| /* |
| * 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/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_SCTP || |
| iph->protocol == IPPROTO_DCCP || |
| 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_SCTP || |
| iph->nexthdr == IPPROTO_DCCP || |
| 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++; |
| sch->qstats.backlog -= len; |
| 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++; |
| sch->qstats.backlog -= len; |
| 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; |
| } |
| sch->qstats.backlog += skb->len; |
| __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; |
| } |
| sch->qstats.backlog += skb->len; |
| __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--; |
| sch->qstats.backlog -= skb->len; |
| |
| /* 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"); |