@@ -775,6 +775,7 @@ enum tc_setup_type {
TC_SETUP_CLSFLOWER,
TC_SETUP_CLSMATCHALL,
TC_SETUP_CLSBPF,
+ TC_SETUP_CBS,
};
/* These structures hold the attributes of xdp state that are being passed
@@ -146,4 +146,13 @@ static inline bool is_classid_clsact_egress(u32 classid)
TC_H_MIN(classid) == TC_H_MIN(TC_H_MIN_EGRESS);
}
+struct tc_cbs_qopt_offload {
+ u8 enable;
+ s32 queue;
+ s32 hicredit;
+ s32 locredit;
+ s32 idleslope;
+ s32 sendslope;
+};
+
#endif
@@ -172,6 +172,17 @@ config NET_SCH_TBF
To compile this code as a module, choose M here: the
module will be called sch_tbf.
+config NET_SCH_CBS
+ tristate "Credit Based Shaper (CBS)"
+ ---help---
+ Say Y here if you want to use the Credit Based Shaper (CBS) packet
+ scheduling algorithm.
+
+ See the top of <file:net/sched/sch_cbs.c> for more details.
+
+ To compile this code as a module, choose M here: the
+ module will be called sch_cbs.
+
config NET_SCH_GRED
tristate "Generic Random Early Detection (GRED)"
---help---
@@ -52,6 +52,7 @@ obj-$(CONFIG_NET_SCH_FQ_CODEL) += sch_fq_codel.o
obj-$(CONFIG_NET_SCH_FQ) += sch_fq.o
obj-$(CONFIG_NET_SCH_HHF) += sch_hhf.o
obj-$(CONFIG_NET_SCH_PIE) += sch_pie.o
+obj-$(CONFIG_NET_SCH_CBS) += sch_cbs.o
obj-$(CONFIG_NET_CLS_U32) += cls_u32.o
obj-$(CONFIG_NET_CLS_ROUTE4) += cls_route.o
new file mode 100644
@@ -0,0 +1,225 @@
+/*
+ * net/sched/sch_cbs.c Credit Based Shaper
+ *
+ * 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: Vinicius Costa Gomes <vinicius.gomes@intel.com>
+ *
+ */
+
+/* Credit Based Shaper (CBS)
+ =========================
+
+ This is a simple rate-limiting shaper aimed at TSN applications on
+ systems with known traffic workloads.
+
+ Its algorithm is defined by the IEEE 802.1Q-2014 Specification,
+ Section 8.6.8.2, and explained in more detail in the Annex L of the
+ same specification.
+
+ There are four tunables to be considered:
+
+ 'idleslope': Idleslope is the rate of credits that is
+ accumulated (in kilobits per second) when there is at least
+ one packet waiting for transmission. Packets are transmitted
+ when the current value of credits is equal or greater than
+ zero. When there is no packet to be transmitted the amount of
+ credits is set to zero. This is the main tunable of the CBS
+ algorithm.
+
+ 'sendslope':
+ Sendslope is the rate of credits that is depleted (it should be a
+ negative number of kilobits per second) when a transmission is
+ ocurring. It can be calculated as follows, (IEEE 802.1Q-2014 Section
+ 8.6.8.2 item g):
+
+ sendslope = idleslope - port_transmit_rate
+
+ 'hicredit': Hicredit defines the maximum amount of credits (in
+ bytes) that can be accumulated. Hicredit depends on the
+ characteristics of interfering traffic,
+ 'max_interference_size' is the maximum size of any burst of
+ traffic that can delay the transmission of a frame that is
+ available for transmission for this traffic class, (IEEE
+ 802.1Q-2014 Annex L, Equation L-3):
+
+ hicredit = max_interference_size * (idleslope / port_transmit_rate)
+
+ 'locredit': Locredit is the minimum amount of credits that can
+ be reached. It is a function of the traffic flowing through
+ this qdisc (IEEE 802.1Q-2014 Annex L, Equation L-2):
+
+ locredit = max_frame_size * (sendslope / port_transmit_rate)
+*/
+
+#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>
+
+struct cbs_sched_data {
+ s32 queue;
+ s32 locredit;
+ s32 hicredit;
+ s32 sendslope;
+ s32 idleslope;
+};
+
+static int cbs_enqueue(struct sk_buff *skb, struct Qdisc *sch,
+ struct sk_buff **to_free)
+{
+ return qdisc_enqueue_tail(skb, sch);
+}
+
+static const struct nla_policy cbs_policy[TCA_CBS_MAX + 1] = {
+ [TCA_CBS_PARMS] = { .len = sizeof(struct tc_cbs_qopt) },
+};
+
+static int cbs_change(struct Qdisc *sch, struct nlattr *opt)
+{
+ struct cbs_sched_data *q = qdisc_priv(sch);
+ struct tc_cbs_qopt_offload cbs = { };
+ struct nlattr *tb[TCA_CBS_MAX + 1];
+ const struct net_device_ops *ops;
+ struct tc_cbs_qopt *qopt;
+ struct net_device *dev;
+ int err;
+
+ err = nla_parse_nested(tb, TCA_CBS_MAX, opt, cbs_policy, NULL);
+ if (err < 0)
+ return err;
+
+ err = -EINVAL;
+ if (!tb[TCA_CBS_PARMS])
+ goto done;
+
+ qopt = nla_data(tb[TCA_CBS_PARMS]);
+
+ dev = qdisc_dev(sch);
+ ops = dev->netdev_ops;
+
+ cbs.queue = q->queue;
+ cbs.enable = 1;
+ cbs.hicredit = qopt->hicredit;
+ cbs.locredit = qopt->locredit;
+ cbs.idleslope = qopt->idleslope;
+ cbs.sendslope = qopt->sendslope;
+
+ err = -EOPNOTSUPP;
+ if (!ops->ndo_setup_tc)
+ goto done;
+
+ err = ops->ndo_setup_tc(dev, TC_SETUP_CBS, &cbs);
+ if (err < 0)
+ goto done;
+
+ q->hicredit = cbs.hicredit;
+ q->locredit = cbs.locredit;
+ q->idleslope = cbs.idleslope;
+ q->sendslope = cbs.sendslope;
+
+done:
+ return err;
+}
+
+static int cbs_init(struct Qdisc *sch, struct nlattr *opt)
+{
+ struct cbs_sched_data *q = qdisc_priv(sch);
+ struct net_device *dev = qdisc_dev(sch);
+
+ if (!opt)
+ return -EINVAL;
+
+ q->queue = sch->dev_queue - netdev_get_tx_queue(dev, 0);
+
+ return cbs_change(sch, opt);
+}
+
+static void cbs_destroy(struct Qdisc *sch)
+{
+ struct cbs_sched_data *q = qdisc_priv(sch);
+ struct tc_cbs_qopt_offload cbs = { };
+ const struct net_device_ops *ops;
+ struct net_device *dev;
+ int err;
+
+ q->hicredit = 0;
+ q->locredit = 0;
+ q->idleslope = 0;
+ q->sendslope = 0;
+
+ dev = qdisc_dev(sch);
+ ops = dev->netdev_ops;
+
+ if (!ops->ndo_setup_tc)
+ return;
+
+ cbs.queue = q->queue;
+ cbs.enable = 0;
+
+ err = ops->ndo_setup_tc(dev, TC_SETUP_CBS, &cbs);
+ if (err < 0)
+ pr_warn("Couldn't reset queue %d to default values\n",
+ cbs.queue);
+}
+
+static int cbs_dump(struct Qdisc *sch, struct sk_buff *skb)
+{
+ struct cbs_sched_data *q = qdisc_priv(sch);
+ struct nlattr *nest;
+ struct tc_cbs_qopt opt;
+
+ nest = nla_nest_start(skb, TCA_OPTIONS);
+ if (!nest)
+ goto nla_put_failure;
+
+ opt.hicredit = q->hicredit;
+ opt.locredit = q->locredit;
+ opt.sendslope = q->sendslope;
+ opt.idleslope = q->idleslope;
+
+ if (nla_put(skb, TCA_CBS_PARMS, sizeof(opt), &opt))
+ goto nla_put_failure;
+
+ return nla_nest_end(skb, nest);
+
+nla_put_failure:
+ nla_nest_cancel(skb, nest);
+ return -1;
+}
+
+static struct Qdisc_ops cbs_qdisc_ops __read_mostly = {
+ .next = NULL,
+ .id = "cbs",
+ .priv_size = sizeof(struct cbs_sched_data),
+ .enqueue = cbs_enqueue,
+ .dequeue = qdisc_dequeue_head,
+ .peek = qdisc_peek_dequeued,
+ .init = cbs_init,
+ .reset = qdisc_reset_queue,
+ .destroy = cbs_destroy,
+ .change = cbs_change,
+ .dump = cbs_dump,
+ .owner = THIS_MODULE,
+};
+
+static int __init cbs_module_init(void)
+{
+ return register_qdisc(&cbs_qdisc_ops);
+}
+
+static void __exit cbs_module_exit(void)
+{
+ unregister_qdisc(&cbs_qdisc_ops);
+}
+module_init(cbs_module_init)
+module_exit(cbs_module_exit)
+MODULE_LICENSE("GPL");