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Diffstat (limited to 'net/sched/sch_sfq.c')
| -rw-r--r-- | net/sched/sch_sfq.c | 497 |
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 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"); |
