patch-2.1.99 linux/net/sched/estimator.c

• Lines: 184
• Date: Wed Apr 29 22:46:59 1998
• Orig file: v2.1.98/linux/net/sched/estimator.c
• Orig date: Wed Dec 31 16:00:00 1969

diff -u --recursive --new-file v2.1.98/linux/net/sched/estimator.c linux/net/sched/estimator.c
@@ -0,0 +1,183 @@
+/*
+ * 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 <asm/bitops.h>
+#include <linux/types.h>
+#include <linux/kernel.h>
+#include <linux/sched.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 <linux/proc_fs.h>
+#include <net/sock.h>
+#include <net/pkt_sched.h>
+
+/*
+   This text is NOT intended to be used for statistics collection,
+   its purpose is to provide base for statistical multiplexing
+   for controlled load service.
+   If you need only statistics, run user level daemon, which will
+   periodically read byte counters.
+
+   Unfortunately, rate estimation is not very easy task.
+   F.e. I did not find a simple way to estimate current peak rate
+   and even failed to formulate the problem 8)8)
+
+   So that I preferred not to built estimator in 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 number of rated
+   flows, but has minimal overhead on small, but 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)
+
+   Resulting time constant is:
+
+   T = A/(-ln(1-W))
+
+
+   NOTES.
+
+   * 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 least integer divisor
+     both for HZ=100 and HZ=1024 8)), maximal interval
+     is (HZ/4)*2^EST_MAX_INTERVAL = 8sec. Shorter intervals
+     are too expensive, longer ones can be implemented
+     at user level painlessly.
+ */
+
+#if (HZ%4) != 0
+#error Bad HZ value.
+#endif
+
+#define EST_MAX_INTERVAL	5
+
+struct qdisc_estimator
+{
+	struct qdisc_estimator	*next;
+	struct tc_stats		*stats;
+	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];
+
+static void est_timer(unsigned long arg)
+{
+	int idx = (int)arg;
+	struct qdisc_estimator *e;
+
+	for (e = elist[idx].list; e; e = e->next) {
+		u64 nbytes = e->stats->bytes;
+		u32 npackets = e->stats->packets;
+		u32 rate;
+		
+		rate = (nbytes - e->last_bytes)<<(7 - idx);
+		e->last_bytes = nbytes;
+		e->avbps += ((long)rate - (long)e->avbps) >> e->ewma_log;
+		e->stats->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;
+	}
+
+	elist[idx].timer.expires = jiffies + ((HZ/4)<<idx);
+	add_timer(&elist[idx].timer);
+}
+
+int qdisc_new_estimator(struct tc_stats *stats, 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->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/4)<<est->interval);
+		elist[est->interval].timer.function = est_timer;
+		add_timer(&elist[est->interval].timer);
+	}
+	elist[est->interval].list = est;
+	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;
+			}
+			/* ATOMIC_SET */
+			*pest = est->next;
+			kfree(est);
+			killed++;
+		}
+		if (killed && elist[idx].list == NULL)
+			del_timer(&elist[idx].timer);
+	}
+}
+