linux/net/sched/sch_drr.c
Florian Westphal 6e765a009a net_sched: drr: warn when qdisc is not work conserving
The DRR scheduler requires that items on the active list are work
conserving, i.e. do not hold on to skbs for throttling purposes, etc.
Attaching e.g. tbf renders DRR useless because all other classes on the
active list are delayed as well.

So, warn users that this configuration won't work as expected; we
already do this in couple of other qdiscs, see e.g.

commit b00355db3f
('pkt_sched: sch_hfsc: sch_htb: Add non-work-conserving warning handler')

The 'const' change is needed to avoid compiler warning ("discards 'const'
qualifier from pointer target type").

tested with:
drr_hier() {
        parent=$1
        classes=$2
        for i in  $(seq 1 $classes); do
                classid=$parent$(printf %x $i)
                tc class add dev eth0 parent $parent classid $classid drr
		tc qdisc add dev eth0 parent $classid tbf rate 64kbit burst 256kbit limit 64kbit
        done
}
tc qdisc add dev eth0 root handle 1: drr
drr_hier 1: 32
tc filter add dev eth0 protocol all pref 1 parent 1: handle 1 flow hash keys dst perturb 1 divisor 32

Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: David S. Miller <davem@davemloft.net>
2014-06-11 15:50:59 -07:00

527 lines
11 KiB
C

/*
* net/sched/sch_drr.c Deficit Round Robin scheduler
*
* Copyright (c) 2008 Patrick McHardy <kaber@trash.net>
*
* 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.
*/
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/init.h>
#include <linux/errno.h>
#include <linux/netdevice.h>
#include <linux/pkt_sched.h>
#include <net/sch_generic.h>
#include <net/pkt_sched.h>
#include <net/pkt_cls.h>
struct drr_class {
struct Qdisc_class_common common;
unsigned int refcnt;
unsigned int filter_cnt;
struct gnet_stats_basic_packed bstats;
struct gnet_stats_queue qstats;
struct gnet_stats_rate_est64 rate_est;
struct list_head alist;
struct Qdisc *qdisc;
u32 quantum;
u32 deficit;
};
struct drr_sched {
struct list_head active;
struct tcf_proto *filter_list;
struct Qdisc_class_hash clhash;
};
static struct drr_class *drr_find_class(struct Qdisc *sch, u32 classid)
{
struct drr_sched *q = qdisc_priv(sch);
struct Qdisc_class_common *clc;
clc = qdisc_class_find(&q->clhash, classid);
if (clc == NULL)
return NULL;
return container_of(clc, struct drr_class, common);
}
static void drr_purge_queue(struct drr_class *cl)
{
unsigned int len = cl->qdisc->q.qlen;
qdisc_reset(cl->qdisc);
qdisc_tree_decrease_qlen(cl->qdisc, len);
}
static const struct nla_policy drr_policy[TCA_DRR_MAX + 1] = {
[TCA_DRR_QUANTUM] = { .type = NLA_U32 },
};
static int drr_change_class(struct Qdisc *sch, u32 classid, u32 parentid,
struct nlattr **tca, unsigned long *arg)
{
struct drr_sched *q = qdisc_priv(sch);
struct drr_class *cl = (struct drr_class *)*arg;
struct nlattr *opt = tca[TCA_OPTIONS];
struct nlattr *tb[TCA_DRR_MAX + 1];
u32 quantum;
int err;
if (!opt)
return -EINVAL;
err = nla_parse_nested(tb, TCA_DRR_MAX, opt, drr_policy);
if (err < 0)
return err;
if (tb[TCA_DRR_QUANTUM]) {
quantum = nla_get_u32(tb[TCA_DRR_QUANTUM]);
if (quantum == 0)
return -EINVAL;
} else
quantum = psched_mtu(qdisc_dev(sch));
if (cl != NULL) {
if (tca[TCA_RATE]) {
err = gen_replace_estimator(&cl->bstats, &cl->rate_est,
qdisc_root_sleeping_lock(sch),
tca[TCA_RATE]);
if (err)
return err;
}
sch_tree_lock(sch);
if (tb[TCA_DRR_QUANTUM])
cl->quantum = quantum;
sch_tree_unlock(sch);
return 0;
}
cl = kzalloc(sizeof(struct drr_class), GFP_KERNEL);
if (cl == NULL)
return -ENOBUFS;
cl->refcnt = 1;
cl->common.classid = classid;
cl->quantum = quantum;
cl->qdisc = qdisc_create_dflt(sch->dev_queue,
&pfifo_qdisc_ops, classid);
if (cl->qdisc == NULL)
cl->qdisc = &noop_qdisc;
if (tca[TCA_RATE]) {
err = gen_replace_estimator(&cl->bstats, &cl->rate_est,
qdisc_root_sleeping_lock(sch),
tca[TCA_RATE]);
if (err) {
qdisc_destroy(cl->qdisc);
kfree(cl);
return err;
}
}
sch_tree_lock(sch);
qdisc_class_hash_insert(&q->clhash, &cl->common);
sch_tree_unlock(sch);
qdisc_class_hash_grow(sch, &q->clhash);
*arg = (unsigned long)cl;
return 0;
}
static void drr_destroy_class(struct Qdisc *sch, struct drr_class *cl)
{
gen_kill_estimator(&cl->bstats, &cl->rate_est);
qdisc_destroy(cl->qdisc);
kfree(cl);
}
static int drr_delete_class(struct Qdisc *sch, unsigned long arg)
{
struct drr_sched *q = qdisc_priv(sch);
struct drr_class *cl = (struct drr_class *)arg;
if (cl->filter_cnt > 0)
return -EBUSY;
sch_tree_lock(sch);
drr_purge_queue(cl);
qdisc_class_hash_remove(&q->clhash, &cl->common);
BUG_ON(--cl->refcnt == 0);
/*
* This shouldn't happen: we "hold" one cops->get() when called
* from tc_ctl_tclass; the destroy method is done from cops->put().
*/
sch_tree_unlock(sch);
return 0;
}
static unsigned long drr_get_class(struct Qdisc *sch, u32 classid)
{
struct drr_class *cl = drr_find_class(sch, classid);
if (cl != NULL)
cl->refcnt++;
return (unsigned long)cl;
}
static void drr_put_class(struct Qdisc *sch, unsigned long arg)
{
struct drr_class *cl = (struct drr_class *)arg;
if (--cl->refcnt == 0)
drr_destroy_class(sch, cl);
}
static struct tcf_proto **drr_tcf_chain(struct Qdisc *sch, unsigned long cl)
{
struct drr_sched *q = qdisc_priv(sch);
if (cl)
return NULL;
return &q->filter_list;
}
static unsigned long drr_bind_tcf(struct Qdisc *sch, unsigned long parent,
u32 classid)
{
struct drr_class *cl = drr_find_class(sch, classid);
if (cl != NULL)
cl->filter_cnt++;
return (unsigned long)cl;
}
static void drr_unbind_tcf(struct Qdisc *sch, unsigned long arg)
{
struct drr_class *cl = (struct drr_class *)arg;
cl->filter_cnt--;
}
static int drr_graft_class(struct Qdisc *sch, unsigned long arg,
struct Qdisc *new, struct Qdisc **old)
{
struct drr_class *cl = (struct drr_class *)arg;
if (new == NULL) {
new = qdisc_create_dflt(sch->dev_queue,
&pfifo_qdisc_ops, cl->common.classid);
if (new == NULL)
new = &noop_qdisc;
}
sch_tree_lock(sch);
drr_purge_queue(cl);
*old = cl->qdisc;
cl->qdisc = new;
sch_tree_unlock(sch);
return 0;
}
static struct Qdisc *drr_class_leaf(struct Qdisc *sch, unsigned long arg)
{
struct drr_class *cl = (struct drr_class *)arg;
return cl->qdisc;
}
static void drr_qlen_notify(struct Qdisc *csh, unsigned long arg)
{
struct drr_class *cl = (struct drr_class *)arg;
if (cl->qdisc->q.qlen == 0)
list_del(&cl->alist);
}
static int drr_dump_class(struct Qdisc *sch, unsigned long arg,
struct sk_buff *skb, struct tcmsg *tcm)
{
struct drr_class *cl = (struct drr_class *)arg;
struct nlattr *nest;
tcm->tcm_parent = TC_H_ROOT;
tcm->tcm_handle = cl->common.classid;
tcm->tcm_info = cl->qdisc->handle;
nest = nla_nest_start(skb, TCA_OPTIONS);
if (nest == NULL)
goto nla_put_failure;
if (nla_put_u32(skb, TCA_DRR_QUANTUM, cl->quantum))
goto nla_put_failure;
return nla_nest_end(skb, nest);
nla_put_failure:
nla_nest_cancel(skb, nest);
return -EMSGSIZE;
}
static int drr_dump_class_stats(struct Qdisc *sch, unsigned long arg,
struct gnet_dump *d)
{
struct drr_class *cl = (struct drr_class *)arg;
struct tc_drr_stats xstats;
memset(&xstats, 0, sizeof(xstats));
if (cl->qdisc->q.qlen) {
xstats.deficit = cl->deficit;
cl->qdisc->qstats.qlen = cl->qdisc->q.qlen;
}
if (gnet_stats_copy_basic(d, &cl->bstats) < 0 ||
gnet_stats_copy_rate_est(d, &cl->bstats, &cl->rate_est) < 0 ||
gnet_stats_copy_queue(d, &cl->qdisc->qstats) < 0)
return -1;
return gnet_stats_copy_app(d, &xstats, sizeof(xstats));
}
static void drr_walk(struct Qdisc *sch, struct qdisc_walker *arg)
{
struct drr_sched *q = qdisc_priv(sch);
struct drr_class *cl;
unsigned int i;
if (arg->stop)
return;
for (i = 0; i < q->clhash.hashsize; i++) {
hlist_for_each_entry(cl, &q->clhash.hash[i], common.hnode) {
if (arg->count < arg->skip) {
arg->count++;
continue;
}
if (arg->fn(sch, (unsigned long)cl, arg) < 0) {
arg->stop = 1;
return;
}
arg->count++;
}
}
}
static struct drr_class *drr_classify(struct sk_buff *skb, struct Qdisc *sch,
int *qerr)
{
struct drr_sched *q = qdisc_priv(sch);
struct drr_class *cl;
struct tcf_result res;
int result;
if (TC_H_MAJ(skb->priority ^ sch->handle) == 0) {
cl = drr_find_class(sch, skb->priority);
if (cl != NULL)
return cl;
}
*qerr = NET_XMIT_SUCCESS | __NET_XMIT_BYPASS;
result = tc_classify(skb, q->filter_list, &res);
if (result >= 0) {
#ifdef CONFIG_NET_CLS_ACT
switch (result) {
case TC_ACT_QUEUED:
case TC_ACT_STOLEN:
*qerr = NET_XMIT_SUCCESS | __NET_XMIT_STOLEN;
case TC_ACT_SHOT:
return NULL;
}
#endif
cl = (struct drr_class *)res.class;
if (cl == NULL)
cl = drr_find_class(sch, res.classid);
return cl;
}
return NULL;
}
static int drr_enqueue(struct sk_buff *skb, struct Qdisc *sch)
{
struct drr_sched *q = qdisc_priv(sch);
struct drr_class *cl;
int err = 0;
cl = drr_classify(skb, sch, &err);
if (cl == NULL) {
if (err & __NET_XMIT_BYPASS)
sch->qstats.drops++;
kfree_skb(skb);
return err;
}
err = qdisc_enqueue(skb, cl->qdisc);
if (unlikely(err != NET_XMIT_SUCCESS)) {
if (net_xmit_drop_count(err)) {
cl->qstats.drops++;
sch->qstats.drops++;
}
return err;
}
if (cl->qdisc->q.qlen == 1) {
list_add_tail(&cl->alist, &q->active);
cl->deficit = cl->quantum;
}
sch->q.qlen++;
return err;
}
static struct sk_buff *drr_dequeue(struct Qdisc *sch)
{
struct drr_sched *q = qdisc_priv(sch);
struct drr_class *cl;
struct sk_buff *skb;
unsigned int len;
if (list_empty(&q->active))
goto out;
while (1) {
cl = list_first_entry(&q->active, struct drr_class, alist);
skb = cl->qdisc->ops->peek(cl->qdisc);
if (skb == NULL) {
qdisc_warn_nonwc(__func__, cl->qdisc);
goto out;
}
len = qdisc_pkt_len(skb);
if (len <= cl->deficit) {
cl->deficit -= len;
skb = qdisc_dequeue_peeked(cl->qdisc);
if (cl->qdisc->q.qlen == 0)
list_del(&cl->alist);
bstats_update(&cl->bstats, skb);
qdisc_bstats_update(sch, skb);
sch->q.qlen--;
return skb;
}
cl->deficit += cl->quantum;
list_move_tail(&cl->alist, &q->active);
}
out:
return NULL;
}
static unsigned int drr_drop(struct Qdisc *sch)
{
struct drr_sched *q = qdisc_priv(sch);
struct drr_class *cl;
unsigned int len;
list_for_each_entry(cl, &q->active, alist) {
if (cl->qdisc->ops->drop) {
len = cl->qdisc->ops->drop(cl->qdisc);
if (len > 0) {
sch->q.qlen--;
if (cl->qdisc->q.qlen == 0)
list_del(&cl->alist);
return len;
}
}
}
return 0;
}
static int drr_init_qdisc(struct Qdisc *sch, struct nlattr *opt)
{
struct drr_sched *q = qdisc_priv(sch);
int err;
err = qdisc_class_hash_init(&q->clhash);
if (err < 0)
return err;
INIT_LIST_HEAD(&q->active);
return 0;
}
static void drr_reset_qdisc(struct Qdisc *sch)
{
struct drr_sched *q = qdisc_priv(sch);
struct drr_class *cl;
unsigned int i;
for (i = 0; i < q->clhash.hashsize; i++) {
hlist_for_each_entry(cl, &q->clhash.hash[i], common.hnode) {
if (cl->qdisc->q.qlen)
list_del(&cl->alist);
qdisc_reset(cl->qdisc);
}
}
sch->q.qlen = 0;
}
static void drr_destroy_qdisc(struct Qdisc *sch)
{
struct drr_sched *q = qdisc_priv(sch);
struct drr_class *cl;
struct hlist_node *next;
unsigned int i;
tcf_destroy_chain(&q->filter_list);
for (i = 0; i < q->clhash.hashsize; i++) {
hlist_for_each_entry_safe(cl, next, &q->clhash.hash[i],
common.hnode)
drr_destroy_class(sch, cl);
}
qdisc_class_hash_destroy(&q->clhash);
}
static const struct Qdisc_class_ops drr_class_ops = {
.change = drr_change_class,
.delete = drr_delete_class,
.get = drr_get_class,
.put = drr_put_class,
.tcf_chain = drr_tcf_chain,
.bind_tcf = drr_bind_tcf,
.unbind_tcf = drr_unbind_tcf,
.graft = drr_graft_class,
.leaf = drr_class_leaf,
.qlen_notify = drr_qlen_notify,
.dump = drr_dump_class,
.dump_stats = drr_dump_class_stats,
.walk = drr_walk,
};
static struct Qdisc_ops drr_qdisc_ops __read_mostly = {
.cl_ops = &drr_class_ops,
.id = "drr",
.priv_size = sizeof(struct drr_sched),
.enqueue = drr_enqueue,
.dequeue = drr_dequeue,
.peek = qdisc_peek_dequeued,
.drop = drr_drop,
.init = drr_init_qdisc,
.reset = drr_reset_qdisc,
.destroy = drr_destroy_qdisc,
.owner = THIS_MODULE,
};
static int __init drr_init(void)
{
return register_qdisc(&drr_qdisc_ops);
}
static void __exit drr_exit(void)
{
unregister_qdisc(&drr_qdisc_ops);
}
module_init(drr_init);
module_exit(drr_exit);
MODULE_LICENSE("GPL");