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!
diff --git a/net/sched/sch_sfq.c b/net/sched/sch_sfq.c
new file mode 100644
index 0000000..8734bb7
--- /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");