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!
This commit is contained in:
Linus Torvalds
497
net/sched/sch_sfq.c
Normal file
497
net/sched/sch_sfq.c
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@@ -0,0 +1,497 @@
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/*
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* net/sched/sch_sfq.c Stochastic Fairness Queueing discipline.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version
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* 2 of the License, or (at your option) any later version.
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*
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* Authors: Alexey Kuznetsov, <kuznet@ms2.inr.ac.ru>
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*/
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#include <linux/config.h>
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#include <linux/module.h>
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#include <asm/uaccess.h>
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#include <asm/system.h>
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#include <linux/bitops.h>
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#include <linux/types.h>
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#include <linux/kernel.h>
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#include <linux/jiffies.h>
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#include <linux/string.h>
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#include <linux/mm.h>
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#include <linux/socket.h>
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#include <linux/sockios.h>
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#include <linux/in.h>
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#include <linux/errno.h>
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#include <linux/interrupt.h>
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#include <linux/if_ether.h>
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#include <linux/inet.h>
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#include <linux/netdevice.h>
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#include <linux/etherdevice.h>
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#include <linux/notifier.h>
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#include <linux/init.h>
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#include <net/ip.h>
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#include <linux/ipv6.h>
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#include <net/route.h>
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#include <linux/skbuff.h>
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#include <net/sock.h>
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#include <net/pkt_sched.h>
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/* Stochastic Fairness Queuing algorithm.
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=======================================
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Source:
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Paul E. McKenney "Stochastic Fairness Queuing",
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IEEE INFOCOMM'90 Proceedings, San Francisco, 1990.
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Paul E. McKenney "Stochastic Fairness Queuing",
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"Interworking: Research and Experience", v.2, 1991, p.113-131.
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See also:
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M. Shreedhar and George Varghese "Efficient Fair
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Queuing using Deficit Round Robin", Proc. SIGCOMM 95.
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This is not the thing that is usually called (W)FQ nowadays.
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It does not use any timestamp mechanism, but instead
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processes queues in round-robin order.
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ADVANTAGE:
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- It is very cheap. Both CPU and memory requirements are minimal.
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DRAWBACKS:
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- "Stochastic" -> It is not 100% fair.
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When hash collisions occur, several flows are considered as one.
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- "Round-robin" -> It introduces larger delays than virtual clock
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based schemes, and should not be used for isolating interactive
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traffic from non-interactive. It means, that this scheduler
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should be used as leaf of CBQ or P3, which put interactive traffic
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to higher priority band.
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We still need true WFQ for top level CSZ, but using WFQ
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for the best effort traffic is absolutely pointless:
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SFQ is superior for this purpose.
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IMPLEMENTATION:
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This implementation limits maximal queue length to 128;
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maximal mtu to 2^15-1; number of hash buckets to 1024.
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The only goal of this restrictions was that all data
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fit into one 4K page :-). Struct sfq_sched_data is
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organized in anti-cache manner: all the data for a bucket
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are scattered over different locations. This is not good,
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but it allowed me to put it into 4K.
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It is easy to increase these values, but not in flight. */
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#define SFQ_DEPTH 128
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#define SFQ_HASH_DIVISOR 1024
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/* This type should contain at least SFQ_DEPTH*2 values */
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typedef unsigned char sfq_index;
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struct sfq_head
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{
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sfq_index next;
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sfq_index prev;
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};
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struct sfq_sched_data
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{
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/* Parameters */
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int perturb_period;
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unsigned quantum; /* Allotment per round: MUST BE >= MTU */
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int limit;
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/* Variables */
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struct timer_list perturb_timer;
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int perturbation;
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sfq_index tail; /* Index of current slot in round */
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sfq_index max_depth; /* Maximal depth */
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sfq_index ht[SFQ_HASH_DIVISOR]; /* Hash table */
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sfq_index next[SFQ_DEPTH]; /* Active slots link */
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short allot[SFQ_DEPTH]; /* Current allotment per slot */
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unsigned short hash[SFQ_DEPTH]; /* Hash value indexed by slots */
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struct sk_buff_head qs[SFQ_DEPTH]; /* Slot queue */
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struct sfq_head dep[SFQ_DEPTH*2]; /* Linked list of slots, indexed by depth */
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};
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static __inline__ unsigned sfq_fold_hash(struct sfq_sched_data *q, u32 h, u32 h1)
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{
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int pert = q->perturbation;
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/* Have we any rotation primitives? If not, WHY? */
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h ^= (h1<<pert) ^ (h1>>(0x1F - pert));
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h ^= h>>10;
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return h & 0x3FF;
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}
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static unsigned sfq_hash(struct sfq_sched_data *q, struct sk_buff *skb)
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{
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u32 h, h2;
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switch (skb->protocol) {
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case __constant_htons(ETH_P_IP):
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{
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struct iphdr *iph = skb->nh.iph;
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h = iph->daddr;
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h2 = iph->saddr^iph->protocol;
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if (!(iph->frag_off&htons(IP_MF|IP_OFFSET)) &&
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(iph->protocol == IPPROTO_TCP ||
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iph->protocol == IPPROTO_UDP ||
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iph->protocol == IPPROTO_ESP))
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h2 ^= *(((u32*)iph) + iph->ihl);
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break;
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}
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case __constant_htons(ETH_P_IPV6):
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{
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struct ipv6hdr *iph = skb->nh.ipv6h;
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h = iph->daddr.s6_addr32[3];
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h2 = iph->saddr.s6_addr32[3]^iph->nexthdr;
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if (iph->nexthdr == IPPROTO_TCP ||
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iph->nexthdr == IPPROTO_UDP ||
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iph->nexthdr == IPPROTO_ESP)
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h2 ^= *(u32*)&iph[1];
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break;
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}
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default:
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h = (u32)(unsigned long)skb->dst^skb->protocol;
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h2 = (u32)(unsigned long)skb->sk;
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}
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return sfq_fold_hash(q, h, h2);
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}
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static inline void sfq_link(struct sfq_sched_data *q, sfq_index x)
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{
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sfq_index p, n;
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int d = q->qs[x].qlen + SFQ_DEPTH;
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p = d;
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n = q->dep[d].next;
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q->dep[x].next = n;
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q->dep[x].prev = p;
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q->dep[p].next = q->dep[n].prev = x;
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}
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static inline void sfq_dec(struct sfq_sched_data *q, sfq_index x)
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{
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sfq_index p, n;
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n = q->dep[x].next;
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p = q->dep[x].prev;
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q->dep[p].next = n;
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q->dep[n].prev = p;
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if (n == p && q->max_depth == q->qs[x].qlen + 1)
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q->max_depth--;
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sfq_link(q, x);
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}
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static inline void sfq_inc(struct sfq_sched_data *q, sfq_index x)
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{
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sfq_index p, n;
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int d;
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n = q->dep[x].next;
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p = q->dep[x].prev;
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q->dep[p].next = n;
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q->dep[n].prev = p;
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d = q->qs[x].qlen;
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if (q->max_depth < d)
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q->max_depth = d;
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sfq_link(q, x);
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}
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static unsigned int sfq_drop(struct Qdisc *sch)
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{
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struct sfq_sched_data *q = qdisc_priv(sch);
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sfq_index d = q->max_depth;
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struct sk_buff *skb;
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unsigned int len;
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/* Queue is full! Find the longest slot and
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drop a packet from it */
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if (d > 1) {
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sfq_index x = q->dep[d+SFQ_DEPTH].next;
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skb = q->qs[x].prev;
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len = skb->len;
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__skb_unlink(skb, &q->qs[x]);
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kfree_skb(skb);
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sfq_dec(q, x);
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sch->q.qlen--;
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sch->qstats.drops++;
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return len;
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}
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if (d == 1) {
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/* It is difficult to believe, but ALL THE SLOTS HAVE LENGTH 1. */
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d = q->next[q->tail];
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q->next[q->tail] = q->next[d];
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q->allot[q->next[d]] += q->quantum;
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skb = q->qs[d].prev;
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len = skb->len;
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__skb_unlink(skb, &q->qs[d]);
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kfree_skb(skb);
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sfq_dec(q, d);
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sch->q.qlen--;
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q->ht[q->hash[d]] = SFQ_DEPTH;
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sch->qstats.drops++;
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return len;
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}
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return 0;
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}
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static int
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sfq_enqueue(struct sk_buff *skb, struct Qdisc* sch)
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{
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struct sfq_sched_data *q = qdisc_priv(sch);
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unsigned hash = sfq_hash(q, skb);
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sfq_index x;
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x = q->ht[hash];
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if (x == SFQ_DEPTH) {
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q->ht[hash] = x = q->dep[SFQ_DEPTH].next;
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q->hash[x] = hash;
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}
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__skb_queue_tail(&q->qs[x], skb);
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sfq_inc(q, x);
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if (q->qs[x].qlen == 1) { /* The flow is new */
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if (q->tail == SFQ_DEPTH) { /* It is the first flow */
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q->tail = x;
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q->next[x] = x;
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q->allot[x] = q->quantum;
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} else {
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q->next[x] = q->next[q->tail];
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q->next[q->tail] = x;
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q->tail = x;
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}
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}
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if (++sch->q.qlen < q->limit-1) {
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sch->bstats.bytes += skb->len;
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sch->bstats.packets++;
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return 0;
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}
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sfq_drop(sch);
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return NET_XMIT_CN;
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}
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static int
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sfq_requeue(struct sk_buff *skb, struct Qdisc* sch)
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{
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struct sfq_sched_data *q = qdisc_priv(sch);
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unsigned hash = sfq_hash(q, skb);
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sfq_index x;
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x = q->ht[hash];
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if (x == SFQ_DEPTH) {
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q->ht[hash] = x = q->dep[SFQ_DEPTH].next;
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q->hash[x] = hash;
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}
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__skb_queue_head(&q->qs[x], skb);
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sfq_inc(q, x);
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if (q->qs[x].qlen == 1) { /* The flow is new */
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if (q->tail == SFQ_DEPTH) { /* It is the first flow */
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q->tail = x;
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q->next[x] = x;
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q->allot[x] = q->quantum;
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} else {
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q->next[x] = q->next[q->tail];
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q->next[q->tail] = x;
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q->tail = x;
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}
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}
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if (++sch->q.qlen < q->limit - 1) {
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sch->qstats.requeues++;
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return 0;
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}
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sch->qstats.drops++;
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sfq_drop(sch);
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return NET_XMIT_CN;
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}
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static struct sk_buff *
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sfq_dequeue(struct Qdisc* sch)
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{
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struct sfq_sched_data *q = qdisc_priv(sch);
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struct sk_buff *skb;
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sfq_index a, old_a;
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/* No active slots */
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if (q->tail == SFQ_DEPTH)
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return NULL;
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a = old_a = q->next[q->tail];
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/* Grab packet */
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skb = __skb_dequeue(&q->qs[a]);
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sfq_dec(q, a);
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sch->q.qlen--;
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/* Is the slot empty? */
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if (q->qs[a].qlen == 0) {
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q->ht[q->hash[a]] = SFQ_DEPTH;
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a = q->next[a];
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if (a == old_a) {
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q->tail = SFQ_DEPTH;
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return skb;
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}
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q->next[q->tail] = a;
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q->allot[a] += q->quantum;
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} else if ((q->allot[a] -= skb->len) <= 0) {
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q->tail = a;
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a = q->next[a];
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q->allot[a] += q->quantum;
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}
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return skb;
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}
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static void
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sfq_reset(struct Qdisc* sch)
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{
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struct sk_buff *skb;
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while ((skb = sfq_dequeue(sch)) != NULL)
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kfree_skb(skb);
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}
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static void sfq_perturbation(unsigned long arg)
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{
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struct Qdisc *sch = (struct Qdisc*)arg;
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struct sfq_sched_data *q = qdisc_priv(sch);
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|
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q->perturbation = net_random()&0x1F;
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|
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if (q->perturb_period) {
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q->perturb_timer.expires = jiffies + q->perturb_period;
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add_timer(&q->perturb_timer);
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}
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}
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static int sfq_change(struct Qdisc *sch, struct rtattr *opt)
|
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{
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struct sfq_sched_data *q = qdisc_priv(sch);
|
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struct tc_sfq_qopt *ctl = RTA_DATA(opt);
|
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if (opt->rta_len < RTA_LENGTH(sizeof(*ctl)))
|
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return -EINVAL;
|
||||
|
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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);
|
||||
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||||
while (sch->q.qlen >= q->limit-1)
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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");
|
||||
Reference in New Issue
Block a user