From a4ee70ffec18b568a207d42790ca734356d21dde Mon Sep 17 00:00:00 2001
From: David du Colombier <0intro@gmail.com>
Date: Sat, 17 Sep 1994 00:00:00 +0000
Subject: [PATCH] Plan 9 from Bell Labs 1994-09-17

---
 port/portdat.h |  2 ++
 port/proc.c    | 19 +++++++++++++------
 2 files changed, 15 insertions(+), 6 deletions(-)

diff --git a/port/portdat.h b/port/portdat.h
index da6ba9ae5c3221a964c8fae81e8a756962642a07..18055d7dc223f964e64c481ed80b221ee8717162 100644
--- a/port/portdat.h
+++ b/port/portdat.h
@@ -585,6 +585,8 @@ struct Proc
 	Mach	*mp;		/* machine this process last ran on */
 	ulong	priority;	/* priority level */
 	ulong	basepri;	/* base priority level */
+	ulong	rt;		/* # ticks used since last blocked */
+	ulong	art;		/* avg # ticks used since last blocked */
 	ulong	movetime;	/* last time process switched processors */
 	ulong	readyticks;	/* time process went ready */
 
diff --git a/port/proc.c b/port/proc.c
index 444edecd3774b2de445131d923c2930ac426733f..c9d2f3f4e1b3ec87023c5d7fce2f224474a05d46 100644
--- a/port/proc.c
+++ b/port/proc.c
@@ -124,19 +124,24 @@ anyhigher(void)
 	return nrdy && x >= up->priority;
 }
 
+enum
+{
+	Squantum = (HZ+Nrq-1)/Nrq,
+};
+
 void
 ready(Proc *p)
 {
-	int s;
+	int s, pri;
 	Schedq *rq;
 
 	s = splhi();
 
-	if(p->state == Running){
-		if(p->priority > 0)
-			p->priority--;
-	} else
-		p->priority = p->basepri;
+	if(p->state == Running)
+		p->rt++;
+	pri = p->basepri - (((p->art + p->rt)>>1)/Squantum);
+	if(pri < 0)
+		pri = 0;
 	rq = &runq[p->priority];
 
 	lock(runq);
@@ -330,6 +335,8 @@ sleep1(Rendez *r, int (*f)(void*), void *arg)
 		dumpstack();
 	}
 	up->state = Wakeme;
+	up->art = (up->art + up->rt)>>1;
+	up->rt = 0;
 	r->p = up;
 	unlock(r);
 }