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sch_red: generalize accurate MAX_P support to RED/GRED/CHOKE 

Now RED uses a Q0.32 number to store max_p (max probability), allow
RED/GRED/CHOKE to use/report full resolution at config/dump time.

Old tc binaries are non aware of new attributes, and still set/get Plog.

New tc binary set/get both Plog and max_p for backward compatibility,
they display "probability value" if they get max_p from new kernels.

# tc -d  qdisc show dev ...
...
qdisc red 10: parent 1:1 limit 360Kb min 30Kb max 90Kb ecn ewma 5
probability 0.09 Scell_log 15

Make sure we avoid potential divides by 0 in reciprocal_value(), if
(max_th - min_th) is big.

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Eric Dumazet 2011-12-09 02:46:45 +00:00 committed by David S. Miller
parent 0221cd5154
commit a73ed26bba
5 changed files with 45 additions and 12 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
include/linux/pkt_sched.h
View File

@ -216,6 +216,7 @@ enum {
TCA_GRED_PARMS,
TCA_GRED_STAB,
TCA_GRED_DPS,
TCA_GRED_MAX_P,
__TCA_GRED_MAX,
};
@ -255,6 +256,7 @@ enum {
TCA_CHOKE_UNSPEC,
TCA_CHOKE_PARMS,
TCA_CHOKE_STAB,
TCA_CHOKE_MAX_P,
__TCA_CHOKE_MAX,
};

16
include/net/red.h
View File

@ -155,9 +155,10 @@ static inline u32 red_maxp(u8 Plog)
static inline void red_set_parms(struct red_parms *p,
u32 qth_min, u32 qth_max, u8 Wlog, u8 Plog,
u8 Scell_log, u8 *stab)
u8 Scell_log, u8 *stab, u32 max_P)
{
int delta = qth_max - qth_min;
u32 max_p_delta;
/* Reset average queue length, the value is strictly bound
* to the parameters below, reseting hurts a bit but leaving
@ -173,10 +174,14 @@ static inline void red_set_parms(struct red_parms *p,
if (delta < 0)
delta = 1;
p->qth_delta = delta;
p->max_P = red_maxp(Plog);
p->max_P *= delta; /* max_P = (qth_max-qth_min)/2^Plog */
p->max_P_reciprocal = reciprocal_value(p->max_P / delta);
if (!max_P) {
max_P = red_maxp(Plog);
max_P *= delta; /* max_P = (qth_max - qth_min)/2^Plog */
}
p->max_P = max_P;
max_p_delta = max_P / delta;
max_p_delta = max(max_p_delta, 1U);
p->max_P_reciprocal = reciprocal_value(max_p_delta);
/* RED Adaptative target :
* [min_th + 0.4*(min_th - max_th),
@ -380,6 +385,7 @@ static inline void red_adaptative_algo(struct red_parms *p)
p->max_P = (p->max_P/10)*9; /* maxp = maxp * Beta */
max_p_delta = DIV_ROUND_CLOSEST(p->max_P, p->qth_delta);
max_p_delta = max(max_p_delta, 1U);
p->max_P_reciprocal = reciprocal_value(max_p_delta);
}
#endif

8
net/sched/sch_choke.c
View File

@ -394,6 +394,7 @@ static void choke_reset(struct Qdisc *sch)
static const struct nla_policy choke_policy[TCA_CHOKE_MAX + 1] = {
[TCA_CHOKE_PARMS] = { .len = sizeof(struct tc_red_qopt) },
[TCA_CHOKE_STAB] = { .len = RED_STAB_SIZE },
[TCA_CHOKE_MAX_P] = { .type = NLA_U32 },
};
@ -415,6 +416,7 @@ static int choke_change(struct Qdisc *sch, struct nlattr *opt)
int err;
struct sk_buff **old = NULL;
unsigned int mask;
u32 max_P;
if (opt == NULL)
return -EINVAL;
@ -427,6 +429,8 @@ static int choke_change(struct Qdisc *sch, struct nlattr *opt)
tb[TCA_CHOKE_STAB] == NULL)
return -EINVAL;
max_P = tb[TCA_CHOKE_MAX_P] ? nla_get_u32(tb[TCA_CHOKE_MAX_P]) : 0;
ctl = nla_data(tb[TCA_CHOKE_PARMS]);
if (ctl->limit > CHOKE_MAX_QUEUE)
@ -476,7 +480,8 @@ static int choke_change(struct Qdisc *sch, struct nlattr *opt)
red_set_parms(&q->parms, ctl->qth_min, ctl->qth_max, ctl->Wlog,
ctl->Plog, ctl->Scell_log,
nla_data(tb[TCA_CHOKE_STAB]));
nla_data(tb[TCA_CHOKE_STAB]),
max_P);
if (q->head == q->tail)
red_end_of_idle_period(&q->parms);
@ -510,6 +515,7 @@ static int choke_dump(struct Qdisc *sch, struct sk_buff *skb)
goto nla_put_failure;
NLA_PUT(skb, TCA_CHOKE_PARMS, sizeof(opt), &opt);
NLA_PUT_U32(skb, TCA_CHOKE_MAX_P, q->parms.max_P);
return nla_nest_end(skb, opts);
nla_put_failure:

22
net/sched/sch_gred.c
View File

@ -34,7 +34,7 @@ struct gred_sched;
struct gred_sched_data {
u32 limit; /* HARD maximal queue length */
u32 DP; /* the drop pramaters */
u32 DP; /* the drop parameters */
u32 bytesin; /* bytes seen on virtualQ so far*/
u32 packetsin; /* packets seen on virtualQ so far*/
u32 backlog; /* bytes on the virtualQ */
@ -379,7 +379,8 @@ static inline int gred_change_table_def(struct Qdisc *sch, struct nlattr *dps)
}
static inline int gred_change_vq(struct Qdisc *sch, int dp,
struct tc_gred_qopt *ctl, int prio, u8 *stab)
struct tc_gred_qopt *ctl, int prio,
u8 *stab, u32 max_P)
{
struct gred_sched *table = qdisc_priv(sch);
struct gred_sched_data *q;
@ -400,7 +401,7 @@ static inline int gred_change_vq(struct Qdisc *sch, int dp,
red_set_parms(&q->parms,
ctl->qth_min, ctl->qth_max, ctl->Wlog, ctl->Plog,
ctl->Scell_log, stab);
ctl->Scell_log, stab, max_P);
return 0;
}
@ -409,6 +410,7 @@ static const struct nla_policy gred_policy[TCA_GRED_MAX + 1] = {
[TCA_GRED_PARMS] = { .len = sizeof(struct tc_gred_qopt) },
[TCA_GRED_STAB] = { .len = 256 },
[TCA_GRED_DPS] = { .len = sizeof(struct tc_gred_sopt) },
[TCA_GRED_MAX_P] = { .type = NLA_U32 },
};
static int gred_change(struct Qdisc *sch, struct nlattr *opt)
@ -418,6 +420,7 @@ static int gred_change(struct Qdisc *sch, struct nlattr *opt)
struct nlattr *tb[TCA_GRED_MAX + 1];
int err, prio = GRED_DEF_PRIO;
u8 *stab;
u32 max_P;
if (opt == NULL)
return -EINVAL;
@ -433,6 +436,8 @@ static int gred_change(struct Qdisc *sch, struct nlattr *opt)
tb[TCA_GRED_STAB] == NULL)
return -EINVAL;
max_P = tb[TCA_GRED_MAX_P] ? nla_get_u32(tb[TCA_GRED_MAX_P]) : 0;
err = -EINVAL;
ctl = nla_data(tb[TCA_GRED_PARMS]);
stab = nla_data(tb[TCA_GRED_STAB]);
@ -457,7 +462,7 @@ static int gred_change(struct Qdisc *sch, struct nlattr *opt)
sch_tree_lock(sch);
err = gred_change_vq(sch, ctl->DP, ctl, prio, stab);
err = gred_change_vq(sch, ctl->DP, ctl, prio, stab, max_P);
if (err < 0)
goto errout_locked;
@ -498,6 +503,7 @@ static int gred_dump(struct Qdisc *sch, struct sk_buff *skb)
struct gred_sched *table = qdisc_priv(sch);
struct nlattr *parms, *opts = NULL;
int i;
u32 max_p[MAX_DPs];
struct tc_gred_sopt sopt = {
.DPs = table->DPs,
.def_DP = table->def,
@ -509,6 +515,14 @@ static int gred_dump(struct Qdisc *sch, struct sk_buff *skb)
if (opts == NULL)
goto nla_put_failure;
NLA_PUT(skb, TCA_GRED_DPS, sizeof(sopt), &sopt);
for (i = 0; i < MAX_DPs; i++) {
struct gred_sched_data *q = table->tab[i];
max_p[i] = q ? q->parms.max_P : 0;
}
NLA_PUT(skb, TCA_GRED_MAX_P, sizeof(max_p), max_p);
parms = nla_nest_start(skb, TCA_GRED_PARMS);
if (parms == NULL)
goto nla_put_failure;

9
net/sched/sch_red.c
View File

@ -170,6 +170,7 @@ static void red_destroy(struct Qdisc *sch)
static const struct nla_policy red_policy[TCA_RED_MAX + 1] = {
[TCA_RED_PARMS] = { .len = sizeof(struct tc_red_qopt) },
[TCA_RED_STAB] = { .len = RED_STAB_SIZE },
[TCA_RED_MAX_P] = { .type = NLA_U32 },
};
static int red_change(struct Qdisc *sch, struct nlattr *opt)
@ -179,6 +180,7 @@ static int red_change(struct Qdisc *sch, struct nlattr *opt)
struct tc_red_qopt *ctl;
struct Qdisc *child = NULL;
int err;
u32 max_P;
if (opt == NULL)
return -EINVAL;
@ -191,6 +193,8 @@ static int red_change(struct Qdisc *sch, struct nlattr *opt)
tb[TCA_RED_STAB] == NULL)
return -EINVAL;
max_P = tb[TCA_RED_MAX_P] ? nla_get_u32(tb[TCA_RED_MAX_P]) : 0;
ctl = nla_data(tb[TCA_RED_PARMS]);
if (ctl->limit > 0) {
@ -209,8 +213,9 @@ static int red_change(struct Qdisc *sch, struct nlattr *opt)
}
red_set_parms(&q->parms, ctl->qth_min, ctl->qth_max, ctl->Wlog,
ctl->Plog, ctl->Scell_log,
nla_data(tb[TCA_RED_STAB]));
ctl->Plog, ctl->Scell_log,
nla_data(tb[TCA_RED_STAB]),
max_P);
del_timer(&q->adapt_timer);
if (ctl->flags & TC_RED_ADAPTATIVE)