Commit a73ed26b authored by Eric Dumazet's avatar Eric Dumazet Committed by David S. Miller
Browse files

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: default avatarEric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 0221cd51

include/linux/pkt_sched.h

+2 −0
Original line number Diff line number Diff line
@@ -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,

};

include/net/red.h

+11 −5
Original line number Diff line number Diff line
@@ -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

net/sched/sch_choke.c

+7 −1
Original line number Diff line number Diff line
@@ -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:

net/sched/sch_gred.c

+18 −4
Original line number Diff line number Diff line
@@ -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;

net/sched/sch_red.c

+7 −2
Original line number Diff line number Diff line
@@ -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) {
@@ -210,7 +214,8 @@ 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]));

		      nla_data(tb[TCA_RED_STAB]),

		      max_P);



	del_timer(&q->adapt_timer);

	if (ctl->flags & TC_RED_ADAPTATIVE)

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