[PKT_SCHED]: GRED: Use new generic red interface

Simplifies code a lot by separating the red algorithm and the
queueing logic. We now differentiate between probability marks
and forced marks but sum them together again to not break
backwards compatibility.

This brings GRED back to the level of RED and improves the
accuracy of the averge queue length calculations when stab
suggests a zero shift.
Signed-off-by: Thomas Graf <tgraf@suug.ch>
Signed-off-by: Arnaldo Carvalho de Melo <acme@mandriva.com>

net/sched/sch_gred.c

@@ -45,6 +45,7 @@
 #include <linux/skbuff.h>
 #include <net/sock.h>
 #include <net/pkt_sched.h>
+#include <net/red.h>
 
 #if 1 /* control */
 #define DPRINTK(format,args...) printk(KERN_DEBUG format,##args)
@@ -65,32 +66,15 @@ struct gred_sched;
 
 struct gred_sched_data
 {
-/* Parameters */
 	u32		limit;		/* HARD maximal queue length	*/
-	u32		qth_min;	/* Min average length threshold: A scaled */
-	u32		qth_max;	/* Max average length threshold: A scaled */
 	u32      	DP;		/* the drop pramaters */
-	char		Wlog;		/* log(W)		*/
-	char		Plog;		/* random number bits	*/
-	u32		Scell_max;
-	u32		Rmask;
 	u32		bytesin;	/* bytes seen on virtualQ so far*/
 	u32		packetsin;	/* packets seen on virtualQ so far*/
 	u32		backlog;	/* bytes on the virtualQ */
-	u32		forced;	/* packets dropped for exceeding limits */
-	u32		early;	/* packets dropped as a warning */
-	u32		other;	/* packets dropped by invoking drop() */
-	u32		pdrop;	/* packets dropped because we exceeded physical queue limits */
-	char		Scell_log;
-	u8		Stab[256];
 	u8              prio;        /* the prio of this vq */
 
-/* Variables */
-	unsigned long	qave;		/* Average queue length: A scaled */
-	int		qcount;		/* Packets since last random number generation */
-	u32		qR;		/* Cached random number */
-
-	psched_time_t	qidlestart;	/* Start of idle period	*/
+	struct red_parms parms;
+	struct red_stats stats;
 };
 
 enum {
@@ -159,13 +143,22 @@ static inline int gred_wred_mode_check(struct Qdisc *sch)
 	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 int
 gred_enqueue(struct sk_buff *skb, struct Qdisc* sch)
 {
-	psched_time_t now;
 	struct gred_sched_data *q=NULL;
 	struct gred_sched *t= qdisc_priv(sch);
-	unsigned long	qave=0;	
+	unsigned long qavg = 0;
 	int i=0;
 
 	if (!t->initd && skb_queue_len(&sch->q) < (sch->dev->tx_queue_len ? : 1)) {
@@ -195,8 +188,9 @@ gred_enqueue(struct sk_buff *skb, struct Qdisc* sch)
 			if ((!t->tab[i]) || (i==q->DP))	
 				continue; 
 				
-			if ((t->tab[i]->prio < q->prio) && (PSCHED_IS_PASTPERFECT(t->tab[i]->qidlestart)))
-				qave +=t->tab[i]->qave;
+			if (t->tab[i]->prio < q->prio &&
+			    !red_is_idling(&t->tab[i]->parms))
+				qavg +=t->tab[i]->parms.qavg;
 		}
 			
 	}
@@ -205,68 +199,49 @@ gred_enqueue(struct sk_buff *skb, struct Qdisc* sch)
 	q->bytesin+=skb->len;
 
 	if (gred_wred_mode(t)) {
-		qave=0;
-		q->qave=t->tab[t->def]->qave;
-		q->qidlestart=t->tab[t->def]->qidlestart;
+		qavg = 0;
+		q->parms.qavg = t->tab[t->def]->parms.qavg;
+		q->parms.qidlestart = t->tab[t->def]->parms.qidlestart;
 	}
 
-	if (!PSCHED_IS_PASTPERFECT(q->qidlestart)) {
-		long us_idle;
-		PSCHED_GET_TIME(now);
-		us_idle = PSCHED_TDIFF_SAFE(now, q->qidlestart, q->Scell_max);
-		PSCHED_SET_PASTPERFECT(q->qidlestart);
+	q->parms.qavg = red_calc_qavg(&q->parms, gred_backlog(t, q, sch));
 
-		q->qave >>= q->Stab[(us_idle>>q->Scell_log)&0xFF];
-	} else {
-		if (gred_wred_mode(t)) {
-			q->qave += sch->qstats.backlog - (q->qave >> q->Wlog);
-		} else {
-			q->qave += q->backlog - (q->qave >> q->Wlog);
-		}
-
-	}
-	
+	if (red_is_idling(&q->parms))
+		red_end_of_idle_period(&q->parms);
 
 	if (gred_wred_mode(t))
-		t->tab[t->def]->qave=q->qave;
+		t->tab[t->def]->parms.qavg = q->parms.qavg;
 
-	if ((q->qave+qave) < q->qth_min) {
-		q->qcount = -1;
-enqueue:
-		if (q->backlog + skb->len <= q->limit) {
-			q->backlog += skb->len;
-do_enqueue:
-			__skb_queue_tail(&sch->q, skb);
-			sch->qstats.backlog += skb->len;
-			sch->bstats.bytes += skb->len;
-			sch->bstats.packets++;
-			return 0;
-		} else {
-			q->pdrop++;
-		}
+	switch (red_action(&q->parms, q->parms.qavg + qavg)) {
+		case RED_DONT_MARK:
+			break;
 
-drop:
-		kfree_skb(skb);
-		sch->qstats.drops++;
-		return NET_XMIT_DROP;
-	}
-	if ((q->qave+qave) >= q->qth_max) {
-		q->qcount = -1;
-		sch->qstats.overlimits++;
-		q->forced++;
-		goto drop;
+		case RED_PROB_MARK:
+			sch->qstats.overlimits++;
+			q->stats.prob_drop++;
+			goto drop;
+
+		case RED_HARD_MARK:
+			sch->qstats.overlimits++;
+			q->stats.forced_drop++;
+			goto drop;
 	}
-	if (++q->qcount) {
-		if ((((qave+q->qave) - q->qth_min)>>q->Wlog)*q->qcount < q->qR)
-			goto enqueue;
-		q->qcount = 0;
-		q->qR = net_random()&q->Rmask;
-		sch->qstats.overlimits++;
-		q->early++;
-		goto drop;
+
+	if (q->backlog + skb->len <= q->limit) {
+		q->backlog += skb->len;
+do_enqueue:
+		__skb_queue_tail(&sch->q, skb);
+		sch->qstats.backlog += skb->len;
+		sch->bstats.bytes += skb->len;
+		sch->bstats.packets++;
+		return 0;
 	}
-	q->qR = net_random()&q->Rmask;
-	goto enqueue;
+
+	q->stats.pdrop++;
+drop:
+	kfree_skb(skb);
+	sch->qstats.drops++;
+	return NET_XMIT_DROP;
 }
 
 static int
@@ -276,7 +251,9 @@ gred_requeue(struct sk_buff *skb, struct Qdisc* sch)
 	struct gred_sched *t= qdisc_priv(sch);
 	q= t->tab[(skb->tc_index&0xf)];
 /* error checking here -- probably unnecessary */
-	PSCHED_SET_PASTPERFECT(q->qidlestart);
+
+	if (red_is_idling(&q->parms))
+		red_end_of_idle_period(&q->parms);
 
 	__skb_queue_head(&sch->q, skb);
 	sch->qstats.backlog += skb->len;
@@ -299,7 +276,7 @@ gred_dequeue(struct Qdisc* sch)
 		if (q) {
 			q->backlog -= skb->len;
 			if (!q->backlog && !gred_wred_mode(t))
-				PSCHED_GET_TIME(q->qidlestart);
+				red_start_of_idle_period(&q->parms);
 		} else {
 			D2PRINTK("gred_dequeue: skb has bad tcindex %x\n",skb->tc_index&0xf); 
 		}
@@ -312,7 +289,7 @@ gred_dequeue(struct Qdisc* sch)
 				D2PRINTK("no default VQ set: Results will be "
 				       "screwed up\n");
 			else
-				PSCHED_GET_TIME(q->qidlestart);
+				red_start_of_idle_period(&q->parms);
 	}
 
 	return NULL;
@@ -333,9 +310,9 @@ static unsigned int gred_drop(struct Qdisc* sch)
 		q= t->tab[(skb->tc_index&0xf)];
 		if (q) {
 			q->backlog -= len;
-			q->other++;
+			q->stats.other++;
 			if (!q->backlog && !gred_wred_mode(t))
-				PSCHED_GET_TIME(q->qidlestart);
+				red_start_of_idle_period(&q->parms);
 		} else {
 			D2PRINTK("gred_dequeue: skb has bad tcindex %x\n",skb->tc_index&0xf); 
 		}
@@ -350,7 +327,7 @@ static unsigned int gred_drop(struct Qdisc* sch)
 		return 0;
 	}
 
-	PSCHED_GET_TIME(q->qidlestart);
+	red_start_of_idle_period(&q->parms);
 	return 0;
 
 }
@@ -369,14 +346,12 @@ static void gred_reset(struct Qdisc* sch)
 	        q= t->tab[i];
 		if (!q)	
 			continue; 
-		PSCHED_SET_PASTPERFECT(q->qidlestart);
-		q->qave = 0;
-		q->qcount = -1;
+		red_restart(&q->parms);
 		q->backlog = 0;
-		q->other=0;
-		q->forced=0;
-		q->pdrop=0;
-		q->early=0;
+		q->stats.other = 0;
+		q->stats.forced_drop = 0;
+		q->stats.prob_drop = 0;
+		q->stats.pdrop = 0;
 	}
 }
 
@@ -450,25 +425,19 @@ static inline int gred_change_vq(struct Qdisc *sch, int dp,
 	q = table->tab[dp];
 	q->DP = dp;
 	q->prio = prio;
-
-	q->Wlog = ctl->Wlog;
-	q->Plog = ctl->Plog;
 	q->limit = ctl->limit;
-	q->Scell_log = ctl->Scell_log;
- 	q->Rmask = ctl->Plog < 32 ? ((1<<ctl->Plog) - 1) : ~0UL;
- 	q->Scell_max = (255<<q->Scell_log);
- 	q->qth_min = ctl->qth_min<<ctl->Wlog;
- 	q->qth_max = ctl->qth_max<<ctl->Wlog;
- 	q->qave=0;
- 	q->backlog=0;
- 	q->qcount = -1;
- 	q->other=0;
- 	q->forced=0;
- 	q->pdrop=0;
-	q->early=0;
-
-	PSCHED_SET_PASTPERFECT(q->qidlestart);
-	memcpy(q->Stab, stab, 256);
+
+	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);
+
+	q->stats.other = 0;
+	q->stats.forced_drop = 0;
+	q->stats.prob_drop = 0;
+	q->stats.pdrop = 0;
 
 	return 0;
 }
@@ -592,37 +561,26 @@ static int gred_dump(struct Qdisc *sch, struct sk_buff *skb)
 		opt.DP		= q->DP;
 		opt.backlog	= q->backlog;
 		opt.prio	= q->prio;
-		opt.qth_min	= q->qth_min >> q->Wlog;
-		opt.qth_max	= q->qth_max >> q->Wlog;
-		opt.Wlog	= q->Wlog;
-		opt.Plog	= q->Plog;
-		opt.Scell_log	= q->Scell_log;
-		opt.other	= q->other;
-		opt.early	= q->early;
-		opt.forced	= q->forced;
-		opt.pdrop	= q->pdrop;
+		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 (q->qave) {
-			if (gred_wred_mode(table)) {
-				q->qidlestart=table->tab[table->def]->qidlestart;
-				q->qave=table->tab[table->def]->qave;
-			}
-			if (!PSCHED_IS_PASTPERFECT(q->qidlestart)) {
-				long idle;
-				unsigned long qave;
-				psched_time_t now;
-				PSCHED_GET_TIME(now);
-				idle = PSCHED_TDIFF_SAFE(now, q->qidlestart, q->Scell_max);
-				qave  = q->qave >> q->Stab[(idle>>q->Scell_log)&0xFF];
-				opt.qave = qave >> q->Wlog;
-
-			} else {
-				opt.qave = q->qave >> q->Wlog;
-			}
+		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);
 	}