--- /dev/null
+/*
+ * net/sched/sch_sfb.c Stochastic Fair Blue
+ *
+ * Copyright (c) 2008-2011 Juliusz Chroboczek <jch@pps.jussieu.fr>
+ * Copyright (c) 2011 Eric Dumazet <eric.dumazet@gmail.com>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * version 2 as published by the Free Software Foundation.
+ *
+ * W. Feng, D. Kandlur, D. Saha, K. Shin. Blue:
+ * A New Class of Active Queue Management Algorithms.
+ * U. Michigan CSE-TR-387-99, April 1999.
+ *
+ * http://www.thefengs.com/wuchang/blue/CSE-TR-387-99.pdf
+ *
+ */
+
+#include <linux/module.h>
+#include <linux/types.h>
+#include <linux/kernel.h>
+#include <linux/errno.h>
+#include <linux/skbuff.h>
+#include <linux/random.h>
+#include <linux/jhash.h>
+#include <net/ip.h>
+#include <net/pkt_sched.h>
+#include <net/inet_ecn.h>
+
+/*
+ * SFB uses two B[l][n] : L x N arrays of bins (L levels, N bins per level)
+ * This implementation uses L = 8 and N = 16
+ * This permits us to split one 32bit hash (provided per packet by rxhash or
+ * external classifier) into 8 subhashes of 4 bits.
+ */
+#define SFB_BUCKET_SHIFT 4
+#define SFB_NUMBUCKETS (1 << SFB_BUCKET_SHIFT) /* N bins per Level */
+#define SFB_BUCKET_MASK (SFB_NUMBUCKETS - 1)
+#define SFB_LEVELS (32 / SFB_BUCKET_SHIFT) /* L */
+
+/* SFB algo uses a virtual queue, named "bin" */
+struct sfb_bucket {
+ u16 qlen; /* length of virtual queue */
+ u16 p_mark; /* marking probability */
+};
+
+/* We use a double buffering right before hash change
+ * (Section 4.4 of SFB reference : moving hash functions)
+ */
+struct sfb_bins {
+ u32 perturbation; /* jhash perturbation */
+ struct sfb_bucket bins[SFB_LEVELS][SFB_NUMBUCKETS];
+};
+
+struct sfb_sched_data {
+ struct Qdisc *qdisc;
+ struct tcf_proto *filter_list;
+ unsigned long rehash_interval;
+ unsigned long warmup_time; /* double buffering warmup time in jiffies */
+ u32 max;
+ u32 bin_size; /* maximum queue length per bin */
+ u32 increment; /* d1 */
+ u32 decrement; /* d2 */
+ u32 limit; /* HARD maximal queue length */
+ u32 penalty_rate;
+ u32 penalty_burst;
+ u32 tokens_avail;
+ unsigned long rehash_time;
+ unsigned long token_time;
+
+ u8 slot; /* current active bins (0 or 1) */
+ bool double_buffering;
+ struct sfb_bins bins[2];
+
+ struct {
+ u32 earlydrop;
+ u32 penaltydrop;
+ u32 bucketdrop;
+ u32 queuedrop;
+ u32 childdrop; /* drops in child qdisc */
+ u32 marked; /* ECN mark */
+ } stats;
+};
+
+/*
+ * Each queued skb might be hashed on one or two bins
+ * We store in skb_cb the two hash values.
+ * (A zero value means double buffering was not used)
+ */
+struct sfb_skb_cb {
+ u32 hashes[2];
+};
+
+static inline struct sfb_skb_cb *sfb_skb_cb(const struct sk_buff *skb)
+{
+ BUILD_BUG_ON(sizeof(skb->cb) <
+ sizeof(struct qdisc_skb_cb) + sizeof(struct sfb_skb_cb));
+ return (struct sfb_skb_cb *)qdisc_skb_cb(skb)->data;
+}
+
+/*
+ * If using 'internal' SFB flow classifier, hash comes from skb rxhash
+ * If using external classifier, hash comes from the classid.
+ */
+static u32 sfb_hash(const struct sk_buff *skb, u32 slot)
+{
+ return sfb_skb_cb(skb)->hashes[slot];
+}
+
+/* Probabilities are coded as Q0.16 fixed-point values,
+ * with 0xFFFF representing 65535/65536 (almost 1.0)
+ * Addition and subtraction are saturating in [0, 65535]
+ */
+static u32 prob_plus(u32 p1, u32 p2)
+{
+ u32 res = p1 + p2;
+
+ return min_t(u32, res, SFB_MAX_PROB);
+}
+
+static u32 prob_minus(u32 p1, u32 p2)
+{
+ return p1 > p2 ? p1 - p2 : 0;
+}
+
+static void increment_one_qlen(u32 sfbhash, u32 slot, struct sfb_sched_data *q)
+{
+ int i;
+ struct sfb_bucket *b = &q->bins[slot].bins[0][0];
+
+ for (i = 0; i < SFB_LEVELS; i++) {
+ u32 hash = sfbhash & SFB_BUCKET_MASK;
+
+ sfbhash >>= SFB_BUCKET_SHIFT;
+ if (b[hash].qlen < 0xFFFF)
+ b[hash].qlen++;
+ b += SFB_NUMBUCKETS; /* next level */
+ }
+}
+
+static void increment_qlen(const struct sk_buff *skb, struct sfb_sched_data *q)
+{
+ u32 sfbhash;
+
+ sfbhash = sfb_hash(skb, 0);
+ if (sfbhash)
+ increment_one_qlen(sfbhash, 0, q);
+
+ sfbhash = sfb_hash(skb, 1);
+ if (sfbhash)
+ increment_one_qlen(sfbhash, 1, q);
+}
+
+static void decrement_one_qlen(u32 sfbhash, u32 slot,
+ struct sfb_sched_data *q)
+{
+ int i;
+ struct sfb_bucket *b = &q->bins[slot].bins[0][0];
+
+ for (i = 0; i < SFB_LEVELS; i++) {
+ u32 hash = sfbhash & SFB_BUCKET_MASK;
+
+ sfbhash >>= SFB_BUCKET_SHIFT;
+ if (b[hash].qlen > 0)
+ b[hash].qlen--;
+ b += SFB_NUMBUCKETS; /* next level */
+ }
+}
+
+static void decrement_qlen(const struct sk_buff *skb, struct sfb_sched_data *q)
+{
+ u32 sfbhash;
+
+ sfbhash = sfb_hash(skb, 0);
+ if (sfbhash)
+ decrement_one_qlen(sfbhash, 0, q);
+
+ sfbhash = sfb_hash(skb, 1);
+ if (sfbhash)
+ decrement_one_qlen(sfbhash, 1, q);
+}
+
+static void decrement_prob(struct sfb_bucket *b, struct sfb_sched_data *q)
+{
+ b->p_mark = prob_minus(b->p_mark, q->decrement);
+}
+
+static void increment_prob(struct sfb_bucket *b, struct sfb_sched_data *q)
+{
+ b->p_mark = prob_plus(b->p_mark, q->increment);
+}
+
+static void sfb_zero_all_buckets(struct sfb_sched_data *q)
+{
+ memset(&q->bins, 0, sizeof(q->bins));
+}
+
+/*
+ * compute max qlen, max p_mark, and avg p_mark
+ */
+static u32 sfb_compute_qlen(u32 *prob_r, u32 *avgpm_r, const struct sfb_sched_data *q)
+{
+ int i;
+ u32 qlen = 0, prob = 0, totalpm = 0;
+ const struct sfb_bucket *b = &q->bins[q->slot].bins[0][0];
+
+ for (i = 0; i < SFB_LEVELS * SFB_NUMBUCKETS; i++) {
+ if (qlen < b->qlen)
+ qlen = b->qlen;
+ totalpm += b->p_mark;
+ if (prob < b->p_mark)
+ prob = b->p_mark;
+ b++;
+ }
+ *prob_r = prob;
+ *avgpm_r = totalpm / (SFB_LEVELS * SFB_NUMBUCKETS);
+ return qlen;
+}
+
+
+static void sfb_init_perturbation(u32 slot, struct sfb_sched_data *q)
+{
+ q->bins[slot].perturbation = net_random();
+}
+
+static void sfb_swap_slot(struct sfb_sched_data *q)
+{
+ sfb_init_perturbation(q->slot, q);
+ q->slot ^= 1;
+ q->double_buffering = false;
+}
+
+/* Non elastic flows are allowed to use part of the bandwidth, expressed
+ * in "penalty_rate" packets per second, with "penalty_burst" burst
+ */
+static bool sfb_rate_limit(struct sk_buff *skb, struct sfb_sched_data *q)
+{
+ if (q->penalty_rate == 0 || q->penalty_burst == 0)
+ return true;
+
+ if (q->tokens_avail < 1) {
+ unsigned long age = min(10UL * HZ, jiffies - q->token_time);
+
+ q->tokens_avail = (age * q->penalty_rate) / HZ;
+ if (q->tokens_avail > q->penalty_burst)
+ q->tokens_avail = q->penalty_burst;
+ q->token_time = jiffies;
+ if (q->tokens_avail < 1)
+ return true;
+ }
+
+ q->tokens_avail--;
+ return false;
+}
+
+static bool sfb_classify(struct sk_buff *skb, struct sfb_sched_data *q,
+ int *qerr, u32 *salt)
+{
+ struct tcf_result res;
+ int result;
+
+ 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 false;
+ }
+#endif
+ *salt = TC_H_MIN(res.classid);
+ return true;
+ }
+ return false;
+}
+
+static int sfb_enqueue(struct sk_buff *skb, struct Qdisc *sch)
+{
+
+ struct sfb_sched_data *q = qdisc_priv(sch);
+ struct Qdisc *child = q->qdisc;
+ int i;
+ u32 p_min = ~0;
+ u32 minqlen = ~0;
+ u32 r, slot, salt, sfbhash;
+ int ret = NET_XMIT_SUCCESS | __NET_XMIT_BYPASS;
+
+ if (q->rehash_interval > 0) {
+ unsigned long limit = q->rehash_time + q->rehash_interval;
+
+ if (unlikely(time_after(jiffies, limit))) {
+ sfb_swap_slot(q);
+ q->rehash_time = jiffies;
+ } else if (unlikely(!q->double_buffering && q->warmup_time > 0 &&
+ time_after(jiffies, limit - q->warmup_time))) {
+ q->double_buffering = true;
+ }
+ }
+
+ if (q->filter_list) {
+ /* If using external classifiers, get result and record it. */
+ if (!sfb_classify(skb, q, &ret, &salt))
+ goto other_drop;
+ } else {
+ salt = skb_get_rxhash(skb);
+ }
+
+ slot = q->slot;
+
+ sfbhash = jhash_1word(salt, q->bins[slot].perturbation);
+ if (!sfbhash)
+ sfbhash = 1;
+ sfb_skb_cb(skb)->hashes[slot] = sfbhash;
+
+ for (i = 0; i < SFB_LEVELS; i++) {
+ u32 hash = sfbhash & SFB_BUCKET_MASK;
+ struct sfb_bucket *b = &q->bins[slot].bins[i][hash];
+
+ sfbhash >>= SFB_BUCKET_SHIFT;
+ if (b->qlen == 0)
+ decrement_prob(b, q);
+ else if (b->qlen >= q->bin_size)
+ increment_prob(b, q);
+ if (minqlen > b->qlen)
+ minqlen = b->qlen;
+ if (p_min > b->p_mark)
+ p_min = b->p_mark;
+ }
+
+ slot ^= 1;
+ sfb_skb_cb(skb)->hashes[slot] = 0;
+
+ if (unlikely(minqlen >= q->max || sch->q.qlen >= q->limit)) {
+ sch->qstats.overlimits++;
+ if (minqlen >= q->max)
+ q->stats.bucketdrop++;
+ else
+ q->stats.queuedrop++;
+ goto drop;
+ }
+
+ if (unlikely(p_min >= SFB_MAX_PROB)) {
+ /* Inelastic flow */
+ if (q->double_buffering) {
+ sfbhash = jhash_1word(salt, q->bins[slot].perturbation);
+ if (!sfbhash)
+ sfbhash = 1;
+ sfb_skb_cb(skb)->hashes[slot] = sfbhash;
+
+ for (i = 0; i < SFB_LEVELS; i++) {
+ u32 hash = sfbhash & SFB_BUCKET_MASK;
+ struct sfb_bucket *b = &q->bins[slot].bins[i][hash];
+
+ sfbhash >>= SFB_BUCKET_SHIFT;
+ if (b->qlen == 0)
+ decrement_prob(b, q);
+ else if (b->qlen >= q->bin_size)
+ increment_prob(b, q);
+ }
+ }
+ if (sfb_rate_limit(skb, q)) {
+ sch->qstats.overlimits++;
+ q->stats.penaltydrop++;
+ goto drop;
+ }
+ goto enqueue;
+ }
+
+ r = net_random() & SFB_MAX_PROB;
+
+ if (unlikely(r < p_min)) {
+ if (unlikely(p_min > SFB_MAX_PROB / 2)) {
+ /* If we're marking that many packets, then either
+ * this flow is unresponsive, or we're badly congested.
+ * In either case, we want to start dropping packets.
+ */
+ if (r < (p_min - SFB_MAX_PROB / 2) * 2) {
+ q->stats.earlydrop++;
+ goto drop;
+ }
+ }
+ if (INET_ECN_set_ce(skb)) {
+ q->stats.marked++;
+ } else {
+ q->stats.earlydrop++;
+ goto drop;
+ }
+ }
+
+enqueue:
+ ret = qdisc_enqueue(skb, child);
+ if (likely(ret == NET_XMIT_SUCCESS)) {
+ sch->q.qlen++;
+ increment_qlen(skb, q);
+ } else if (net_xmit_drop_count(ret)) {
+ q->stats.childdrop++;
+ sch->qstats.drops++;
+ }
+ return ret;
+
+drop:
+ qdisc_drop(skb, sch);
+ return NET_XMIT_CN;
+other_drop:
+ if (ret & __NET_XMIT_BYPASS)
+ sch->qstats.drops++;
+ kfree_skb(skb);
+ return ret;
+}
+
+static struct sk_buff *sfb_dequeue(struct Qdisc *sch)
+{
+ struct sfb_sched_data *q = qdisc_priv(sch);
+ struct Qdisc *child = q->qdisc;
+ struct sk_buff *skb;
+
+ skb = child->dequeue(q->qdisc);
+
+ if (skb) {
+ qdisc_bstats_update(sch, skb);
+ sch->q.qlen--;
+ decrement_qlen(skb, q);
+ }
+
+ return skb;
+}
+
+static struct sk_buff *sfb_peek(struct Qdisc *sch)
+{
+ struct sfb_sched_data *q = qdisc_priv(sch);
+ struct Qdisc *child = q->qdisc;
+
+ return child->ops->peek(child);
+}
+
+/* No sfb_drop -- impossible since the child doesn't return the dropped skb. */
+
+static void sfb_reset(struct Qdisc *sch)
+{
+ struct sfb_sched_data *q = qdisc_priv(sch);
+
+ qdisc_reset(q->qdisc);
+ sch->q.qlen = 0;
+ q->slot = 0;
+ q->double_buffering = false;
+ sfb_zero_all_buckets(q);
+ sfb_init_perturbation(0, q);
+}
+
+static void sfb_destroy(struct Qdisc *sch)
+{
+ struct sfb_sched_data *q = qdisc_priv(sch);
+
+ tcf_destroy_chain(&q->filter_list);
+ qdisc_destroy(q->qdisc);
+}
+
+static const struct nla_policy sfb_policy[TCA_SFB_MAX + 1] = {
+ [TCA_SFB_PARMS] = { .len = sizeof(struct tc_sfb_qopt) },
+};
+
+static const struct tc_sfb_qopt sfb_default_ops = {
+ .rehash_interval = 600 * MSEC_PER_SEC,
+ .warmup_time = 60 * MSEC_PER_SEC,
+ .limit = 0,
+ .max = 25,
+ .bin_size = 20,
+ .increment = (SFB_MAX_PROB + 500) / 1000, /* 0.1 % */
+ .decrement = (SFB_MAX_PROB + 3000) / 6000,
+ .penalty_rate = 10,
+ .penalty_burst = 20,
+};
+
+static int sfb_change(struct Qdisc *sch, struct nlattr *opt)
+{
+ struct sfb_sched_data *q = qdisc_priv(sch);
+ struct Qdisc *child;
+ struct nlattr *tb[TCA_SFB_MAX + 1];
+ const struct tc_sfb_qopt *ctl = &sfb_default_ops;
+ u32 limit;
+ int err;
+
+ if (opt) {
+ err = nla_parse_nested(tb, TCA_SFB_MAX, opt, sfb_policy);
+ if (err < 0)
+ return -EINVAL;
+
+ if (tb[TCA_SFB_PARMS] == NULL)
+ return -EINVAL;
+
+ ctl = nla_data(tb[TCA_SFB_PARMS]);
+ }
+
+ limit = ctl->limit;
+ if (limit == 0)
+ limit = max_t(u32, qdisc_dev(sch)->tx_queue_len, 1);
+
+ child = fifo_create_dflt(sch, &pfifo_qdisc_ops, limit);
+ if (IS_ERR(child))
+ return PTR_ERR(child);
+
+ sch_tree_lock(sch);
+
+ qdisc_tree_decrease_qlen(q->qdisc, q->qdisc->q.qlen);
+ qdisc_destroy(q->qdisc);
+ q->qdisc = child;
+
+ q->rehash_interval = msecs_to_jiffies(ctl->rehash_interval);
+ q->warmup_time = msecs_to_jiffies(ctl->warmup_time);
+ q->rehash_time = jiffies;
+ q->limit = limit;
+ q->increment = ctl->increment;
+ q->decrement = ctl->decrement;
+ q->max = ctl->max;
+ q->bin_size = ctl->bin_size;
+ q->penalty_rate = ctl->penalty_rate;
+ q->penalty_burst = ctl->penalty_burst;
+ q->tokens_avail = ctl->penalty_burst;
+ q->token_time = jiffies;
+
+ q->slot = 0;
+ q->double_buffering = false;
+ sfb_zero_all_buckets(q);
+ sfb_init_perturbation(0, q);
+ sfb_init_perturbation(1, q);
+
+ sch_tree_unlock(sch);
+
+ return 0;
+}
+
+static int sfb_init(struct Qdisc *sch, struct nlattr *opt)
+{
+ struct sfb_sched_data *q = qdisc_priv(sch);
+
+ q->qdisc = &noop_qdisc;
+ return sfb_change(sch, opt);
+}
+
+static int sfb_dump(struct Qdisc *sch, struct sk_buff *skb)
+{
+ struct sfb_sched_data *q = qdisc_priv(sch);
+ struct nlattr *opts;
+ struct tc_sfb_qopt opt = {
+ .rehash_interval = jiffies_to_msecs(q->rehash_interval),
+ .warmup_time = jiffies_to_msecs(q->warmup_time),
+ .limit = q->limit,
+ .max = q->max,
+ .bin_size = q->bin_size,
+ .increment = q->increment,
+ .decrement = q->decrement,
+ .penalty_rate = q->penalty_rate,
+ .penalty_burst = q->penalty_burst,
+ };
+
+ sch->qstats.backlog = q->qdisc->qstats.backlog;
+ opts = nla_nest_start(skb, TCA_OPTIONS);
+ NLA_PUT(skb, TCA_SFB_PARMS, sizeof(opt), &opt);
+ return nla_nest_end(skb, opts);
+
+nla_put_failure:
+ nla_nest_cancel(skb, opts);
+ return -EMSGSIZE;
+}
+
+static int sfb_dump_stats(struct Qdisc *sch, struct gnet_dump *d)
+{
+ struct sfb_sched_data *q = qdisc_priv(sch);
+ struct tc_sfb_xstats st = {
+ .earlydrop = q->stats.earlydrop,
+ .penaltydrop = q->stats.penaltydrop,
+ .bucketdrop = q->stats.bucketdrop,
+ .queuedrop = q->stats.queuedrop,
+ .childdrop = q->stats.childdrop,
+ .marked = q->stats.marked,
+ };
+
+ st.maxqlen = sfb_compute_qlen(&st.maxprob, &st.avgprob, q);
+
+ return gnet_stats_copy_app(d, &st, sizeof(st));
+}
+
+static int sfb_dump_class(struct Qdisc *sch, unsigned long cl,
+ struct sk_buff *skb, struct tcmsg *tcm)
+{
+ return -ENOSYS;
+}
+
+static int sfb_graft(struct Qdisc *sch, unsigned long arg, struct Qdisc *new,
+ struct Qdisc **old)
+{
+ struct sfb_sched_data *q = qdisc_priv(sch);
+
+ if (new == NULL)
+ new = &noop_qdisc;
+
+ sch_tree_lock(sch);
+ *old = q->qdisc;
+ q->qdisc = new;
+ qdisc_tree_decrease_qlen(*old, (*old)->q.qlen);
+ qdisc_reset(*old);
+ sch_tree_unlock(sch);
+ return 0;
+}
+
+static struct Qdisc *sfb_leaf(struct Qdisc *sch, unsigned long arg)
+{
+ struct sfb_sched_data *q = qdisc_priv(sch);
+
+ return q->qdisc;
+}
+
+static unsigned long sfb_get(struct Qdisc *sch, u32 classid)
+{
+ return 1;
+}
+
+static void sfb_put(struct Qdisc *sch, unsigned long arg)
+{
+}
+
+static int sfb_change_class(struct Qdisc *sch, u32 classid, u32 parentid,
+ struct nlattr **tca, unsigned long *arg)
+{
+ return -ENOSYS;
+}
+
+static int sfb_delete(struct Qdisc *sch, unsigned long cl)
+{
+ return -ENOSYS;
+}
+
+static void sfb_walk(struct Qdisc *sch, struct qdisc_walker *walker)
+{
+ if (!walker->stop) {
+ if (walker->count >= walker->skip)
+ if (walker->fn(sch, 1, walker) < 0) {
+ walker->stop = 1;
+ return;
+ }
+ walker->count++;
+ }
+}
+
+static struct tcf_proto **sfb_find_tcf(struct Qdisc *sch, unsigned long cl)
+{
+ struct sfb_sched_data *q = qdisc_priv(sch);
+
+ if (cl)
+ return NULL;
+ return &q->filter_list;
+}
+
+static unsigned long sfb_bind(struct Qdisc *sch, unsigned long parent,
+ u32 classid)
+{
+ return 0;
+}
+
+
+static const struct Qdisc_class_ops sfb_class_ops = {
+ .graft = sfb_graft,
+ .leaf = sfb_leaf,
+ .get = sfb_get,
+ .put = sfb_put,
+ .change = sfb_change_class,
+ .delete = sfb_delete,
+ .walk = sfb_walk,
+ .tcf_chain = sfb_find_tcf,
+ .bind_tcf = sfb_bind,
+ .unbind_tcf = sfb_put,
+ .dump = sfb_dump_class,
+};
+
+static struct Qdisc_ops sfb_qdisc_ops __read_mostly = {
+ .id = "sfb",
+ .priv_size = sizeof(struct sfb_sched_data),
+ .cl_ops = &sfb_class_ops,
+ .enqueue = sfb_enqueue,
+ .dequeue = sfb_dequeue,
+ .peek = sfb_peek,
+ .init = sfb_init,
+ .reset = sfb_reset,
+ .destroy = sfb_destroy,
+ .change = sfb_change,
+ .dump = sfb_dump,
+ .dump_stats = sfb_dump_stats,
+ .owner = THIS_MODULE,
+};
+
+static int __init sfb_module_init(void)
+{
+ return register_qdisc(&sfb_qdisc_ops);
+}
+
+static void __exit sfb_module_exit(void)
+{
+ unregister_qdisc(&sfb_qdisc_ops);
+}
+
+module_init(sfb_module_init)
+module_exit(sfb_module_exit)
+
+MODULE_DESCRIPTION("Stochastic Fair Blue queue discipline");
+MODULE_AUTHOR("Juliusz Chroboczek");
+MODULE_AUTHOR("Eric Dumazet");
+MODULE_LICENSE("GPL");
projects / karo-tx-linux.git / commitdiff