linux/net/sched/sch_gred.c
Thomas Graf bdc450a0bb [PKT_SCHED]: (G)RED: Introduce hard dropping
Introduces a new flag TC_RED_HARDDROP which specifies that if ECN
marking is enabled packets should still be dropped once the
average queue length exceeds the maximum threshold.

This _may_ help to avoid global synchronisation during small
bursts of peers advertising but not caring about ECN. Use this
option very carefully, it does more harm than good if
(qth_max - qth_min) does not cover at least two average burst
cycles.

The difference to the current behaviour, in which we'd run into
the hard queue limit, is that due to the low pass filter of RED
short bursts are less likely to cause a global synchronisation.

Signed-off-by: Thomas Graf <tgraf@suug.ch>
Signed-off-by: Arnaldo Carvalho de Melo <acme@mandriva.com>
2005-11-05 22:02:29 +01:00

612 lines
14 KiB
C

/*
* net/sched/sch_gred.c Generic Random Early Detection 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: J Hadi Salim (hadi@cyberus.ca) 1998-2002
*
* 991129: - Bug fix with grio mode
* - a better sing. AvgQ mode with Grio(WRED)
* - A finer grained VQ dequeue based on sugestion
* from Ren Liu
* - More error checks
*
* For all the glorious comments look at include/net/red.h
*/
#include <linux/config.h>
#include <linux/module.h>
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/netdevice.h>
#include <linux/skbuff.h>
#include <net/pkt_sched.h>
#include <net/red.h>
#define GRED_DEF_PRIO (MAX_DPs / 2)
#define GRED_VQ_MASK (MAX_DPs - 1)
struct gred_sched_data;
struct gred_sched;
struct gred_sched_data
{
u32 limit; /* HARD maximal queue length */
u32 DP; /* the drop pramaters */
u32 bytesin; /* bytes seen on virtualQ so far*/
u32 packetsin; /* packets seen on virtualQ so far*/
u32 backlog; /* bytes on the virtualQ */
u8 prio; /* the prio of this vq */
struct red_parms parms;
struct red_stats stats;
};
enum {
GRED_WRED_MODE = 1,
GRED_RIO_MODE,
};
struct gred_sched
{
struct gred_sched_data *tab[MAX_DPs];
unsigned long flags;
u32 red_flags;
u32 DPs;
u32 def;
struct red_parms wred_set;
};
static inline int gred_wred_mode(struct gred_sched *table)
{
return test_bit(GRED_WRED_MODE, &table->flags);
}
static inline void gred_enable_wred_mode(struct gred_sched *table)
{
__set_bit(GRED_WRED_MODE, &table->flags);
}
static inline void gred_disable_wred_mode(struct gred_sched *table)
{
__clear_bit(GRED_WRED_MODE, &table->flags);
}
static inline int gred_rio_mode(struct gred_sched *table)
{
return test_bit(GRED_RIO_MODE, &table->flags);
}
static inline void gred_enable_rio_mode(struct gred_sched *table)
{
__set_bit(GRED_RIO_MODE, &table->flags);
}
static inline void gred_disable_rio_mode(struct gred_sched *table)
{
__clear_bit(GRED_RIO_MODE, &table->flags);
}
static inline int gred_wred_mode_check(struct Qdisc *sch)
{
struct gred_sched *table = qdisc_priv(sch);
int i;
/* Really ugly O(n^2) but shouldn't be necessary too frequent. */
for (i = 0; i < table->DPs; i++) {
struct gred_sched_data *q = table->tab[i];
int n;
if (q == NULL)
continue;
for (n = 0; n < table->DPs; n++)
if (table->tab[n] && table->tab[n] != q &&
table->tab[n]->prio == q->prio)
return 1;
}
return 0;
}
static inline unsigned int gred_backlog(struct gred_sched *table,
struct gred_sched_data *q,
struct Qdisc *sch)
{
if (gred_wred_mode(table))
return sch->qstats.backlog;
else
return q->backlog;
}
static inline u16 tc_index_to_dp(struct sk_buff *skb)
{
return skb->tc_index & GRED_VQ_MASK;
}
static inline void gred_load_wred_set(struct gred_sched *table,
struct gred_sched_data *q)
{
q->parms.qavg = table->wred_set.qavg;
q->parms.qidlestart = table->wred_set.qidlestart;
}
static inline void gred_store_wred_set(struct gred_sched *table,
struct gred_sched_data *q)
{
table->wred_set.qavg = q->parms.qavg;
}
static inline int gred_use_ecn(struct gred_sched *t)
{
return t->red_flags & TC_RED_ECN;
}
static inline int gred_use_harddrop(struct gred_sched *t)
{
return t->red_flags & TC_RED_HARDDROP;
}
static int gred_enqueue(struct sk_buff *skb, struct Qdisc* sch)
{
struct gred_sched_data *q=NULL;
struct gred_sched *t= qdisc_priv(sch);
unsigned long qavg = 0;
u16 dp = tc_index_to_dp(skb);
if (dp >= t->DPs || (q = t->tab[dp]) == NULL) {
dp = t->def;
if ((q = t->tab[dp]) == NULL) {
/* Pass through packets not assigned to a DP
* if no default DP has been configured. This
* allows for DP flows to be left untouched.
*/
if (skb_queue_len(&sch->q) < sch->dev->tx_queue_len)
return qdisc_enqueue_tail(skb, sch);
else
goto drop;
}
/* fix tc_index? --could be controvesial but needed for
requeueing */
skb->tc_index = (skb->tc_index & ~GRED_VQ_MASK) | dp;
}
/* sum up all the qaves of prios <= to ours to get the new qave */
if (!gred_wred_mode(t) && gred_rio_mode(t)) {
int i;
for (i = 0; i < t->DPs; i++) {
if (t->tab[i] && t->tab[i]->prio < q->prio &&
!red_is_idling(&t->tab[i]->parms))
qavg +=t->tab[i]->parms.qavg;
}
}
q->packetsin++;
q->bytesin += skb->len;
if (gred_wred_mode(t))
gred_load_wred_set(t, q);
q->parms.qavg = red_calc_qavg(&q->parms, gred_backlog(t, q, sch));
if (red_is_idling(&q->parms))
red_end_of_idle_period(&q->parms);
if (gred_wred_mode(t))
gred_store_wred_set(t, q);
switch (red_action(&q->parms, q->parms.qavg + qavg)) {
case RED_DONT_MARK:
break;
case RED_PROB_MARK:
sch->qstats.overlimits++;
if (!gred_use_ecn(t) || !INET_ECN_set_ce(skb)) {
q->stats.prob_drop++;
goto congestion_drop;
}
q->stats.prob_mark++;
break;
case RED_HARD_MARK:
sch->qstats.overlimits++;
if (gred_use_harddrop(t) || !gred_use_ecn(t) ||
!INET_ECN_set_ce(skb)) {
q->stats.forced_drop++;
goto congestion_drop;
}
q->stats.forced_mark++;
break;
}
if (q->backlog + skb->len <= q->limit) {
q->backlog += skb->len;
return qdisc_enqueue_tail(skb, sch);
}
q->stats.pdrop++;
drop:
return qdisc_drop(skb, sch);
congestion_drop:
qdisc_drop(skb, sch);
return NET_XMIT_CN;
}
static int gred_requeue(struct sk_buff *skb, struct Qdisc* sch)
{
struct gred_sched *t = qdisc_priv(sch);
struct gred_sched_data *q;
u16 dp = tc_index_to_dp(skb);
if (dp >= t->DPs || (q = t->tab[dp]) == NULL) {
if (net_ratelimit())
printk(KERN_WARNING "GRED: Unable to relocate VQ 0x%x "
"for requeue, screwing up backlog.\n",
tc_index_to_dp(skb));
} else {
if (red_is_idling(&q->parms))
red_end_of_idle_period(&q->parms);
q->backlog += skb->len;
}
return qdisc_requeue(skb, sch);
}
static struct sk_buff *gred_dequeue(struct Qdisc* sch)
{
struct sk_buff *skb;
struct gred_sched *t = qdisc_priv(sch);
skb = qdisc_dequeue_head(sch);
if (skb) {
struct gred_sched_data *q;
u16 dp = tc_index_to_dp(skb);
if (dp >= t->DPs || (q = t->tab[dp]) == NULL) {
if (net_ratelimit())
printk(KERN_WARNING "GRED: Unable to relocate "
"VQ 0x%x after dequeue, screwing up "
"backlog.\n", tc_index_to_dp(skb));
} else {
q->backlog -= skb->len;
if (!q->backlog && !gred_wred_mode(t))
red_start_of_idle_period(&q->parms);
}
return skb;
}
if (gred_wred_mode(t) && !red_is_idling(&t->wred_set))
red_start_of_idle_period(&t->wred_set);
return NULL;
}
static unsigned int gred_drop(struct Qdisc* sch)
{
struct sk_buff *skb;
struct gred_sched *t = qdisc_priv(sch);
skb = qdisc_dequeue_tail(sch);
if (skb) {
unsigned int len = skb->len;
struct gred_sched_data *q;
u16 dp = tc_index_to_dp(skb);
if (dp >= t->DPs || (q = t->tab[dp]) == NULL) {
if (net_ratelimit())
printk(KERN_WARNING "GRED: Unable to relocate "
"VQ 0x%x while dropping, screwing up "
"backlog.\n", tc_index_to_dp(skb));
} else {
q->backlog -= len;
q->stats.other++;
if (!q->backlog && !gred_wred_mode(t))
red_start_of_idle_period(&q->parms);
}
qdisc_drop(skb, sch);
return len;
}
if (gred_wred_mode(t) && !red_is_idling(&t->wred_set))
red_start_of_idle_period(&t->wred_set);
return 0;
}
static void gred_reset(struct Qdisc* sch)
{
int i;
struct gred_sched *t = qdisc_priv(sch);
qdisc_reset_queue(sch);
for (i = 0; i < t->DPs; i++) {
struct gred_sched_data *q = t->tab[i];
if (!q)
continue;
red_restart(&q->parms);
q->backlog = 0;
}
}
static inline void gred_destroy_vq(struct gred_sched_data *q)
{
kfree(q);
}
static inline int gred_change_table_def(struct Qdisc *sch, struct rtattr *dps)
{
struct gred_sched *table = qdisc_priv(sch);
struct tc_gred_sopt *sopt;
int i;
if (dps == NULL || RTA_PAYLOAD(dps) < sizeof(*sopt))
return -EINVAL;
sopt = RTA_DATA(dps);
if (sopt->DPs > MAX_DPs || sopt->DPs == 0 || sopt->def_DP >= sopt->DPs)
return -EINVAL;
sch_tree_lock(sch);
table->DPs = sopt->DPs;
table->def = sopt->def_DP;
table->red_flags = sopt->flags;
/*
* Every entry point to GRED is synchronized with the above code
* and the DP is checked against DPs, i.e. shadowed VQs can no
* longer be found so we can unlock right here.
*/
sch_tree_unlock(sch);
if (sopt->grio) {
gred_enable_rio_mode(table);
gred_disable_wred_mode(table);
if (gred_wred_mode_check(sch))
gred_enable_wred_mode(table);
} else {
gred_disable_rio_mode(table);
gred_disable_wred_mode(table);
}
for (i = table->DPs; i < MAX_DPs; i++) {
if (table->tab[i]) {
printk(KERN_WARNING "GRED: Warning: Destroying "
"shadowed VQ 0x%x\n", i);
gred_destroy_vq(table->tab[i]);
table->tab[i] = NULL;
}
}
return 0;
}
static inline int gred_change_vq(struct Qdisc *sch, int dp,
struct tc_gred_qopt *ctl, int prio, u8 *stab)
{
struct gred_sched *table = qdisc_priv(sch);
struct gred_sched_data *q;
if (table->tab[dp] == NULL) {
table->tab[dp] = kmalloc(sizeof(*q), GFP_KERNEL);
if (table->tab[dp] == NULL)
return -ENOMEM;
memset(table->tab[dp], 0, sizeof(*q));
}
q = table->tab[dp];
q->DP = dp;
q->prio = prio;
q->limit = ctl->limit;
if (q->backlog == 0)
red_end_of_idle_period(&q->parms);
red_set_parms(&q->parms,
ctl->qth_min, ctl->qth_max, ctl->Wlog, ctl->Plog,
ctl->Scell_log, stab);
return 0;
}
static int gred_change(struct Qdisc *sch, struct rtattr *opt)
{
struct gred_sched *table = qdisc_priv(sch);
struct tc_gred_qopt *ctl;
struct rtattr *tb[TCA_GRED_MAX];
int err = -EINVAL, prio = GRED_DEF_PRIO;
u8 *stab;
if (opt == NULL || rtattr_parse_nested(tb, TCA_GRED_MAX, opt))
return -EINVAL;
if (tb[TCA_GRED_PARMS-1] == NULL && tb[TCA_GRED_STAB-1] == NULL)
return gred_change_table_def(sch, opt);
if (tb[TCA_GRED_PARMS-1] == NULL ||
RTA_PAYLOAD(tb[TCA_GRED_PARMS-1]) < sizeof(*ctl) ||
tb[TCA_GRED_STAB-1] == NULL ||
RTA_PAYLOAD(tb[TCA_GRED_STAB-1]) < 256)
return -EINVAL;
ctl = RTA_DATA(tb[TCA_GRED_PARMS-1]);
stab = RTA_DATA(tb[TCA_GRED_STAB-1]);
if (ctl->DP >= table->DPs)
goto errout;
if (gred_rio_mode(table)) {
if (ctl->prio == 0) {
int def_prio = GRED_DEF_PRIO;
if (table->tab[table->def])
def_prio = table->tab[table->def]->prio;
printk(KERN_DEBUG "GRED: DP %u does not have a prio "
"setting default to %d\n", ctl->DP, def_prio);
prio = def_prio;
} else
prio = ctl->prio;
}
sch_tree_lock(sch);
err = gred_change_vq(sch, ctl->DP, ctl, prio, stab);
if (err < 0)
goto errout_locked;
if (gred_rio_mode(table)) {
gred_disable_wred_mode(table);
if (gred_wred_mode_check(sch))
gred_enable_wred_mode(table);
}
err = 0;
errout_locked:
sch_tree_unlock(sch);
errout:
return err;
}
static int gred_init(struct Qdisc *sch, struct rtattr *opt)
{
struct rtattr *tb[TCA_GRED_MAX];
if (opt == NULL || rtattr_parse_nested(tb, TCA_GRED_MAX, opt))
return -EINVAL;
if (tb[TCA_GRED_PARMS-1] || tb[TCA_GRED_STAB-1])
return -EINVAL;
return gred_change_table_def(sch, tb[TCA_GRED_DPS-1]);
}
static int gred_dump(struct Qdisc *sch, struct sk_buff *skb)
{
struct gred_sched *table = qdisc_priv(sch);
struct rtattr *parms, *opts = NULL;
int i;
struct tc_gred_sopt sopt = {
.DPs = table->DPs,
.def_DP = table->def,
.grio = gred_rio_mode(table),
.flags = table->red_flags,
};
opts = RTA_NEST(skb, TCA_OPTIONS);
RTA_PUT(skb, TCA_GRED_DPS, sizeof(sopt), &sopt);
parms = RTA_NEST(skb, TCA_GRED_PARMS);
for (i = 0; i < MAX_DPs; i++) {
struct gred_sched_data *q = table->tab[i];
struct tc_gred_qopt opt;
memset(&opt, 0, sizeof(opt));
if (!q) {
/* hack -- fix at some point with proper message
This is how we indicate to tc that there is no VQ
at this DP */
opt.DP = MAX_DPs + i;
goto append_opt;
}
opt.limit = q->limit;
opt.DP = q->DP;
opt.backlog = q->backlog;
opt.prio = q->prio;
opt.qth_min = q->parms.qth_min >> q->parms.Wlog;
opt.qth_max = q->parms.qth_max >> q->parms.Wlog;
opt.Wlog = q->parms.Wlog;
opt.Plog = q->parms.Plog;
opt.Scell_log = q->parms.Scell_log;
opt.other = q->stats.other;
opt.early = q->stats.prob_drop;
opt.forced = q->stats.forced_drop;
opt.pdrop = q->stats.pdrop;
opt.packets = q->packetsin;
opt.bytesin = q->bytesin;
if (gred_wred_mode(table)) {
q->parms.qidlestart =
table->tab[table->def]->parms.qidlestart;
q->parms.qavg = table->tab[table->def]->parms.qavg;
}
opt.qave = red_calc_qavg(&q->parms, q->parms.qavg);
append_opt:
RTA_APPEND(skb, sizeof(opt), &opt);
}
RTA_NEST_END(skb, parms);
return RTA_NEST_END(skb, opts);
rtattr_failure:
return RTA_NEST_CANCEL(skb, opts);
}
static void gred_destroy(struct Qdisc *sch)
{
struct gred_sched *table = qdisc_priv(sch);
int i;
for (i = 0; i < table->DPs; i++) {
if (table->tab[i])
gred_destroy_vq(table->tab[i]);
}
}
static struct Qdisc_ops gred_qdisc_ops = {
.id = "gred",
.priv_size = sizeof(struct gred_sched),
.enqueue = gred_enqueue,
.dequeue = gred_dequeue,
.requeue = gred_requeue,
.drop = gred_drop,
.init = gred_init,
.reset = gred_reset,
.destroy = gred_destroy,
.change = gred_change,
.dump = gred_dump,
.owner = THIS_MODULE,
};
static int __init gred_module_init(void)
{
return register_qdisc(&gred_qdisc_ops);
}
static void __exit gred_module_exit(void)
{
unregister_qdisc(&gred_qdisc_ops);
}
module_init(gred_module_init)
module_exit(gred_module_exit)
MODULE_LICENSE("GPL");