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 000000000000..8734bb7280e3
--- /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");