diff options
Diffstat (limited to 'net/sched')
| -rw-r--r-- | net/sched/Kconfig | 26 | ||||
| -rw-r--r-- | net/sched/Makefile | 1 | ||||
| -rw-r--r-- | net/sched/cls_cgroup.c | 10 | ||||
| -rw-r--r-- | net/sched/sch_choke.c | 3 | ||||
| -rw-r--r-- | net/sched/sch_netem.c | 11 | ||||
| -rw-r--r-- | net/sched/sch_plug.c | 233 | ||||
| -rw-r--r-- | net/sched/sch_sfb.c | 3 | ||||
| -rw-r--r-- | net/sched/sch_sfq.c | 11 |
8 files changed, 277 insertions, 21 deletions
diff --git a/net/sched/Kconfig b/net/sched/Kconfig index 2590e91b328..75b58f81d53 100644 --- a/net/sched/Kconfig +++ b/net/sched/Kconfig @@ -260,6 +260,32 @@ config NET_SCH_INGRESS To compile this code as a module, choose M here: the module will be called sch_ingress. +config NET_SCH_PLUG + tristate "Plug network traffic until release (PLUG)" + ---help--- + + This queuing discipline allows userspace to plug/unplug a network + output queue, using the netlink interface. When it receives an + enqueue command it inserts a plug into the outbound queue that + causes following packets to enqueue until a dequeue command arrives + over netlink, causing the plug to be removed and resuming the normal + packet flow. + + This module also provides a generic "network output buffering" + functionality (aka output commit), wherein upon arrival of a dequeue + command, only packets up to the first plug are released for delivery. + The Remus HA project uses this module to enable speculative execution + of virtual machines by allowing the generated network output to be rolled + back if needed. + + For more information, please refer to http://wiki.xensource.com/xenwiki/Remus + + Say Y here if you are using this kernel for Xen dom0 and + want to protect Xen guests with Remus. + + To compile this code as a module, choose M here: the + module will be called sch_plug. + comment "Classification" config NET_CLS diff --git a/net/sched/Makefile b/net/sched/Makefile index dc5889c0a15..8cdf4e2b51d 100644 --- a/net/sched/Makefile +++ b/net/sched/Makefile @@ -33,6 +33,7 @@ obj-$(CONFIG_NET_SCH_MULTIQ) += sch_multiq.o obj-$(CONFIG_NET_SCH_ATM) += sch_atm.o obj-$(CONFIG_NET_SCH_NETEM) += sch_netem.o obj-$(CONFIG_NET_SCH_DRR) += sch_drr.o +obj-$(CONFIG_NET_SCH_PLUG) += sch_plug.o obj-$(CONFIG_NET_SCH_MQPRIO) += sch_mqprio.o obj-$(CONFIG_NET_SCH_CHOKE) += sch_choke.o obj-$(CONFIG_NET_SCH_QFQ) += sch_qfq.o diff --git a/net/sched/cls_cgroup.c b/net/sched/cls_cgroup.c index f84fdc3a7f2..1afaa284fcd 100644 --- a/net/sched/cls_cgroup.c +++ b/net/sched/cls_cgroup.c @@ -22,9 +22,8 @@ #include <net/sock.h> #include <net/cls_cgroup.h> -static struct cgroup_subsys_state *cgrp_create(struct cgroup_subsys *ss, - struct cgroup *cgrp); -static void cgrp_destroy(struct cgroup_subsys *ss, struct cgroup *cgrp); +static struct cgroup_subsys_state *cgrp_create(struct cgroup *cgrp); +static void cgrp_destroy(struct cgroup *cgrp); static int cgrp_populate(struct cgroup_subsys *ss, struct cgroup *cgrp); struct cgroup_subsys net_cls_subsys = { @@ -51,8 +50,7 @@ static inline struct cgroup_cls_state *task_cls_state(struct task_struct *p) struct cgroup_cls_state, css); } -static struct cgroup_subsys_state *cgrp_create(struct cgroup_subsys *ss, - struct cgroup *cgrp) +static struct cgroup_subsys_state *cgrp_create(struct cgroup *cgrp) { struct cgroup_cls_state *cs; @@ -66,7 +64,7 @@ static struct cgroup_subsys_state *cgrp_create(struct cgroup_subsys *ss, return &cs->css; } -static void cgrp_destroy(struct cgroup_subsys *ss, struct cgroup *cgrp) +static void cgrp_destroy(struct cgroup *cgrp) { kfree(cgrp_cls_state(cgrp)); } diff --git a/net/sched/sch_choke.c b/net/sched/sch_choke.c index e465064d39a..7e267d7b9c7 100644 --- a/net/sched/sch_choke.c +++ b/net/sched/sch_choke.c @@ -148,8 +148,7 @@ struct choke_skb_cb { static inline struct choke_skb_cb *choke_skb_cb(const struct sk_buff *skb) { - BUILD_BUG_ON(sizeof(skb->cb) < - sizeof(struct qdisc_skb_cb) + sizeof(struct choke_skb_cb)); + qdisc_cb_private_validate(skb, sizeof(struct choke_skb_cb)); return (struct choke_skb_cb *)qdisc_skb_cb(skb)->data; } diff --git a/net/sched/sch_netem.c b/net/sched/sch_netem.c index e7e1d0b57b3..5da548fa7ae 100644 --- a/net/sched/sch_netem.c +++ b/net/sched/sch_netem.c @@ -130,8 +130,7 @@ struct netem_skb_cb { static inline struct netem_skb_cb *netem_skb_cb(struct sk_buff *skb) { - BUILD_BUG_ON(sizeof(skb->cb) < - sizeof(struct qdisc_skb_cb) + sizeof(struct netem_skb_cb)); + qdisc_cb_private_validate(skb, sizeof(struct netem_skb_cb)); return (struct netem_skb_cb *)qdisc_skb_cb(skb)->data; } @@ -419,7 +418,7 @@ static int netem_enqueue(struct sk_buff *skb, struct Qdisc *sch) cb = netem_skb_cb(skb); if (q->gap == 0 || /* not doing reordering */ - q->counter < q->gap || /* inside last reordering gap */ + q->counter < q->gap - 1 || /* inside last reordering gap */ q->reorder < get_crandom(&q->reorder_cor)) { psched_time_t now; psched_tdiff_t delay; @@ -502,9 +501,8 @@ tfifo_dequeue: /* if more time remaining? */ if (cb->time_to_send <= psched_get_time()) { - skb = qdisc_dequeue_tail(sch); - if (unlikely(!skb)) - goto qdisc_dequeue; + __skb_unlink(skb, &sch->q); + sch->qstats.backlog -= qdisc_pkt_len(skb); #ifdef CONFIG_NET_CLS_ACT /* @@ -540,7 +538,6 @@ deliver: qdisc_watchdog_schedule(&q->watchdog, cb->time_to_send); } -qdisc_dequeue: if (q->qdisc) { skb = q->qdisc->ops->dequeue(q->qdisc); if (skb) diff --git a/net/sched/sch_plug.c b/net/sched/sch_plug.c new file mode 100644 index 00000000000..89f8fcf73f1 --- /dev/null +++ b/net/sched/sch_plug.c @@ -0,0 +1,233 @@ +/* + * sch_plug.c Queue traffic until an explicit release command + * + * 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. + * + * There are two ways to use this qdisc: + * 1. A simple "instantaneous" plug/unplug operation, by issuing an alternating + * sequence of TCQ_PLUG_BUFFER & TCQ_PLUG_RELEASE_INDEFINITE commands. + * + * 2. For network output buffering (a.k.a output commit) functionality. + * Output commit property is commonly used by applications using checkpoint + * based fault-tolerance to ensure that the checkpoint from which a system + * is being restored is consistent w.r.t outside world. + * + * Consider for e.g. Remus - a Virtual Machine checkpointing system, + * wherein a VM is checkpointed, say every 50ms. The checkpoint is replicated + * asynchronously to the backup host, while the VM continues executing the + * next epoch speculatively. + * + * The following is a typical sequence of output buffer operations: + * 1.At epoch i, start_buffer(i) + * 2. At end of epoch i (i.e. after 50ms): + * 2.1 Stop VM and take checkpoint(i). + * 2.2 start_buffer(i+1) and Resume VM + * 3. While speculatively executing epoch(i+1), asynchronously replicate + * checkpoint(i) to backup host. + * 4. When checkpoint_ack(i) is received from backup, release_buffer(i) + * Thus, this Qdisc would receive the following sequence of commands: + * TCQ_PLUG_BUFFER (epoch i) + * .. TCQ_PLUG_BUFFER (epoch i+1) + * ....TCQ_PLUG_RELEASE_ONE (epoch i) + * ......TCQ_PLUG_BUFFER (epoch i+2) + * ........ + */ + +#include <linux/module.h> +#include <linux/types.h> +#include <linux/kernel.h> +#include <linux/errno.h> +#include <linux/netdevice.h> +#include <linux/skbuff.h> +#include <net/pkt_sched.h> + +/* + * State of the queue, when used for network output buffering: + * + * plug(i+1) plug(i) head + * ------------------+--------------------+----------------> + * | | + * | | + * pkts_current_epoch| pkts_last_epoch |pkts_to_release + * ----------------->|<--------+--------->|+---------------> + * v v + * + */ + +struct plug_sched_data { + /* If true, the dequeue function releases all packets + * from head to end of the queue. The queue turns into + * a pass-through queue for newly arriving packets. + */ + bool unplug_indefinite; + + /* Queue Limit in bytes */ + u32 limit; + + /* Number of packets (output) from the current speculatively + * executing epoch. + */ + u32 pkts_current_epoch; + + /* Number of packets corresponding to the recently finished + * epoch. These will be released when we receive a + * TCQ_PLUG_RELEASE_ONE command. This command is typically + * issued after committing a checkpoint at the target. + */ + u32 pkts_last_epoch; + + /* + * Number of packets from the head of the queue, that can + * be released (committed checkpoint). + */ + u32 pkts_to_release; +}; + +static int plug_enqueue(struct sk_buff *skb, struct Qdisc *sch) +{ + struct plug_sched_data *q = qdisc_priv(sch); + + if (likely(sch->qstats.backlog + skb->len <= q->limit)) { + if (!q->unplug_indefinite) + q->pkts_current_epoch++; + return qdisc_enqueue_tail(skb, sch); + } + + return qdisc_reshape_fail(skb, sch); +} + +static struct sk_buff *plug_dequeue(struct Qdisc *sch) +{ + struct plug_sched_data *q = qdisc_priv(sch); + + if (qdisc_is_throttled(sch)) + return NULL; + + if (!q->unplug_indefinite) { + if (!q->pkts_to_release) { + /* No more packets to dequeue. Block the queue + * and wait for the next release command. + */ + qdisc_throttled(sch); + return NULL; + } + q->pkts_to_release--; + } + + return qdisc_dequeue_head(sch); +} + +static int plug_init(struct Qdisc *sch, struct nlattr *opt) +{ + struct plug_sched_data *q = qdisc_priv(sch); + + q->pkts_current_epoch = 0; + q->pkts_last_epoch = 0; + q->pkts_to_release = 0; + q->unplug_indefinite = false; + + if (opt == NULL) { + /* We will set a default limit of 100 pkts (~150kB) + * in case tx_queue_len is not available. The + * default value is completely arbitrary. + */ + u32 pkt_limit = qdisc_dev(sch)->tx_queue_len ? : 100; + q->limit = pkt_limit * psched_mtu(qdisc_dev(sch)); + } else { + struct tc_plug_qopt *ctl = nla_data(opt); + + if (nla_len(opt) < sizeof(*ctl)) + return -EINVAL; + + q->limit = ctl->limit; + } + + qdisc_throttled(sch); + return 0; +} + +/* Receives 4 types of messages: + * TCQ_PLUG_BUFFER: Inset a plug into the queue and + * buffer any incoming packets + * TCQ_PLUG_RELEASE_ONE: Dequeue packets from queue head + * to beginning of the next plug. + * TCQ_PLUG_RELEASE_INDEFINITE: Dequeue all packets from queue. + * Stop buffering packets until the next TCQ_PLUG_BUFFER + * command is received (just act as a pass-thru queue). + * TCQ_PLUG_LIMIT: Increase/decrease queue size + */ +static int plug_change(struct Qdisc *sch, struct nlattr *opt) +{ + struct plug_sched_data *q = qdisc_priv(sch); + struct tc_plug_qopt *msg; + + if (opt == NULL) + return -EINVAL; + + msg = nla_data(opt); + if (nla_len(opt) < sizeof(*msg)) + return -EINVAL; + + switch (msg->action) { + case TCQ_PLUG_BUFFER: + /* Save size of the current buffer */ + q->pkts_last_epoch = q->pkts_current_epoch; + q->pkts_current_epoch = 0; + if (q->unplug_indefinite) + qdisc_throttled(sch); + q->unplug_indefinite = false; + break; + case TCQ_PLUG_RELEASE_ONE: + /* Add packets from the last complete buffer to the + * packets to be released set. + */ + q->pkts_to_release += q->pkts_last_epoch; + q->pkts_last_epoch = 0; + qdisc_unthrottled(sch); + netif_schedule_queue(sch->dev_queue); + break; + case TCQ_PLUG_RELEASE_INDEFINITE: + q->unplug_indefinite = true; + q->pkts_to_release = 0; + q->pkts_last_epoch = 0; + q->pkts_current_epoch = 0; + qdisc_unthrottled(sch); + netif_schedule_queue(sch->dev_queue); + break; + case TCQ_PLUG_LIMIT: + /* Limit is supplied in bytes */ + q->limit = msg->limit; + break; + default: + return -EINVAL; + } + + return 0; +} + +static struct Qdisc_ops plug_qdisc_ops __read_mostly = { + .id = "plug", + .priv_size = sizeof(struct plug_sched_data), + .enqueue = plug_enqueue, + .dequeue = plug_dequeue, + .peek = qdisc_peek_head, + .init = plug_init, + .change = plug_change, + .owner = THIS_MODULE, +}; + +static int __init plug_module_init(void) +{ + return register_qdisc(&plug_qdisc_ops); +} + +static void __exit plug_module_exit(void) +{ + unregister_qdisc(&plug_qdisc_ops); +} +module_init(plug_module_init) +module_exit(plug_module_exit) +MODULE_LICENSE("GPL"); diff --git a/net/sched/sch_sfb.c b/net/sched/sch_sfb.c index 96e42cae4c7..d7eea99333e 100644 --- a/net/sched/sch_sfb.c +++ b/net/sched/sch_sfb.c @@ -94,8 +94,7 @@ struct sfb_skb_cb { 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)); + qdisc_cb_private_validate(skb, sizeof(struct sfb_skb_cb)); return (struct sfb_skb_cb *)qdisc_skb_cb(skb)->data; } diff --git a/net/sched/sch_sfq.c b/net/sched/sch_sfq.c index 67494aef9ac..02a21abea65 100644 --- a/net/sched/sch_sfq.c +++ b/net/sched/sch_sfq.c @@ -166,9 +166,8 @@ struct sfq_skb_cb { static inline struct sfq_skb_cb *sfq_skb_cb(const struct sk_buff *skb) { - BUILD_BUG_ON(sizeof(skb->cb) < - sizeof(struct qdisc_skb_cb) + sizeof(struct sfq_skb_cb)); - return (struct sfq_skb_cb *)qdisc_skb_cb(skb)->data; + qdisc_cb_private_validate(skb, sizeof(struct sfq_skb_cb)); + return (struct sfq_skb_cb *)qdisc_skb_cb(skb)->data; } static unsigned int sfq_hash(const struct sfq_sched_data *q, @@ -470,11 +469,15 @@ enqueue: if (slot->qlen == 1) { /* The flow is new */ if (q->tail == NULL) { /* It is the first flow */ slot->next = x; - q->tail = slot; } else { slot->next = q->tail->next; q->tail->next = x; } + /* We put this flow at the end of our flow list. + * This might sound unfair for a new flow to wait after old ones, + * but we could endup servicing new flows only, and freeze old ones. + */ + q->tail = slot; /* We could use a bigger initial quantum for new flows */ slot->allot = q->scaled_quantum; } |