[next-queue,v4,3/4] net/sched: Introduce Credit Based Shaper (CBS) qdisc

Message ID	20171004002831.18371-4-vinicius.gomes@intel.com
State	Changes Requested
Headers	show Return-Path: <intel-wired-lan-bounces@osuosl.org> From: Vinicius Costa Gomes <vinicius.gomes@intel.com> To: netdev@vger.kernel.org, intel-wired-lan@lists.osuosl.org Date: Tue, 3 Oct 2017 17:28:30 -0700 Message-Id: <20171004002831.18371-4-vinicius.gomes@intel.com> In-Reply-To: <20171004002831.18371-1-vinicius.gomes@intel.com> References: <20171004002831.18371-1-vinicius.gomes@intel.com> Cc: rodney.cummings@ni.com, andre.guedes@intel.com, jiri@resnulli.us, ivan.briano@intel.com, richardcochran@gmail.com, henrik@austad.us, jhs@mojatatu.com, levipearson@gmail.com, boon.leong.ong@intel.com, xiyou.wangcong@gmail.com, jesus.sanchez-palencia@intel.com Subject: [Intel-wired-lan] [next-queue PATCH v4 3/4] net/sched: Introduce Credit Based Shaper (CBS) qdisc Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: intel-wired-lan-bounces@osuosl.org Sender: "Intel-wired-lan" <intel-wired-lan-bounces@osuosl.org>
Series	TSN: Add qdisc based config interface for CBS \| expand [next-queue,v4,0/4] TSN: Add qdisc based config interface for CBS [next-queue,v4,1/4] mqprio: Implement select_queue class_ops [next-queue,v4,2/4] net/sched: Fix accessing invalid dev_queue [next-queue,v4,3/4] net/sched: Introduce Credit Based Shaper (CBS) qdisc [next-queue,v4,4/4] igb: Add support for CBS offload

diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h index e1d6ef130611..b8798adc214f 100644 --- a/include/linux/netdevice.h +++ b/include/linux/netdevice.h @@ -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 diff --git a/include/net/pkt_sched.h b/include/net/pkt_sched.h index 259bc191ba59..7c597b050b36 100644 --- a/include/net/pkt_sched.h +++ b/include/net/pkt_sched.h @@ -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 diff --git a/include/uapi/linux/pkt_sched.h b/include/uapi/linux/pkt_sched.h index 099bf5528fed..27c849c053cf 100644 --- a/include/uapi/linux/pkt_sched.h +++ b/include/uapi/linux/pkt_sched.h @@ -871,4 +871,21 @@ struct tc_pie_xstats { __u32 maxq; /* maximum queue size */ __u32 ecn_mark; /* packets marked with ecn*/ }; + +/* CBS */ +struct tc_cbs_qopt { + __s32 hicredit; + __s32 locredit; + __s32 idleslope; + __s32 sendslope; +}; + +enum { + TCA_CBS_UNSPEC, + TCA_CBS_PARMS, + __TCA_CBS_MAX, +}; + +#define TCA_CBS_MAX (__TCA_CBS_MAX - 1) + #endif diff --git a/net/sched/Kconfig b/net/sched/Kconfig index e70ed26485a2..c03d86a7775e 100644 --- a/net/sched/Kconfig +++ b/net/sched/Kconfig @@ -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--- diff --git a/net/sched/Makefile b/net/sched/Makefile index 7b915d226de7..80c8f92d162d 100644 --- a/net/sched/Makefile +++ b/net/sched/Makefile @@ -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 diff --git a/net/sched/sch_cbs.c b/net/sched/sch_cbs.c new file mode 100644 index 000000000000..3e0fb0b92160 --- /dev/null +++ b/net/sched/sch_cbs.c @@ -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");

[next-queue,v4,3/4] net/sched: Introduce Credit Based Shaper (CBS) qdisc

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