summaryrefslogtreecommitdiffstats
path: root/net/sched/sch_tbf.c
diff options
context:
space:
mode:
Diffstat (limited to 'net/sched/sch_tbf.c')
-rw-r--r--net/sched/sch_tbf.c563
1 files changed, 563 insertions, 0 deletions
diff --git a/net/sched/sch_tbf.c b/net/sched/sch_tbf.c
new file mode 100644
index 000000000..dd29de141
--- /dev/null
+++ b/net/sched/sch_tbf.c
@@ -0,0 +1,563 @@
+/*
+ * net/sched/sch_tbf.c Token Bucket Filter queue.
+ *
+ * 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>
+ * Dmitry Torokhov <dtor@mail.ru> - allow attaching inner qdiscs -
+ * original idea by Martin Devera
+ *
+ */
+
+#include <linux/module.h>
+#include <linux/types.h>
+#include <linux/kernel.h>
+#include <linux/string.h>
+#include <linux/errno.h>
+#include <linux/skbuff.h>
+#include <net/netlink.h>
+#include <net/sch_generic.h>
+#include <net/pkt_sched.h>
+
+
+/* Simple Token Bucket Filter.
+ =======================================
+
+ SOURCE.
+ -------
+
+ None.
+
+ Description.
+ ------------
+
+ A data flow obeys TBF with rate R and depth B, if for any
+ time interval t_i...t_f the number of transmitted bits
+ does not exceed B + R*(t_f-t_i).
+
+ Packetized version of this definition:
+ The sequence of packets of sizes s_i served at moments t_i
+ obeys TBF, if for any i<=k:
+
+ s_i+....+s_k <= B + R*(t_k - t_i)
+
+ Algorithm.
+ ----------
+
+ Let N(t_i) be B/R initially and N(t) grow continuously with time as:
+
+ N(t+delta) = min{B/R, N(t) + delta}
+
+ If the first packet in queue has length S, it may be
+ transmitted only at the time t_* when S/R <= N(t_*),
+ and in this case N(t) jumps:
+
+ N(t_* + 0) = N(t_* - 0) - S/R.
+
+
+
+ Actually, QoS requires two TBF to be applied to a data stream.
+ One of them controls steady state burst size, another
+ one with rate P (peak rate) and depth M (equal to link MTU)
+ limits bursts at a smaller time scale.
+
+ It is easy to see that P>R, and B>M. If P is infinity, this double
+ TBF is equivalent to a single one.
+
+ When TBF works in reshaping mode, latency is estimated as:
+
+ lat = max ((L-B)/R, (L-M)/P)
+
+
+ NOTES.
+ ------
+
+ If TBF throttles, it starts a watchdog timer, which will wake it up
+ when it is ready to transmit.
+ Note that the minimal timer resolution is 1/HZ.
+ If no new packets arrive during this period,
+ or if the device is not awaken by EOI for some previous packet,
+ TBF can stop its activity for 1/HZ.
+
+
+ This means, that with depth B, the maximal rate is
+
+ R_crit = B*HZ
+
+ F.e. for 10Mbit ethernet and HZ=100 the minimal allowed B is ~10Kbytes.
+
+ Note that the peak rate TBF is much more tough: with MTU 1500
+ P_crit = 150Kbytes/sec. So, if you need greater peak
+ rates, use alpha with HZ=1000 :-)
+
+ With classful TBF, limit is just kept for backwards compatibility.
+ It is passed to the default bfifo qdisc - if the inner qdisc is
+ changed the limit is not effective anymore.
+*/
+
+struct tbf_sched_data {
+/* Parameters */
+ u32 limit; /* Maximal length of backlog: bytes */
+ u32 max_size;
+ s64 buffer; /* Token bucket depth/rate: MUST BE >= MTU/B */
+ s64 mtu;
+ struct psched_ratecfg rate;
+ struct psched_ratecfg peak;
+
+/* Variables */
+ s64 tokens; /* Current number of B tokens */
+ s64 ptokens; /* Current number of P tokens */
+ s64 t_c; /* Time check-point */
+ struct Qdisc *qdisc; /* Inner qdisc, default - bfifo queue */
+ struct qdisc_watchdog watchdog; /* Watchdog timer */
+};
+
+
+/* Time to Length, convert time in ns to length in bytes
+ * to determinate how many bytes can be sent in given time.
+ */
+static u64 psched_ns_t2l(const struct psched_ratecfg *r,
+ u64 time_in_ns)
+{
+ /* The formula is :
+ * len = (time_in_ns * r->rate_bytes_ps) / NSEC_PER_SEC
+ */
+ u64 len = time_in_ns * r->rate_bytes_ps;
+
+ do_div(len, NSEC_PER_SEC);
+
+ if (unlikely(r->linklayer == TC_LINKLAYER_ATM)) {
+ do_div(len, 53);
+ len = len * 48;
+ }
+
+ if (len > r->overhead)
+ len -= r->overhead;
+ else
+ len = 0;
+
+ return len;
+}
+
+/* GSO packet is too big, segment it so that tbf can transmit
+ * each segment in time
+ */
+static int tbf_segment(struct sk_buff *skb, struct Qdisc *sch,
+ struct sk_buff **to_free)
+{
+ struct tbf_sched_data *q = qdisc_priv(sch);
+ struct sk_buff *segs, *nskb;
+ netdev_features_t features = netif_skb_features(skb);
+ unsigned int len = 0, prev_len = qdisc_pkt_len(skb);
+ int ret, nb;
+
+ segs = skb_gso_segment(skb, features & ~NETIF_F_GSO_MASK);
+
+ if (IS_ERR_OR_NULL(segs))
+ return qdisc_drop(skb, sch, to_free);
+
+ nb = 0;
+ while (segs) {
+ nskb = segs->next;
+ segs->next = NULL;
+ qdisc_skb_cb(segs)->pkt_len = segs->len;
+ len += segs->len;
+ ret = qdisc_enqueue(segs, q->qdisc, to_free);
+ if (ret != NET_XMIT_SUCCESS) {
+ if (net_xmit_drop_count(ret))
+ qdisc_qstats_drop(sch);
+ } else {
+ nb++;
+ }
+ segs = nskb;
+ }
+ sch->q.qlen += nb;
+ if (nb > 1)
+ qdisc_tree_reduce_backlog(sch, 1 - nb, prev_len - len);
+ consume_skb(skb);
+ return nb > 0 ? NET_XMIT_SUCCESS : NET_XMIT_DROP;
+}
+
+static int tbf_enqueue(struct sk_buff *skb, struct Qdisc *sch,
+ struct sk_buff **to_free)
+{
+ struct tbf_sched_data *q = qdisc_priv(sch);
+ int ret;
+
+ if (qdisc_pkt_len(skb) > q->max_size) {
+ if (skb_is_gso(skb) &&
+ skb_gso_validate_mac_len(skb, q->max_size))
+ return tbf_segment(skb, sch, to_free);
+ return qdisc_drop(skb, sch, to_free);
+ }
+ ret = qdisc_enqueue(skb, q->qdisc, to_free);
+ if (ret != NET_XMIT_SUCCESS) {
+ if (net_xmit_drop_count(ret))
+ qdisc_qstats_drop(sch);
+ return ret;
+ }
+
+ qdisc_qstats_backlog_inc(sch, skb);
+ sch->q.qlen++;
+ return NET_XMIT_SUCCESS;
+}
+
+static bool tbf_peak_present(const struct tbf_sched_data *q)
+{
+ return q->peak.rate_bytes_ps;
+}
+
+static struct sk_buff *tbf_dequeue(struct Qdisc *sch)
+{
+ struct tbf_sched_data *q = qdisc_priv(sch);
+ struct sk_buff *skb;
+
+ skb = q->qdisc->ops->peek(q->qdisc);
+
+ if (skb) {
+ s64 now;
+ s64 toks;
+ s64 ptoks = 0;
+ unsigned int len = qdisc_pkt_len(skb);
+
+ now = ktime_get_ns();
+ toks = min_t(s64, now - q->t_c, q->buffer);
+
+ if (tbf_peak_present(q)) {
+ ptoks = toks + q->ptokens;
+ if (ptoks > q->mtu)
+ ptoks = q->mtu;
+ ptoks -= (s64) psched_l2t_ns(&q->peak, len);
+ }
+ toks += q->tokens;
+ if (toks > q->buffer)
+ toks = q->buffer;
+ toks -= (s64) psched_l2t_ns(&q->rate, len);
+
+ if ((toks|ptoks) >= 0) {
+ skb = qdisc_dequeue_peeked(q->qdisc);
+ if (unlikely(!skb))
+ return NULL;
+
+ q->t_c = now;
+ q->tokens = toks;
+ q->ptokens = ptoks;
+ qdisc_qstats_backlog_dec(sch, skb);
+ sch->q.qlen--;
+ qdisc_bstats_update(sch, skb);
+ return skb;
+ }
+
+ qdisc_watchdog_schedule_ns(&q->watchdog,
+ now + max_t(long, -toks, -ptoks));
+
+ /* Maybe we have a shorter packet in the queue,
+ which can be sent now. It sounds cool,
+ but, however, this is wrong in principle.
+ We MUST NOT reorder packets under these circumstances.
+
+ Really, if we split the flow into independent
+ subflows, it would be a very good solution.
+ This is the main idea of all FQ algorithms
+ (cf. CSZ, HPFQ, HFSC)
+ */
+
+ qdisc_qstats_overlimit(sch);
+ }
+ return NULL;
+}
+
+static void tbf_reset(struct Qdisc *sch)
+{
+ struct tbf_sched_data *q = qdisc_priv(sch);
+
+ qdisc_reset(q->qdisc);
+ sch->qstats.backlog = 0;
+ sch->q.qlen = 0;
+ q->t_c = ktime_get_ns();
+ q->tokens = q->buffer;
+ q->ptokens = q->mtu;
+ qdisc_watchdog_cancel(&q->watchdog);
+}
+
+static const struct nla_policy tbf_policy[TCA_TBF_MAX + 1] = {
+ [TCA_TBF_PARMS] = { .len = sizeof(struct tc_tbf_qopt) },
+ [TCA_TBF_RTAB] = { .type = NLA_BINARY, .len = TC_RTAB_SIZE },
+ [TCA_TBF_PTAB] = { .type = NLA_BINARY, .len = TC_RTAB_SIZE },
+ [TCA_TBF_RATE64] = { .type = NLA_U64 },
+ [TCA_TBF_PRATE64] = { .type = NLA_U64 },
+ [TCA_TBF_BURST] = { .type = NLA_U32 },
+ [TCA_TBF_PBURST] = { .type = NLA_U32 },
+};
+
+static int tbf_change(struct Qdisc *sch, struct nlattr *opt,
+ struct netlink_ext_ack *extack)
+{
+ int err;
+ struct tbf_sched_data *q = qdisc_priv(sch);
+ struct nlattr *tb[TCA_TBF_MAX + 1];
+ struct tc_tbf_qopt *qopt;
+ struct Qdisc *child = NULL;
+ struct psched_ratecfg rate;
+ struct psched_ratecfg peak;
+ u64 max_size;
+ s64 buffer, mtu;
+ u64 rate64 = 0, prate64 = 0;
+
+ err = nla_parse_nested(tb, TCA_TBF_MAX, opt, tbf_policy, NULL);
+ if (err < 0)
+ return err;
+
+ err = -EINVAL;
+ if (tb[TCA_TBF_PARMS] == NULL)
+ goto done;
+
+ qopt = nla_data(tb[TCA_TBF_PARMS]);
+ if (qopt->rate.linklayer == TC_LINKLAYER_UNAWARE)
+ qdisc_put_rtab(qdisc_get_rtab(&qopt->rate,
+ tb[TCA_TBF_RTAB],
+ NULL));
+
+ if (qopt->peakrate.linklayer == TC_LINKLAYER_UNAWARE)
+ qdisc_put_rtab(qdisc_get_rtab(&qopt->peakrate,
+ tb[TCA_TBF_PTAB],
+ NULL));
+
+ buffer = min_t(u64, PSCHED_TICKS2NS(qopt->buffer), ~0U);
+ mtu = min_t(u64, PSCHED_TICKS2NS(qopt->mtu), ~0U);
+
+ if (tb[TCA_TBF_RATE64])
+ rate64 = nla_get_u64(tb[TCA_TBF_RATE64]);
+ psched_ratecfg_precompute(&rate, &qopt->rate, rate64);
+
+ if (tb[TCA_TBF_BURST]) {
+ max_size = nla_get_u32(tb[TCA_TBF_BURST]);
+ buffer = psched_l2t_ns(&rate, max_size);
+ } else {
+ max_size = min_t(u64, psched_ns_t2l(&rate, buffer), ~0U);
+ }
+
+ if (qopt->peakrate.rate) {
+ if (tb[TCA_TBF_PRATE64])
+ prate64 = nla_get_u64(tb[TCA_TBF_PRATE64]);
+ psched_ratecfg_precompute(&peak, &qopt->peakrate, prate64);
+ if (peak.rate_bytes_ps <= rate.rate_bytes_ps) {
+ pr_warn_ratelimited("sch_tbf: peakrate %llu is lower than or equals to rate %llu !\n",
+ peak.rate_bytes_ps, rate.rate_bytes_ps);
+ err = -EINVAL;
+ goto done;
+ }
+
+ if (tb[TCA_TBF_PBURST]) {
+ u32 pburst = nla_get_u32(tb[TCA_TBF_PBURST]);
+ max_size = min_t(u32, max_size, pburst);
+ mtu = psched_l2t_ns(&peak, pburst);
+ } else {
+ max_size = min_t(u64, max_size, psched_ns_t2l(&peak, mtu));
+ }
+ } else {
+ memset(&peak, 0, sizeof(peak));
+ }
+
+ if (max_size < psched_mtu(qdisc_dev(sch)))
+ pr_warn_ratelimited("sch_tbf: burst %llu is lower than device %s mtu (%u) !\n",
+ max_size, qdisc_dev(sch)->name,
+ psched_mtu(qdisc_dev(sch)));
+
+ if (!max_size) {
+ err = -EINVAL;
+ goto done;
+ }
+
+ if (q->qdisc != &noop_qdisc) {
+ err = fifo_set_limit(q->qdisc, qopt->limit);
+ if (err)
+ goto done;
+ } else if (qopt->limit > 0) {
+ child = fifo_create_dflt(sch, &bfifo_qdisc_ops, qopt->limit,
+ extack);
+ if (IS_ERR(child)) {
+ err = PTR_ERR(child);
+ goto done;
+ }
+
+ /* child is fifo, no need to check for noop_qdisc */
+ qdisc_hash_add(child, true);
+ }
+
+ sch_tree_lock(sch);
+ if (child) {
+ qdisc_tree_reduce_backlog(q->qdisc, q->qdisc->q.qlen,
+ q->qdisc->qstats.backlog);
+ qdisc_put(q->qdisc);
+ q->qdisc = child;
+ }
+ q->limit = qopt->limit;
+ if (tb[TCA_TBF_PBURST])
+ q->mtu = mtu;
+ else
+ q->mtu = PSCHED_TICKS2NS(qopt->mtu);
+ q->max_size = max_size;
+ if (tb[TCA_TBF_BURST])
+ q->buffer = buffer;
+ else
+ q->buffer = PSCHED_TICKS2NS(qopt->buffer);
+ q->tokens = q->buffer;
+ q->ptokens = q->mtu;
+
+ memcpy(&q->rate, &rate, sizeof(struct psched_ratecfg));
+ memcpy(&q->peak, &peak, sizeof(struct psched_ratecfg));
+
+ sch_tree_unlock(sch);
+ err = 0;
+done:
+ return err;
+}
+
+static int tbf_init(struct Qdisc *sch, struct nlattr *opt,
+ struct netlink_ext_ack *extack)
+{
+ struct tbf_sched_data *q = qdisc_priv(sch);
+
+ qdisc_watchdog_init(&q->watchdog, sch);
+ q->qdisc = &noop_qdisc;
+
+ if (!opt)
+ return -EINVAL;
+
+ q->t_c = ktime_get_ns();
+
+ return tbf_change(sch, opt, extack);
+}
+
+static void tbf_destroy(struct Qdisc *sch)
+{
+ struct tbf_sched_data *q = qdisc_priv(sch);
+
+ qdisc_watchdog_cancel(&q->watchdog);
+ qdisc_put(q->qdisc);
+}
+
+static int tbf_dump(struct Qdisc *sch, struct sk_buff *skb)
+{
+ struct tbf_sched_data *q = qdisc_priv(sch);
+ struct nlattr *nest;
+ struct tc_tbf_qopt opt;
+
+ sch->qstats.backlog = q->qdisc->qstats.backlog;
+ nest = nla_nest_start(skb, TCA_OPTIONS);
+ if (nest == NULL)
+ goto nla_put_failure;
+
+ opt.limit = q->limit;
+ psched_ratecfg_getrate(&opt.rate, &q->rate);
+ if (tbf_peak_present(q))
+ psched_ratecfg_getrate(&opt.peakrate, &q->peak);
+ else
+ memset(&opt.peakrate, 0, sizeof(opt.peakrate));
+ opt.mtu = PSCHED_NS2TICKS(q->mtu);
+ opt.buffer = PSCHED_NS2TICKS(q->buffer);
+ if (nla_put(skb, TCA_TBF_PARMS, sizeof(opt), &opt))
+ goto nla_put_failure;
+ if (q->rate.rate_bytes_ps >= (1ULL << 32) &&
+ nla_put_u64_64bit(skb, TCA_TBF_RATE64, q->rate.rate_bytes_ps,
+ TCA_TBF_PAD))
+ goto nla_put_failure;
+ if (tbf_peak_present(q) &&
+ q->peak.rate_bytes_ps >= (1ULL << 32) &&
+ nla_put_u64_64bit(skb, TCA_TBF_PRATE64, q->peak.rate_bytes_ps,
+ TCA_TBF_PAD))
+ goto nla_put_failure;
+
+ return nla_nest_end(skb, nest);
+
+nla_put_failure:
+ nla_nest_cancel(skb, nest);
+ return -1;
+}
+
+static int tbf_dump_class(struct Qdisc *sch, unsigned long cl,
+ struct sk_buff *skb, struct tcmsg *tcm)
+{
+ struct tbf_sched_data *q = qdisc_priv(sch);
+
+ tcm->tcm_handle |= TC_H_MIN(1);
+ tcm->tcm_info = q->qdisc->handle;
+
+ return 0;
+}
+
+static int tbf_graft(struct Qdisc *sch, unsigned long arg, struct Qdisc *new,
+ struct Qdisc **old, struct netlink_ext_ack *extack)
+{
+ struct tbf_sched_data *q = qdisc_priv(sch);
+
+ if (new == NULL)
+ new = &noop_qdisc;
+
+ *old = qdisc_replace(sch, new, &q->qdisc);
+ return 0;
+}
+
+static struct Qdisc *tbf_leaf(struct Qdisc *sch, unsigned long arg)
+{
+ struct tbf_sched_data *q = qdisc_priv(sch);
+ return q->qdisc;
+}
+
+static unsigned long tbf_find(struct Qdisc *sch, u32 classid)
+{
+ return 1;
+}
+
+static void tbf_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 const struct Qdisc_class_ops tbf_class_ops = {
+ .graft = tbf_graft,
+ .leaf = tbf_leaf,
+ .find = tbf_find,
+ .walk = tbf_walk,
+ .dump = tbf_dump_class,
+};
+
+static struct Qdisc_ops tbf_qdisc_ops __read_mostly = {
+ .next = NULL,
+ .cl_ops = &tbf_class_ops,
+ .id = "tbf",
+ .priv_size = sizeof(struct tbf_sched_data),
+ .enqueue = tbf_enqueue,
+ .dequeue = tbf_dequeue,
+ .peek = qdisc_peek_dequeued,
+ .init = tbf_init,
+ .reset = tbf_reset,
+ .destroy = tbf_destroy,
+ .change = tbf_change,
+ .dump = tbf_dump,
+ .owner = THIS_MODULE,
+};
+
+static int __init tbf_module_init(void)
+{
+ return register_qdisc(&tbf_qdisc_ops);
+}
+
+static void __exit tbf_module_exit(void)
+{
+ unregister_qdisc(&tbf_qdisc_ops);
+}
+module_init(tbf_module_init)
+module_exit(tbf_module_exit)
+MODULE_LICENSE("GPL");
generated by cgit v1.2.3 (git 2.39.1) at 2024-11-24 10:40:25 +0000