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spin_unlock_bh(&est_tree_lock);
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return res;
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}
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EXPORT_SYMBOL(gen_estimator_active);
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