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!

1 files changed, 497 insertions, 0 deletions

diff --git a/net/sched/sch_sfq.c b/net/sched/sch_sfq.c
new file mode 100644
index 00000000000..8734bb7280e
--- /dev/null
+++ b/net/sched/sch_sfq.c
@@ -0,0 +1,497 @@
+/*
+ * net/sched/sch_sfq.c	Stochastic Fairness Queueing discipline.
+ *
+ *		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 <linux/config.h>
+#include <linux/module.h>
+#include <asm/uaccess.h>
+#include <asm/system.h>
+#include <linux/bitops.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/if_ether.h>
+#include <linux/inet.h>
+#include <linux/netdevice.h>
+#include <linux/etherdevice.h>
+#include <linux/notifier.h>
+#include <linux/init.h>
+#include <net/ip.h>
+#include <linux/ipv6.h>
+#include <net/route.h>
+#include <linux/skbuff.h>
+#include <net/sock.h>
+#include <net/pkt_sched.h>
+
+
+/*	Stochastic Fairness Queuing algorithm.
+	=======================================
+
+	Source:
+	Paul E. McKenney "Stochastic Fairness Queuing",
+	IEEE INFOCOMM'90 Proceedings, San Francisco, 1990.
+
+	Paul E. McKenney "Stochastic Fairness Queuing",
+	"Interworking: Research and Experience", v.2, 1991, p.113-131.
+
+
+	See also:
+	M. Shreedhar and George Varghese "Efficient Fair
+	Queuing using Deficit Round Robin", Proc. SIGCOMM 95.
+
+
+	This is not the thing that is usually called (W)FQ nowadays. 
+	It does not use any timestamp mechanism, but instead
+	processes queues in round-robin order.
+
+	ADVANTAGE:
+
+	- It is very cheap. Both CPU and memory requirements are minimal.
+
+	DRAWBACKS:
+
+	- "Stochastic" -> It is not 100% fair. 
+	When hash collisions occur, several flows are considered as one.
+
+	- "Round-robin" -> It introduces larger delays than virtual clock
+	based schemes, and should not be used for isolating interactive
+	traffic	from non-interactive. It means, that this scheduler
+	should be used as leaf of CBQ or P3, which put interactive traffic
+	to higher priority band.
+
+	We still need true WFQ for top level CSZ, but using WFQ
+	for the best effort traffic is absolutely pointless:
+	SFQ is superior for this purpose.
+
+	IMPLEMENTATION:
+	This implementation limits maximal queue length to 128;
+	maximal mtu to 2^15-1; number of hash buckets to 1024.
+	The only goal of this restrictions was that all data
+	fit into one 4K page :-). Struct sfq_sched_data is
+	organized in anti-cache manner: all the data for a bucket
+	are scattered over different locations. This is not good,
+	but it allowed me to put it into 4K.
+
+	It is easy to increase these values, but not in flight.  */
+
+#define SFQ_DEPTH		128
+#define SFQ_HASH_DIVISOR	1024
+
+/* This type should contain at least SFQ_DEPTH*2 values */
+typedef unsigned char sfq_index;
+
+struct sfq_head
+{
+	sfq_index	next;
+	sfq_index	prev;
+};
+
+struct sfq_sched_data
+{
+/* Parameters */
+	int		perturb_period;
+	unsigned	quantum;	/* Allotment per round: MUST BE >= MTU */
+	int		limit;
+
+/* Variables */
+	struct timer_list perturb_timer;
+	int		perturbation;
+	sfq_index	tail;		/* Index of current slot in round */
+	sfq_index	max_depth;	/* Maximal depth */
+
+	sfq_index	ht[SFQ_HASH_DIVISOR];	/* Hash table */
+	sfq_index	next[SFQ_DEPTH];	/* Active slots link */
+	short		allot[SFQ_DEPTH];	/* Current allotment per slot */
+	unsigned short	hash[SFQ_DEPTH];	/* Hash value indexed by slots */
+	struct sk_buff_head	qs[SFQ_DEPTH];		/* Slot queue */
+	struct sfq_head	dep[SFQ_DEPTH*2];	/* Linked list of slots, indexed by depth */
+};
+
+static __inline__ unsigned sfq_fold_hash(struct sfq_sched_data *q, u32 h, u32 h1)
+{
+	int pert = q->perturbation;
+
+	/* Have we any rotation primitives? If not, WHY? */
+	h ^= (h1<<pert) ^ (h1>>(0x1F - pert));
+	h ^= h>>10;
+	return h & 0x3FF;
+}
+
+static unsigned sfq_hash(struct sfq_sched_data *q, struct sk_buff *skb)
+{
+	u32 h, h2;
+
+	switch (skb->protocol) {
+	case __constant_htons(ETH_P_IP):
+	{
+		struct iphdr *iph = skb->nh.iph;
+		h = iph->daddr;
+		h2 = iph->saddr^iph->protocol;
+		if (!(iph->frag_off&htons(IP_MF|IP_OFFSET)) &&
+		    (iph->protocol == IPPROTO_TCP ||
+		     iph->protocol == IPPROTO_UDP ||
+		     iph->protocol == IPPROTO_ESP))
+			h2 ^= *(((u32*)iph) + iph->ihl);
+		break;
+	}
+	case __constant_htons(ETH_P_IPV6):
+	{
+		struct ipv6hdr *iph = skb->nh.ipv6h;
+		h = iph->daddr.s6_addr32[3];
+		h2 = iph->saddr.s6_addr32[3]^iph->nexthdr;
+		if (iph->nexthdr == IPPROTO_TCP ||
+		    iph->nexthdr == IPPROTO_UDP ||
+		    iph->nexthdr == IPPROTO_ESP)
+			h2 ^= *(u32*)&iph[1];
+		break;
+	}
+	default:
+		h = (u32)(unsigned long)skb->dst^skb->protocol;
+		h2 = (u32)(unsigned long)skb->sk;
+	}
+	return sfq_fold_hash(q, h, h2);
+}
+
+static inline void sfq_link(struct sfq_sched_data *q, sfq_index x)
+{
+	sfq_index p, n;
+	int d = q->qs[x].qlen + SFQ_DEPTH;
+
+	p = d;
+	n = q->dep[d].next;
+	q->dep[x].next = n;
+	q->dep[x].prev = p;
+	q->dep[p].next = q->dep[n].prev = x;
+}
+
+static inline void sfq_dec(struct sfq_sched_data *q, sfq_index x)
+{
+	sfq_index p, n;
+
+	n = q->dep[x].next;
+	p = q->dep[x].prev;
+	q->dep[p].next = n;
+	q->dep[n].prev = p;
+
+	if (n == p && q->max_depth == q->qs[x].qlen + 1)
+		q->max_depth--;
+
+	sfq_link(q, x);
+}
+
+static inline void sfq_inc(struct sfq_sched_data *q, sfq_index x)
+{
+	sfq_index p, n;
+	int d;
+
+	n = q->dep[x].next;
+	p = q->dep[x].prev;
+	q->dep[p].next = n;
+	q->dep[n].prev = p;
+	d = q->qs[x].qlen;
+	if (q->max_depth < d)
+		q->max_depth = d;
+
+	sfq_link(q, x);
+}
+
+static unsigned int sfq_drop(struct Qdisc *sch)
+{
+	struct sfq_sched_data *q = qdisc_priv(sch);
+	sfq_index d = q->max_depth;
+	struct sk_buff *skb;
+	unsigned int len;
+
+	/* Queue is full! Find the longest slot and
+	   drop a packet from it */
+
+	if (d > 1) {
+		sfq_index x = q->dep[d+SFQ_DEPTH].next;
+		skb = q->qs[x].prev;
+		len = skb->len;
+		__skb_unlink(skb, &q->qs[x]);
+		kfree_skb(skb);
+		sfq_dec(q, x);
+		sch->q.qlen--;
+		sch->qstats.drops++;
+		return len;
+	}
+
+	if (d == 1) {
+		/* It is difficult to believe, but ALL THE SLOTS HAVE LENGTH 1. */
+		d = q->next[q->tail];
+		q->next[q->tail] = q->next[d];
+		q->allot[q->next[d]] += q->quantum;
+		skb = q->qs[d].prev;
+		len = skb->len;
+		__skb_unlink(skb, &q->qs[d]);
+		kfree_skb(skb);
+		sfq_dec(q, d);
+		sch->q.qlen--;
+		q->ht[q->hash[d]] = SFQ_DEPTH;
+		sch->qstats.drops++;
+		return len;
+	}
+
+	return 0;
+}
+
+static int
+sfq_enqueue(struct sk_buff *skb, struct Qdisc* sch)
+{
+	struct sfq_sched_data *q = qdisc_priv(sch);
+	unsigned hash = sfq_hash(q, skb);
+	sfq_index x;
+
+	x = q->ht[hash];
+	if (x == SFQ_DEPTH) {
+		q->ht[hash] = x = q->dep[SFQ_DEPTH].next;
+		q->hash[x] = hash;
+	}
+	__skb_queue_tail(&q->qs[x], skb);
+	sfq_inc(q, x);
+	if (q->qs[x].qlen == 1) {		/* The flow is new */
+		if (q->tail == SFQ_DEPTH) {	/* It is the first flow */
+			q->tail = x;
+			q->next[x] = x;
+			q->allot[x] = q->quantum;
+		} else {
+			q->next[x] = q->next[q->tail];
+			q->next[q->tail] = x;
+			q->tail = x;
+		}
+	}
+	if (++sch->q.qlen < q->limit-1) {
+		sch->bstats.bytes += skb->len;
+		sch->bstats.packets++;
+		return 0;
+	}
+
+	sfq_drop(sch);
+	return NET_XMIT_CN;
+}
+
+static int
+sfq_requeue(struct sk_buff *skb, struct Qdisc* sch)
+{
+	struct sfq_sched_data *q = qdisc_priv(sch);
+	unsigned hash = sfq_hash(q, skb);
+	sfq_index x;
+
+	x = q->ht[hash];
+	if (x == SFQ_DEPTH) {
+		q->ht[hash] = x = q->dep[SFQ_DEPTH].next;
+		q->hash[x] = hash;
+	}
+	__skb_queue_head(&q->qs[x], skb);
+	sfq_inc(q, x);
+	if (q->qs[x].qlen == 1) {		/* The flow is new */
+		if (q->tail == SFQ_DEPTH) {	/* It is the first flow */
+			q->tail = x;
+			q->next[x] = x;
+			q->allot[x] = q->quantum;
+		} else {
+			q->next[x] = q->next[q->tail];
+			q->next[q->tail] = x;
+			q->tail = x;
+		}
+	}
+	if (++sch->q.qlen < q->limit - 1) {
+		sch->qstats.requeues++;
+		return 0;
+	}
+
+	sch->qstats.drops++;
+	sfq_drop(sch);
+	return NET_XMIT_CN;
+}
+
+
+
+
+static struct sk_buff *
+sfq_dequeue(struct Qdisc* sch)
+{
+	struct sfq_sched_data *q = qdisc_priv(sch);
+	struct sk_buff *skb;
+	sfq_index a, old_a;
+
+	/* No active slots */
+	if (q->tail == SFQ_DEPTH)
+		return NULL;
+
+	a = old_a = q->next[q->tail];
+
+	/* Grab packet */
+	skb = __skb_dequeue(&q->qs[a]);
+	sfq_dec(q, a);
+	sch->q.qlen--;
+
+	/* Is the slot empty? */
+	if (q->qs[a].qlen == 0) {
+		q->ht[q->hash[a]] = SFQ_DEPTH;
+		a = q->next[a];
+		if (a == old_a) {
+			q->tail = SFQ_DEPTH;
+			return skb;
+		}
+		q->next[q->tail] = a;
+		q->allot[a] += q->quantum;
+	} else if ((q->allot[a] -= skb->len) <= 0) {
+		q->tail = a;
+		a = q->next[a];
+		q->allot[a] += q->quantum;
+	}
+	return skb;
+}
+
+static void
+sfq_reset(struct Qdisc* sch)
+{
+	struct sk_buff *skb;
+
+	while ((skb = sfq_dequeue(sch)) != NULL)
+		kfree_skb(skb);
+}
+
+static void sfq_perturbation(unsigned long arg)
+{
+	struct Qdisc *sch = (struct Qdisc*)arg;
+	struct sfq_sched_data *q = qdisc_priv(sch);
+
+	q->perturbation = net_random()&0x1F;
+
+	if (q->perturb_period) {
+		q->perturb_timer.expires = jiffies + q->perturb_period;
+		add_timer(&q->perturb_timer);
+	}
+}
+
+static int sfq_change(struct Qdisc *sch, struct rtattr *opt)
+{
+	struct sfq_sched_data *q = qdisc_priv(sch);
+	struct tc_sfq_qopt *ctl = RTA_DATA(opt);
+
+	if (opt->rta_len < RTA_LENGTH(sizeof(*ctl)))
+		return -EINVAL;
+
+	sch_tree_lock(sch);
+	q->quantum = ctl->quantum ? : psched_mtu(sch->dev);
+	q->perturb_period = ctl->perturb_period*HZ;
+	if (ctl->limit)
+		q->limit = min_t(u32, ctl->limit, SFQ_DEPTH);
+
+	while (sch->q.qlen >= q->limit-1)
+		sfq_drop(sch);
+
+	del_timer(&q->perturb_timer);
+	if (q->perturb_period) {
+		q->perturb_timer.expires = jiffies + q->perturb_period;
+		add_timer(&q->perturb_timer);
+	}
+	sch_tree_unlock(sch);
+	return 0;
+}
+
+static int sfq_init(struct Qdisc *sch, struct rtattr *opt)
+{
+	struct sfq_sched_data *q = qdisc_priv(sch);
+	int i;
+
+	init_timer(&q->perturb_timer);
+	q->perturb_timer.data = (unsigned long)sch;
+	q->perturb_timer.function = sfq_perturbation;
+
+	for (i=0; i<SFQ_HASH_DIVISOR; i++)
+		q->ht[i] = SFQ_DEPTH;
+	for (i=0; i<SFQ_DEPTH; i++) {
+		skb_queue_head_init(&q->qs[i]);
+		q->dep[i+SFQ_DEPTH].next = i+SFQ_DEPTH;
+		q->dep[i+SFQ_DEPTH].prev = i+SFQ_DEPTH;
+	}
+	q->limit = SFQ_DEPTH;
+	q->max_depth = 0;
+	q->tail = SFQ_DEPTH;
+	if (opt == NULL) {
+		q->quantum = psched_mtu(sch->dev);
+		q->perturb_period = 0;
+	} else {
+		int err = sfq_change(sch, opt);
+		if (err)
+			return err;
+	}
+	for (i=0; i<SFQ_DEPTH; i++)
+		sfq_link(q, i);
+	return 0;
+}
+
+static void sfq_destroy(struct Qdisc *sch)
+{
+	struct sfq_sched_data *q = qdisc_priv(sch);
+	del_timer(&q->perturb_timer);
+}
+
+static int sfq_dump(struct Qdisc *sch, struct sk_buff *skb)
+{
+	struct sfq_sched_data *q = qdisc_priv(sch);
+	unsigned char	 *b = skb->tail;
+	struct tc_sfq_qopt opt;
+
+	opt.quantum = q->quantum;
+	opt.perturb_period = q->perturb_period/HZ;
+
+	opt.limit = q->limit;
+	opt.divisor = SFQ_HASH_DIVISOR;
+	opt.flows = q->limit;
+
+	RTA_PUT(skb, TCA_OPTIONS, sizeof(opt), &opt);
+
+	return skb->len;
+
+rtattr_failure:
+	skb_trim(skb, b - skb->data);
+	return -1;
+}
+
+static struct Qdisc_ops sfq_qdisc_ops = {
+	.next		=	NULL,
+	.cl_ops		=	NULL,
+	.id		=	"sfq",
+	.priv_size	=	sizeof(struct sfq_sched_data),
+	.enqueue	=	sfq_enqueue,
+	.dequeue	=	sfq_dequeue,
+	.requeue	=	sfq_requeue,
+	.drop		=	sfq_drop,
+	.init		=	sfq_init,
+	.reset		=	sfq_reset,
+	.destroy	=	sfq_destroy,
+	.change		=	NULL,
+	.dump		=	sfq_dump,
+	.owner		=	THIS_MODULE,
+};
+
+static int __init sfq_module_init(void)
+{
+	return register_qdisc(&sfq_qdisc_ops);
+}
+static void __exit sfq_module_exit(void) 
+{
+	unregister_qdisc(&sfq_qdisc_ops);
+}
+module_init(sfq_module_init)
+module_exit(sfq_module_exit)
+MODULE_LICENSE("GPL");