net_sched: red: split red_parms into parms and vars

This patch splits the red_parms structure into two components.

One holding the RED 'constant' parameters, and one containing the
variables.

This permits a size reduction of GRED qdisc, and is a preliminary step
to add an optional RED unit to SFQ.

SFQRED will have a single red_parms structure shared by all flows, and a
private red_vars per flow.

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
CC: Dave Taht <dave.taht@gmail.com>
CC: Stephen Hemminger <shemminger@vyatta.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 55 insertions, 43 deletions

diff --git a/include/net/red.h b/include/net/red.h
index ef715a16cce4..baab385a4736 100644
--- a/include/net/red.h
+++ b/include/net/red.h
@@ -137,7 +137,9 @@ struct red_parms {
 	u8		Wlog;		/* log(W)		*/
 	u8		Plog;		/* random number bits	*/
 	u8		Stab[RED_STAB_SIZE];
+};
 
+struct red_vars {
 	/* Variables */
 	int		qcount;		/* Number of packets since last random
 					   number generation */
@@ -152,6 +154,16 @@ static inline u32 red_maxp(u8 Plog)
 	return Plog < 32 ? (~0U >> Plog) : ~0U;
 }
 
+static inline void red_set_vars(struct red_vars *v)
+{
+	/* Reset average queue length, the value is strictly bound
+	 * to the parameters below, reseting hurts a bit but leaving
+	 * it might result in an unreasonable qavg for a while. --TGR
+	 */
+	v->qavg		= 0;
+
+	v->qcount	= -1;
+}
 
 static inline void red_set_parms(struct red_parms *p,
 				 u32 qth_min, u32 qth_max, u8 Wlog, u8 Plog,
@@ -160,13 +172,6 @@ static inline void red_set_parms(struct red_parms *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
-	 * it might result in an unreasonable qavg for a while. --TGR
-	 */
-	p->qavg		= 0;
-
-	p->qcount	= -1;
 	p->qth_min	= qth_min << Wlog;
 	p->qth_max	= qth_max << Wlog;
 	p->Wlog		= Wlog;
@@ -197,31 +202,32 @@ static inline void red_set_parms(struct red_parms *p,
 	memcpy(p->Stab, stab, sizeof(p->Stab));
 }
 
-static inline int red_is_idling(const struct red_parms *p)
+static inline int red_is_idling(const struct red_vars *v)
 {
-	return p->qidlestart.tv64 != 0;
+	return v->qidlestart.tv64 != 0;
 }
 
-static inline void red_start_of_idle_period(struct red_parms *p)
+static inline void red_start_of_idle_period(struct red_vars *v)
 {
-	p->qidlestart = ktime_get();
+	v->qidlestart = ktime_get();
 }
 
-static inline void red_end_of_idle_period(struct red_parms *p)
+static inline void red_end_of_idle_period(struct red_vars *v)
 {
-	p->qidlestart.tv64 = 0;
+	v->qidlestart.tv64 = 0;
 }
 
-static inline void red_restart(struct red_parms *p)
+static inline void red_restart(struct red_vars *v)
 {
-	red_end_of_idle_period(p);
-	p->qavg = 0;
-	p->qcount = -1;
+	red_end_of_idle_period(v);
+	v->qavg = 0;
+	v->qcount = -1;
 }
 
-static inline unsigned long red_calc_qavg_from_idle_time(const struct red_parms *p)
+static inline unsigned long red_calc_qavg_from_idle_time(const struct red_parms *p,
+							 const struct red_vars *v)
 {
-	s64 delta = ktime_us_delta(ktime_get(), p->qidlestart);
+	s64 delta = ktime_us_delta(ktime_get(), v->qidlestart);
 	long us_idle = min_t(s64, delta, p->Scell_max);
 	int  shift;
 
@@ -248,7 +254,7 @@ static inline unsigned long red_calc_qavg_from_idle_time(const struct red_parms
 	shift = p->Stab[(us_idle >> p->Scell_log) & RED_STAB_MASK];
 
 	if (shift)
-		return p->qavg >> shift;
+		return v->qavg >> shift;
 	else {
 		/* Approximate initial part of exponent with linear function:
 		 *
@@ -257,16 +263,17 @@ static inline unsigned long red_calc_qavg_from_idle_time(const struct red_parms
 		 * Seems, it is the best solution to
 		 * problem of too coarse exponent tabulation.
 		 */
-		us_idle = (p->qavg * (u64)us_idle) >> p->Scell_log;
+		us_idle = (v->qavg * (u64)us_idle) >> p->Scell_log;
 
-		if (us_idle < (p->qavg >> 1))
-			return p->qavg - us_idle;
+		if (us_idle < (v->qavg >> 1))
+			return v->qavg - us_idle;
 		else
-			return p->qavg >> 1;
+			return v->qavg >> 1;
 	}
 }
 
 static inline unsigned long red_calc_qavg_no_idle_time(const struct red_parms *p,
+						       const struct red_vars *v,
 						       unsigned int backlog)
 {
 	/*
@@ -278,16 +285,17 @@ static inline unsigned long red_calc_qavg_no_idle_time(const struct red_parms *p
 	 *
 	 * --ANK (980924)
 	 */
-	return p->qavg + (backlog - (p->qavg >> p->Wlog));
+	return v->qavg + (backlog - (v->qavg >> p->Wlog));
 }
 
 static inline unsigned long red_calc_qavg(const struct red_parms *p,
+					  const struct red_vars *v,
 					  unsigned int backlog)
 {
-	if (!red_is_idling(p))
-		return red_calc_qavg_no_idle_time(p, backlog);
+	if (!red_is_idling(v))
+		return red_calc_qavg_no_idle_time(p, v, backlog);
 	else
-		return red_calc_qavg_from_idle_time(p);
+		return red_calc_qavg_from_idle_time(p, v);
 }
 
 
@@ -296,7 +304,9 @@ static inline u32 red_random(const struct red_parms *p)
 	return reciprocal_divide(net_random(), p->max_P_reciprocal);
 }
 
-static inline int red_mark_probability(const struct red_parms *p, unsigned long qavg)
+static inline int red_mark_probability(const struct red_parms *p,
+				       const struct red_vars *v,
+				       unsigned long qavg)
 {
 	/* The formula used below causes questions.
 
@@ -314,7 +324,7 @@ static inline int red_mark_probability(const struct red_parms *p, unsigned long
 
 	   Any questions? --ANK (980924)
 	 */
-	return !(((qavg - p->qth_min) >> p->Wlog) * p->qcount < p->qR);
+	return !(((qavg - p->qth_min) >> p->Wlog) * v->qcount < v->qR);
 }
 
 enum {
@@ -323,7 +333,7 @@ enum {
 	RED_ABOVE_MAX_TRESH,
 };
 
-static inline int red_cmp_thresh(struct red_parms *p, unsigned long qavg)
+static inline int red_cmp_thresh(const struct red_parms *p, unsigned long qavg)
 {
 	if (qavg < p->qth_min)
 		return RED_BELOW_MIN_THRESH;
@@ -339,27 +349,29 @@ enum {
 	RED_HARD_MARK,
 };
 
-static inline int red_action(struct red_parms *p, unsigned long qavg)
+static inline int red_action(const struct red_parms *p,
+			     struct red_vars *v,
+			     unsigned long qavg)
 {
 	switch (red_cmp_thresh(p, qavg)) {
 		case RED_BELOW_MIN_THRESH:
-			p->qcount = -1;
+			v->qcount = -1;
 			return RED_DONT_MARK;
 
 		case RED_BETWEEN_TRESH:
-			if (++p->qcount) {
-				if (red_mark_probability(p, qavg)) {
-					p->qcount = 0;
-					p->qR = red_random(p);
+			if (++v->qcount) {
+				if (red_mark_probability(p, v, qavg)) {
+					v->qcount = 0;
+					v->qR = red_random(p);
 					return RED_PROB_MARK;
 				}
 			} else
-				p->qR = red_random(p);
+				v->qR = red_random(p);
 
 			return RED_DONT_MARK;
 
 		case RED_ABOVE_MAX_TRESH:
-			p->qcount = -1;
+			v->qcount = -1;
 			return RED_HARD_MARK;
 	}
 
@@ -367,14 +379,14 @@ static inline int red_action(struct red_parms *p, unsigned long qavg)
 	return RED_DONT_MARK;
 }
 
-static inline void red_adaptative_algo(struct red_parms *p)
+static inline void red_adaptative_algo(struct red_parms *p, struct red_vars *v)
 {
 	unsigned long qavg;
 	u32 max_p_delta;
 
-	qavg = p->qavg;
-	if (red_is_idling(p))
-		qavg = red_calc_qavg_from_idle_time(p);
+	qavg = v->qavg;
+	if (red_is_idling(v))
+		qavg = red_calc_qavg_from_idle_time(p, v);
 
 	/* p->qavg is fixed point number with point at Wlog */
 	qavg >>= p->Wlog;