From 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 Mon Sep 17 00:00:00 2001
From: Linus Torvalds <torvalds@ppc970.osdl.org>
Date: Sat, 16 Apr 2005 15:20:36 -0700
Subject: Linux-2.6.12-rc2

Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.

Let it rip!
---
 net/core/gen_estimator.c | 250 +++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 250 insertions(+)
 create mode 100644 net/core/gen_estimator.c

(limited to 'net/core/gen_estimator.c')

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);
-- 
cgit v1.2.3-59-g8ed1b