[PATCH net-next-2.6 v3] net_sched: SFB flow scheduler

Eric Dumazet
2011-02-23T15:14:58Z

Hi David & Juliusz

Here is v3 of SFB. (previous ones were from Juliusz)

Thanks

[PATCH net-next-2.6 v3] net_sched: SFB flow scheduler

This is the Stochastic Fair Blue scheduler, based on work from :

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

This implementation is based on work done by Juliusz Chroboczek

General SFB algorithm can be found in figure 14, page 15:

B[l][n] : L x N array of bins (L levels, N bins per level)
enqueue()
Calculate hash function values h{0}, h{1}, .. h{L-1}
Update bins at each level
for i = 0 to L - 1
if (B[i][h{i}].qlen > bin_size)
B[i][h{i}].pm += delta;
else if (B[i][h{i}].qlen == 0)
B[i][h{i}].pm -= delta;
pmin = min(B[0][h{0}].pm ... B[L-1][h{L-1}].pm);
if (pmin == 1.0)
ratelimit();
else
mark/drop with probabilty pmin;

I did the adaptation of Juliusz code to meet current kernel standards,
and various changes to address previous comments :

http://thread.gmane.org/gmane.linux.network/90225
http://thread.gmane.org/gmane.linux.network/90375

Default flow classifier is the rxhash introduced by RPS in 2.6.35, but
we can use an external flow classifier if wanted.

tc qdisc add dev $IFB parent 1:11 handle 11: \
est 0.5sec 2sec sfb limit 128

tc filter add dev $DEV protocol ip parent 11: handle 3 \
flow hash keys dst divisor 1024

Notes:

1) SFB default child qdisc is pfifo_fast. It can be changed by another
qdisc but a child qdisc MUST not drop a packet previously queued. This
is because SFB needs to handle a dequeued packet in order to maintain
its virtual queue states. pfifo_head_drop or CHOKe should not be used.

2) I added one field in qdisc_skb_cb because SFB needs to remember the
hash/classid of an skb to decrement virtual queue lengthes at dequeue()
time.

3) ECN is enabled by default, unlike RED/CHOKe/GRED

With help from Patrick McHardy & Andi Kleen

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
CC: Juliusz Chroboczek <Juliusz.Chroboczek@pps.jussieu.fr>
CC: Stephen Hemminger <shemminger@vyatta.com>
CC: Patrick McHardy <kaber@trash.net>
CC: Andi Kleen <andi@firstfloor.org>
CC: John W. Linville <linville@tuxdriver.com>
---
include/linux/pkt_sched.h | 38 +
include/net/sch_generic.h | 1
net/sched/Kconfig | 11
net/sched/Makefile | 1
net/sched/sch_sfb.c | 696 ++++++++++++++++++++++++++++++++++++
5 files changed, 747 insertions(+)

diff --git a/include/linux/pkt_sched.h b/include/linux/pkt_sched.h
index d4bb6f5..629a8b0 100644
--- a/include/linux/pkt_sched.h
+++ b/include/linux/pkt_sched.h
@@ -522,4 +522,42 @@ struct tc_mqprio_qopt {
__u16 offset[TC_QOPT_MAX_QUEUE];
};

+/* SFB */
+
+enum {
+ TCA_SFB_UNSPEC,
+ TCA_SFB_PARMS,
+ __TCA_SFB_MAX,
+};
+
+#define TCA_SFB_MAX (__TCA_SFB_MAX - 1)
+
+/*
+ * Note: increment, decrement are Q0.16 fixed-point values.
+ */
+struct tc_sfb_qopt {
+ __u32 rehash_interval; /* delay between hash flip, in seconds */
+ __u32 db_interval; /* double buffering interval in seconds (db_interval < rehash_interval) */
+ __u32 max; /* max len of qlen_min */
+ __u32 target; /* bin_size */
+ __u32 increment; /* delta, (d1 in Blue) */
+ __u32 decrement; /* delta, (d2 in Blue) */
+ __u32 limit; /* max SFB queue length */
+ __u32 penalty_rate;
+ __u32 penalty_burst;
+};
+
+struct tc_sfb_xstats {
+ __u32 earlydrop;
+ __u32 penaltydrop;
+ __u32 bucketdrop;
+ __u32 queuedrop;
+ __u32 childdrop; /* drops in child qdisc */
+ __u32 marked;
+ __u32 maxqlen;
+ __u32 maxprob;
+};
+
+#define SFB_MAX_PROB 0xFFFF
+
#endif
diff --git a/include/net/sch_generic.h b/include/net/sch_generic.h
index 16626a0..f40d32e 100644
--- a/include/net/sch_generic.h
+++ b/include/net/sch_generic.h
@@ -218,6 +218,7 @@ struct tcf_proto {

struct qdisc_skb_cb {
unsigned int pkt_len;
+ unsigned int sfb_classid;
char data[];
};

diff --git a/net/sched/Kconfig b/net/sched/Kconfig
index 8c19b6e..a7a5583 100644
--- a/net/sched/Kconfig
+++ b/net/sched/Kconfig
@@ -126,6 +126,17 @@ config NET_SCH_RED
To compile this code as a module, choose M here: the
module will be called sch_red.

+config NET_SCH_SFB
+ tristate "Stochastic Fair Blue (SFB)"
+ ---help---
+ Say Y here if you want to use the Stochastic Fair Blue (SFB)
+ packet scheduling algorithm.
+
+ See the top of <file:net/sched/sch_sfb.c> for more details.
+
+ To compile this code as a module, choose M here: the
+ module will be called sch_sfb.
+
config NET_SCH_SFQ
tristate "Stochastic Fairness Queueing (SFQ)"
---help---
diff --git a/net/sched/Makefile b/net/sched/Makefile
index 06c6cdf..2e77b8d 100644
--- a/net/sched/Makefile
+++ b/net/sched/Makefile
@@ -24,6 +24,7 @@ obj-$(CONFIG_NET_SCH_RED) += sch_red.o
obj-$(CONFIG_NET_SCH_GRED) += sch_gred.o
obj-$(CONFIG_NET_SCH_INGRESS) += sch_ingress.o
obj-$(CONFIG_NET_SCH_DSMARK) += sch_dsmark.o
+obj-$(CONFIG_NET_SCH_SFB) += sch_sfb.o
obj-$(CONFIG_NET_SCH_SFQ) += sch_sfq.o
obj-$(CONFIG_NET_SCH_TBF) += sch_tbf.o
obj-$(CONFIG_NET_SCH_TEQL) += sch_teql.o
diff --git a/net/sched/sch_sfb.c b/net/sched/sch_sfb.c
new file mode 100644
index 0000000..b7f1c6e
--- /dev/null
+++ b/net/sched/sch_sfb.c
@@ -0,0 +1,696 @@
+/*
+ * 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 pm; /* 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 db_interval; /* interval of double buffering */
+ u32 max;
+ u32 target; /* bin_size */
+ 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;
+};
+
+/*
+ * If using 'internal' SFB flow classifier, sfb_classid is skb rxhash
+ * If using external classifier, sfb_classid contains the classid.
+ */
+static u32 sfb_hash(const struct sk_buff *skb, u32 slot,
+ struct sfb_sched_data *q)
+{
+ return jhash_1word(qdisc_skb_cb(skb)->sfb_classid,
+ q->bins[slot].perturbation);
+}
+
+/* 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(u32 hashes[2], struct sfb_sched_data *q)
+{
+ u32 slot = q->slot;
+
+ increment_one_qlen(hashes[slot], slot, q);
+ if (q->double_buffering) {
+ slot ^= 1;
+ increment_one_qlen(hashes[slot], slot, 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(struct sk_buff *skb, struct sfb_sched_data *q)
+{
+ u32 slot = q->slot;
+ u32 sfbhash = sfb_hash(skb, slot, q);
+
+ decrement_one_qlen(sfbhash, slot, q);
+ if (q->double_buffering) {
+ slot ^= 1;
+ sfbhash = sfb_hash(skb, slot, q);
+ decrement_one_qlen(sfbhash, slot, q);
+ }
+}
+
+static void decrement_prob(struct sfb_bucket *b, struct sfb_sched_data *q)
+{
+ b->pm = prob_minus(b->pm, q->decrement);
+}
+
+static void increment_prob(struct sfb_bucket *b, struct sfb_sched_data *q)
+{
+ b->pm = prob_plus(b->pm, q->increment);
+}
+
+static void sfb_zero_all_buckets(int slot, struct sfb_sched_data *q)
+{
+ memset(&q->bins[slot], 0, sizeof(q->bins[slot]));
+}
+
+/*
+ * compute max qlen and max pm
+ */
+static u32 sfb_compute_qlen(u32 *prob_r, const struct sfb_sched_data *q)
+{
+ int i;
+ u32 qlen = 0, prob = 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;
+ if (prob < b->pm)
+ prob = b->pm;
+ b++;
+ }
+ *prob_r = prob;
+ return qlen;
+}
+
+
+static void sfb_init_perturbation(u32 slot, struct sfb_sched_data *q)
+{
+ q->bins[slot].perturbation = net_random();
+}
+
+static void sfb_swap_buffers(struct sfb_sched_data *q)
+{
+ sfb_zero_all_buckets(q->slot, 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)
+{
+ 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
+ qdisc_skb_cb(skb)->sfb_classid = 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 minprob = SFB_MAX_PROB;
+ u32 minqlen = ~0;
+ u32 r, slot, hashes[2], sfbhash;
+ int ret = NET_XMIT_SUCCESS | __NET_XMIT_BYPASS;
+
+ if (q->filter_list) {
+ /* If using external classifiers, get result and record it. */
+ if (!sfb_classify(skb, q, &ret))
+ goto other_drop;
+ } else {
+ qdisc_skb_cb(skb)->sfb_classid = skb_get_rxhash(skb);
+ }
+
+ if (q->rehash_interval > 0) {
+ unsigned long limit = q->rehash_time + q->rehash_interval;
+
+ if (unlikely(time_after(jiffies, limit))) {
+ sfb_swap_buffers(q);
+ q->rehash_time = jiffies;
+ } else if (unlikely(!q->double_buffering && q->db_interval > 0 &&
+ time_after(jiffies, limit - q->db_interval))) {
+ q->double_buffering = true;
+ }
+ }
+
+ slot = q->slot;
+
+ hashes[slot] = sfbhash = sfb_hash(skb, slot, q);
+ 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 (unlikely(b->qlen >= q->target))
+ increment_prob(b, q);
+ if (minqlen > b->qlen)
+ minqlen = b->qlen;
+ if (minprob > b->pm)
+ minprob = b->pm;
+ }
+
+ if (q->double_buffering) {
+ slot ^= 1;
+ hashes[slot] = sfbhash = sfb_hash(skb, slot, q);
+ 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 (unlikely(b->qlen >= q->target))
+ increment_prob(b, q);
+ }
+ }
+
+ 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(minprob >= SFB_MAX_PROB)) {
+ /* Inelastic flow */
+ 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 < minprob)) {
+ if (unlikely(minprob > 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 < (minprob - 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(hashes, 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(0, q);
+ sfb_zero_all_buckets(1, 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 int sfb_change(struct Qdisc *sch, struct nlattr *opt)
+{
+ struct sfb_sched_data *q = qdisc_priv(sch);
+ struct Qdisc *child = NULL;
+ struct nlattr *tb[TCA_SFB_MAX + 1];
+ struct tc_sfb_qopt *ctl;
+ u32 rehash_interval, db_interval;
+ u32 limit;
+ u32 max, target;
+ u32 increment, decrement;
+ u32 penalty_rate, penalty_burst;
+ int err;
+
+ if (opt == NULL) {
+ rehash_interval = 600;
+ db_interval = 60;
+ limit = 0;
+ max = 25;
+ target = 20;
+ increment = (SFB_MAX_PROB + 500) / 1000; /* 0.1 % */
+ decrement = (SFB_MAX_PROB + 3000) / 6000;
+ penalty_rate = 10;
+ penalty_burst = 20;
+ } else {
+ 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]);
+
+ rehash_interval = ctl->rehash_interval;
+ db_interval = ctl->db_interval;
+ limit = ctl->limit;
+ max = ctl->max;
+ target = ctl->target;
+ increment = ctl->increment;
+ decrement = ctl->decrement;
+ penalty_rate = ctl->penalty_rate;
+ penalty_burst = ctl->penalty_burst;
+ }
+
+ if (limit == 0)
+ limit = qdisc_dev(sch)->tx_queue_len;
+ if (limit == 0)
+ limit = 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 = (unsigned long)rehash_interval * HZ;
+ q->db_interval = (unsigned long)db_interval * HZ;
+ q->rehash_time = jiffies;
+ q->limit = limit;
+ q->increment = increment;
+ q->decrement = decrement;
+ q->max = max;
+ q->target = target;
+ q->penalty_rate = penalty_rate;
+ q->penalty_burst = penalty_burst;
+ q->tokens_avail = penalty_burst;
+ q->token_time = jiffies;
+
+ q->slot = 0;
+ q->double_buffering = false;
+ sfb_zero_all_buckets(0, q);
+ sfb_zero_all_buckets(1, q);
+ sfb_init_perturbation(0, 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 = q->rehash_interval / HZ,
+ .db_interval = q->db_interval / HZ,
+ .limit = q->limit,
+ .max = q->max,
+ .target = q->target,
+ .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, 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,
+};
+
+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_LICENSE("GPL");