| /* |
| * 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 <linux/types.h> |
| #include <linux/kernel.h> |
| #include <linux/jiffies.h> |
| #include <linux/string.h> |
| #include <linux/in.h> |
| #include <linux/errno.h> |
| #include <linux/init.h> |
| #include <linux/ipv6.h> |
| #include <linux/skbuff.h> |
| #include <linux/jhash.h> |
| #include <linux/slab.h> |
| #include <net/ip.h> |
| #include <net/netlink.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; |
| max mtu to 2^18-1; max 128 flows, number of hash buckets to 1024. |
| The only goal of this restrictions was that all data |
| fit into one 4K page on 32bit arches. |
| |
| It is easy to increase these values, but not in flight. */ |
| |
| #define SFQ_DEPTH 128 /* max number of packets per flow */ |
| #define SFQ_SLOTS 128 /* max number of flows */ |
| #define SFQ_EMPTY_SLOT 255 |
| #define SFQ_HASH_DIVISOR 1024 |
| /* We use 16 bits to store allot, and want to handle packets up to 64K |
| * Scale allot by 8 (1<<3) so that no overflow occurs. |
| */ |
| #define SFQ_ALLOT_SHIFT 3 |
| #define SFQ_ALLOT_SIZE(X) DIV_ROUND_UP(X, 1 << SFQ_ALLOT_SHIFT) |
| |
| /* This type should contain at least SFQ_DEPTH + SFQ_SLOTS values */ |
| typedef unsigned char sfq_index; |
| |
| /* |
| * We dont use pointers to save space. |
| * Small indexes [0 ... SFQ_SLOTS - 1] are 'pointers' to slots[] array |
| * while following values [SFQ_SLOTS ... SFQ_SLOTS + SFQ_DEPTH - 1] |
| * are 'pointers' to dep[] array |
| */ |
| struct sfq_head { |
| sfq_index next; |
| sfq_index prev; |
| }; |
| |
| struct sfq_slot { |
| struct sk_buff *skblist_next; |
| struct sk_buff *skblist_prev; |
| sfq_index qlen; /* number of skbs in skblist */ |
| sfq_index next; /* next slot in sfq chain */ |
| struct sfq_head dep; /* anchor in dep[] chains */ |
| unsigned short hash; /* hash value (index in ht[]) */ |
| short allot; /* credit for this slot */ |
| }; |
| |
| struct sfq_sched_data { |
| /* Parameters */ |
| int perturb_period; |
| unsigned int quantum; /* Allotment per round: MUST BE >= MTU */ |
| int limit; |
| |
| /* Variables */ |
| struct tcf_proto *filter_list; |
| struct timer_list perturb_timer; |
| u32 perturbation; |
| sfq_index cur_depth; /* depth of longest slot */ |
| unsigned short scaled_quantum; /* SFQ_ALLOT_SIZE(quantum) */ |
| struct sfq_slot *tail; /* current slot in round */ |
| sfq_index ht[SFQ_HASH_DIVISOR]; /* Hash table */ |
| struct sfq_slot slots[SFQ_SLOTS]; |
| struct sfq_head dep[SFQ_DEPTH]; /* Linked list of slots, indexed by depth */ |
| }; |
| |
| /* |
| * sfq_head are either in a sfq_slot or in dep[] array |
| */ |
| static inline struct sfq_head *sfq_dep_head(struct sfq_sched_data *q, sfq_index val) |
| { |
| if (val < SFQ_SLOTS) |
| return &q->slots[val].dep; |
| return &q->dep[val - SFQ_SLOTS]; |
| } |
| |
| static unsigned int sfq_fold_hash(struct sfq_sched_data *q, u32 h, u32 h1) |
| { |
| return jhash_2words(h, h1, q->perturbation) & (SFQ_HASH_DIVISOR - 1); |
| } |
| |
| static unsigned int sfq_hash(struct sfq_sched_data *q, struct sk_buff *skb) |
| { |
| u32 h, h2; |
| |
| switch (skb->protocol) { |
| case htons(ETH_P_IP): |
| { |
| const struct iphdr *iph; |
| int poff; |
| |
| if (!pskb_network_may_pull(skb, sizeof(*iph))) |
| goto err; |
| iph = ip_hdr(skb); |
| h = (__force u32)iph->daddr; |
| h2 = (__force u32)iph->saddr ^ iph->protocol; |
| if (iph->frag_off & htons(IP_MF | IP_OFFSET)) |
| break; |
| poff = proto_ports_offset(iph->protocol); |
| if (poff >= 0 && |
| pskb_network_may_pull(skb, iph->ihl * 4 + 4 + poff)) { |
| iph = ip_hdr(skb); |
| h2 ^= *(u32 *)((void *)iph + iph->ihl * 4 + poff); |
| } |
| break; |
| } |
| case htons(ETH_P_IPV6): |
| { |
| struct ipv6hdr *iph; |
| int poff; |
| |
| if (!pskb_network_may_pull(skb, sizeof(*iph))) |
| goto err; |
| iph = ipv6_hdr(skb); |
| h = (__force u32)iph->daddr.s6_addr32[3]; |
| h2 = (__force u32)iph->saddr.s6_addr32[3] ^ iph->nexthdr; |
| poff = proto_ports_offset(iph->nexthdr); |
| if (poff >= 0 && |
| pskb_network_may_pull(skb, sizeof(*iph) + 4 + poff)) { |
| iph = ipv6_hdr(skb); |
| h2 ^= *(u32 *)((void *)iph + sizeof(*iph) + poff); |
| } |
| break; |
| } |
| default: |
| err: |
| h = (unsigned long)skb_dst(skb) ^ (__force u32)skb->protocol; |
| h2 = (unsigned long)skb->sk; |
| } |
| |
| return sfq_fold_hash(q, h, h2); |
| } |
| |
| static unsigned int sfq_classify(struct sk_buff *skb, struct Qdisc *sch, |
| int *qerr) |
| { |
| struct sfq_sched_data *q = qdisc_priv(sch); |
| struct tcf_result res; |
| int result; |
| |
| if (TC_H_MAJ(skb->priority) == sch->handle && |
| TC_H_MIN(skb->priority) > 0 && |
| TC_H_MIN(skb->priority) <= SFQ_HASH_DIVISOR) |
| return TC_H_MIN(skb->priority); |
| |
| if (!q->filter_list) |
| return sfq_hash(q, skb) + 1; |
| |
| *qerr = NET_XMIT_SUCCESS | __NET_XMIT_BYPASS; |
| result = tc_classify(skb, q->filter_list, &res); |
| if (result >= 0) { |
| #ifdef CONFIG_NET_CLS_ACT |
| switch (result) { |
| case TC_ACT_STOLEN: |
| case TC_ACT_QUEUED: |
| *qerr = NET_XMIT_SUCCESS | __NET_XMIT_STOLEN; |
| case TC_ACT_SHOT: |
| return 0; |
| } |
| #endif |
| if (TC_H_MIN(res.classid) <= SFQ_HASH_DIVISOR) |
| return TC_H_MIN(res.classid); |
| } |
| return 0; |
| } |
| |
| /* |
| * x : slot number [0 .. SFQ_SLOTS - 1] |
| */ |
| static inline void sfq_link(struct sfq_sched_data *q, sfq_index x) |
| { |
| sfq_index p, n; |
| int qlen = q->slots[x].qlen; |
| |
| p = qlen + SFQ_SLOTS; |
| n = q->dep[qlen].next; |
| |
| q->slots[x].dep.next = n; |
| q->slots[x].dep.prev = p; |
| |
| q->dep[qlen].next = x; /* sfq_dep_head(q, p)->next = x */ |
| sfq_dep_head(q, n)->prev = x; |
| } |
| |
| #define sfq_unlink(q, x, n, p) \ |
| n = q->slots[x].dep.next; \ |
| p = q->slots[x].dep.prev; \ |
| sfq_dep_head(q, p)->next = n; \ |
| sfq_dep_head(q, n)->prev = p |
| |
| |
| static inline void sfq_dec(struct sfq_sched_data *q, sfq_index x) |
| { |
| sfq_index p, n; |
| int d; |
| |
| sfq_unlink(q, x, n, p); |
| |
| d = q->slots[x].qlen--; |
| if (n == p && q->cur_depth == d) |
| q->cur_depth--; |
| sfq_link(q, x); |
| } |
| |
| static inline void sfq_inc(struct sfq_sched_data *q, sfq_index x) |
| { |
| sfq_index p, n; |
| int d; |
| |
| sfq_unlink(q, x, n, p); |
| |
| d = ++q->slots[x].qlen; |
| if (q->cur_depth < d) |
| q->cur_depth = d; |
| sfq_link(q, x); |
| } |
| |
| /* helper functions : might be changed when/if skb use a standard list_head */ |
| |
| /* remove one skb from tail of slot queue */ |
| static inline struct sk_buff *slot_dequeue_tail(struct sfq_slot *slot) |
| { |
| struct sk_buff *skb = slot->skblist_prev; |
| |
| slot->skblist_prev = skb->prev; |
| skb->prev->next = (struct sk_buff *)slot; |
| skb->next = skb->prev = NULL; |
| return skb; |
| } |
| |
| /* remove one skb from head of slot queue */ |
| static inline struct sk_buff *slot_dequeue_head(struct sfq_slot *slot) |
| { |
| struct sk_buff *skb = slot->skblist_next; |
| |
| slot->skblist_next = skb->next; |
| skb->next->prev = (struct sk_buff *)slot; |
| skb->next = skb->prev = NULL; |
| return skb; |
| } |
| |
| static inline void slot_queue_init(struct sfq_slot *slot) |
| { |
| slot->skblist_prev = slot->skblist_next = (struct sk_buff *)slot; |
| } |
| |
| /* add skb to slot queue (tail add) */ |
| static inline void slot_queue_add(struct sfq_slot *slot, struct sk_buff *skb) |
| { |
| skb->prev = slot->skblist_prev; |
| skb->next = (struct sk_buff *)slot; |
| slot->skblist_prev->next = skb; |
| slot->skblist_prev = skb; |
| } |
| |
| #define slot_queue_walk(slot, skb) \ |
| for (skb = slot->skblist_next; \ |
| skb != (struct sk_buff *)slot; \ |
| skb = skb->next) |
| |
| static unsigned int sfq_drop(struct Qdisc *sch) |
| { |
| struct sfq_sched_data *q = qdisc_priv(sch); |
| sfq_index x, d = q->cur_depth; |
| struct sk_buff *skb; |
| unsigned int len; |
| struct sfq_slot *slot; |
| |
| /* Queue is full! Find the longest slot and drop tail packet from it */ |
| if (d > 1) { |
| x = q->dep[d].next; |
| slot = &q->slots[x]; |
| drop: |
| skb = slot_dequeue_tail(slot); |
| len = qdisc_pkt_len(skb); |
| sfq_dec(q, x); |
| kfree_skb(skb); |
| 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. */ |
| x = q->tail->next; |
| slot = &q->slots[x]; |
| q->tail->next = slot->next; |
| q->ht[slot->hash] = SFQ_EMPTY_SLOT; |
| goto drop; |
| } |
| |
| return 0; |
| } |
| |
| static int |
| sfq_enqueue(struct sk_buff *skb, struct Qdisc *sch) |
| { |
| struct sfq_sched_data *q = qdisc_priv(sch); |
| unsigned int hash; |
| sfq_index x; |
| struct sfq_slot *slot; |
| int uninitialized_var(ret); |
| |
| hash = sfq_classify(skb, sch, &ret); |
| if (hash == 0) { |
| if (ret & __NET_XMIT_BYPASS) |
| sch->qstats.drops++; |
| kfree_skb(skb); |
| return ret; |
| } |
| hash--; |
| |
| x = q->ht[hash]; |
| slot = &q->slots[x]; |
| if (x == SFQ_EMPTY_SLOT) { |
| x = q->dep[0].next; /* get a free slot */ |
| q->ht[hash] = x; |
| slot = &q->slots[x]; |
| slot->hash = hash; |
| } |
| |
| /* If selected queue has length q->limit, do simple tail drop, |
| * i.e. drop _this_ packet. |
| */ |
| if (slot->qlen >= q->limit) |
| return qdisc_drop(skb, sch); |
| |
| sch->qstats.backlog += qdisc_pkt_len(skb); |
| slot_queue_add(slot, skb); |
| sfq_inc(q, x); |
| if (slot->qlen == 1) { /* The flow is new */ |
| if (q->tail == NULL) { /* It is the first flow */ |
| slot->next = x; |
| } else { |
| slot->next = q->tail->next; |
| q->tail->next = x; |
| } |
| q->tail = slot; |
| slot->allot = q->scaled_quantum; |
| } |
| if (++sch->q.qlen <= q->limit) { |
| qdisc_bstats_update(sch, skb); |
| return NET_XMIT_SUCCESS; |
| } |
| |
| sfq_drop(sch); |
| return NET_XMIT_CN; |
| } |
| |
| static struct sk_buff * |
| sfq_peek(struct Qdisc *sch) |
| { |
| struct sfq_sched_data *q = qdisc_priv(sch); |
| |
| /* No active slots */ |
| if (q->tail == NULL) |
| return NULL; |
| |
| return q->slots[q->tail->next].skblist_next; |
| } |
| |
| static struct sk_buff * |
| sfq_dequeue(struct Qdisc *sch) |
| { |
| struct sfq_sched_data *q = qdisc_priv(sch); |
| struct sk_buff *skb; |
| sfq_index a, next_a; |
| struct sfq_slot *slot; |
| |
| /* No active slots */ |
| if (q->tail == NULL) |
| return NULL; |
| |
| next_slot: |
| a = q->tail->next; |
| slot = &q->slots[a]; |
| if (slot->allot <= 0) { |
| q->tail = slot; |
| slot->allot += q->scaled_quantum; |
| goto next_slot; |
| } |
| skb = slot_dequeue_head(slot); |
| sfq_dec(q, a); |
| sch->q.qlen--; |
| sch->qstats.backlog -= qdisc_pkt_len(skb); |
| |
| /* Is the slot empty? */ |
| if (slot->qlen == 0) { |
| q->ht[slot->hash] = SFQ_EMPTY_SLOT; |
| next_a = slot->next; |
| if (a == next_a) { |
| q->tail = NULL; /* no more active slots */ |
| return skb; |
| } |
| q->tail->next = next_a; |
| } else { |
| slot->allot -= SFQ_ALLOT_SIZE(qdisc_pkt_len(skb)); |
| } |
| 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(); |
| |
| if (q->perturb_period) |
| mod_timer(&q->perturb_timer, jiffies + q->perturb_period); |
| } |
| |
| static int sfq_change(struct Qdisc *sch, struct nlattr *opt) |
| { |
| struct sfq_sched_data *q = qdisc_priv(sch); |
| struct tc_sfq_qopt *ctl = nla_data(opt); |
| unsigned int qlen; |
| |
| if (opt->nla_len < nla_attr_size(sizeof(*ctl))) |
| return -EINVAL; |
| |
| sch_tree_lock(sch); |
| q->quantum = ctl->quantum ? : psched_mtu(qdisc_dev(sch)); |
| q->scaled_quantum = SFQ_ALLOT_SIZE(q->quantum); |
| q->perturb_period = ctl->perturb_period * HZ; |
| if (ctl->limit) |
| q->limit = min_t(u32, ctl->limit, SFQ_DEPTH - 1); |
| |
| qlen = sch->q.qlen; |
| while (sch->q.qlen > q->limit) |
| sfq_drop(sch); |
| qdisc_tree_decrease_qlen(sch, qlen - sch->q.qlen); |
| |
| del_timer(&q->perturb_timer); |
| if (q->perturb_period) { |
| mod_timer(&q->perturb_timer, jiffies + q->perturb_period); |
| q->perturbation = net_random(); |
| } |
| sch_tree_unlock(sch); |
| return 0; |
| } |
| |
| static int sfq_init(struct Qdisc *sch, struct nlattr *opt) |
| { |
| struct sfq_sched_data *q = qdisc_priv(sch); |
| int i; |
| |
| q->perturb_timer.function = sfq_perturbation; |
| q->perturb_timer.data = (unsigned long)sch; |
| init_timer_deferrable(&q->perturb_timer); |
| |
| for (i = 0; i < SFQ_HASH_DIVISOR; i++) |
| q->ht[i] = SFQ_EMPTY_SLOT; |
| |
| for (i = 0; i < SFQ_DEPTH; i++) { |
| q->dep[i].next = i + SFQ_SLOTS; |
| q->dep[i].prev = i + SFQ_SLOTS; |
| } |
| |
| q->limit = SFQ_DEPTH - 1; |
| q->cur_depth = 0; |
| q->tail = NULL; |
| if (opt == NULL) { |
| q->quantum = psched_mtu(qdisc_dev(sch)); |
| q->scaled_quantum = SFQ_ALLOT_SIZE(q->quantum); |
| q->perturb_period = 0; |
| q->perturbation = net_random(); |
| } else { |
| int err = sfq_change(sch, opt); |
| if (err) |
| return err; |
| } |
| |
| for (i = 0; i < SFQ_SLOTS; i++) { |
| slot_queue_init(&q->slots[i]); |
| sfq_link(q, i); |
| } |
| return 0; |
| } |
| |
| static void sfq_destroy(struct Qdisc *sch) |
| { |
| struct sfq_sched_data *q = qdisc_priv(sch); |
| |
| tcf_destroy_chain(&q->filter_list); |
| q->perturb_period = 0; |
| del_timer_sync(&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_pointer(skb); |
| 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; |
| |
| NLA_PUT(skb, TCA_OPTIONS, sizeof(opt), &opt); |
| |
| return skb->len; |
| |
| nla_put_failure: |
| nlmsg_trim(skb, b); |
| return -1; |
| } |
| |
| static struct Qdisc *sfq_leaf(struct Qdisc *sch, unsigned long arg) |
| { |
| return NULL; |
| } |
| |
| static unsigned long sfq_get(struct Qdisc *sch, u32 classid) |
| { |
| return 0; |
| } |
| |
| static unsigned long sfq_bind(struct Qdisc *sch, unsigned long parent, |
| u32 classid) |
| { |
| return 0; |
| } |
| |
| static void sfq_put(struct Qdisc *q, unsigned long cl) |
| { |
| } |
| |
| static struct tcf_proto **sfq_find_tcf(struct Qdisc *sch, unsigned long cl) |
| { |
| struct sfq_sched_data *q = qdisc_priv(sch); |
| |
| if (cl) |
| return NULL; |
| return &q->filter_list; |
| } |
| |
| static int sfq_dump_class(struct Qdisc *sch, unsigned long cl, |
| struct sk_buff *skb, struct tcmsg *tcm) |
| { |
| tcm->tcm_handle |= TC_H_MIN(cl); |
| return 0; |
| } |
| |
| static int sfq_dump_class_stats(struct Qdisc *sch, unsigned long cl, |
| struct gnet_dump *d) |
| { |
| struct sfq_sched_data *q = qdisc_priv(sch); |
| sfq_index idx = q->ht[cl - 1]; |
| struct gnet_stats_queue qs = { 0 }; |
| struct tc_sfq_xstats xstats = { 0 }; |
| struct sk_buff *skb; |
| |
| if (idx != SFQ_EMPTY_SLOT) { |
| const struct sfq_slot *slot = &q->slots[idx]; |
| |
| xstats.allot = slot->allot << SFQ_ALLOT_SHIFT; |
| qs.qlen = slot->qlen; |
| slot_queue_walk(slot, skb) |
| qs.backlog += qdisc_pkt_len(skb); |
| } |
| if (gnet_stats_copy_queue(d, &qs) < 0) |
| return -1; |
| return gnet_stats_copy_app(d, &xstats, sizeof(xstats)); |
| } |
| |
| static void sfq_walk(struct Qdisc *sch, struct qdisc_walker *arg) |
| { |
| struct sfq_sched_data *q = qdisc_priv(sch); |
| unsigned int i; |
| |
| if (arg->stop) |
| return; |
| |
| for (i = 0; i < SFQ_HASH_DIVISOR; i++) { |
| if (q->ht[i] == SFQ_EMPTY_SLOT || |
| arg->count < arg->skip) { |
| arg->count++; |
| continue; |
| } |
| if (arg->fn(sch, i + 1, arg) < 0) { |
| arg->stop = 1; |
| break; |
| } |
| arg->count++; |
| } |
| } |
| |
| static const struct Qdisc_class_ops sfq_class_ops = { |
| .leaf = sfq_leaf, |
| .get = sfq_get, |
| .put = sfq_put, |
| .tcf_chain = sfq_find_tcf, |
| .bind_tcf = sfq_bind, |
| .unbind_tcf = sfq_put, |
| .dump = sfq_dump_class, |
| .dump_stats = sfq_dump_class_stats, |
| .walk = sfq_walk, |
| }; |
| |
| static struct Qdisc_ops sfq_qdisc_ops __read_mostly = { |
| .cl_ops = &sfq_class_ops, |
| .id = "sfq", |
| .priv_size = sizeof(struct sfq_sched_data), |
| .enqueue = sfq_enqueue, |
| .dequeue = sfq_dequeue, |
| .peek = sfq_peek, |
| .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"); |