From 8b57a227f50123822c311592ed997d999c2e1b85 Mon Sep 17 00:00:00 2001
From: David du Colombier <0intro@gmail.com>
Date: Wed, 18 Dec 2002 00:00:00 +0000
Subject: [PATCH] Plan 9 from Bell Labs 2002-12-18

---
 pc/i8253.c |  6 +++++-
 pc/trap.c  |  4 +++-
 port/edf.c | 18 +++++-------------
 3 files changed, 13 insertions(+), 15 deletions(-)

diff --git a/pc/i8253.c b/pc/i8253.c
index c24fd9f3ffd64abf7cce76ecc5eb2e256488201d..8e9102e252778fb20d5a6f505b13c996a8cb689b 100644
--- a/pc/i8253.c
+++ b/pc/i8253.c
@@ -188,6 +188,8 @@ guesscpuhz(int aalcycles)
 ulong i8253periodset;
 int i8253dotimerset = 1;
 
+ulong phist[128];
+
 void
 i8253timerset(uvlong next)
 {
@@ -212,11 +214,13 @@ i8253timerset(uvlong next)
 
 	/* hysteresis */
 	if(i8253.period != period){
+memmove(&phist[0], &phist[1], sizeof(phist)-sizeof(ulong));
+phist[nelem(phist)-1] = period;
 		ilock(&i8253);
 		/* load new value */
 		outb(Tmode, Load0|Square);
 		outb(T0cntr, period);		/* low byte */
-		outb(T0cntr, period>>8);	/* high byte */
+		outb(T0cntr, period>>8);		/* high byte */
 
 		/* remember period */
 		i8253.period = period;
diff --git a/pc/trap.c b/pc/trap.c
index 589ce50e110b9a1ca186fece5b74c5e9824a2789..c78f83e8155f3a8192afebe3f852ec00409d6a3f 100644
--- a/pc/trap.c
+++ b/pc/trap.c
@@ -265,8 +265,10 @@ intrtime(Mach*, int vno)
 		m->perf.inidle -= diff;
 
 	diff /= m->cpumhz;
-	if(diff >= Ntimevec)
+	if(diff >= Ntimevec){
+		if (vno == 32) print("timer took %d µs\n", diff);
 		diff = Ntimevec-1;
+	}
 	intrtimes[vno][diff]++;
 }
 
diff --git a/port/edf.c b/port/edf.c
index ad274c87ad09020b08a0c61b58bc319a167b66cf..1f57f17e063d5cd0290e7518c107b0a1cd6d3c0b 100644
--- a/port/edf.c
+++ b/port/edf.c
@@ -213,8 +213,6 @@ edfreleasetimer(void)
 	if ((t = qwaitrelease.head) == nil)
 		return;
 	DPRINT("edfreleasetimer clock\n");
-	if (releasetimer[m->machno].when)
-		timerdel(&releasetimer[m->machno]);
 	releasetimer[m->machno].when = t->r;
 	if (releasetimer[m->machno].when <= now)
 		releasetimer[m->machno].when = now;
@@ -356,8 +354,6 @@ edfadmit(Task *t)
 		}
 		assert(t->runq.n > 0 || (up && up->task == t));
 		edfpush(t);
-		if (deadlinetimer[m->machno].when)
-			timerdel(&deadlinetimer[m->machno]);
 		deadlinetimer[m->machno].when = t->d;
 		timeradd(&deadlinetimer[m->machno]);
 	}else{
@@ -478,6 +474,8 @@ edfdeadlineintr(Ureg*, Timer *timer)
 		now = fastticks(nil);
 
 		t = up->task;
+
+		assert(t->state == EdfRunning);
 		assert(t->scheduled > 0);
 	
 		used = now - t->scheduled;
@@ -806,12 +804,9 @@ runt:
 		DPRINT("%d edftimer: %T too late\n", m->machno, ticks2time(now-when));
 		when = now;
 	}
-	if (deadlinetimer[m->machno].when){
-		if(deadlinetimer[m->machno].when == when){
-			iunlock(&edflock);
-			return p;
-		}
-		timerdel(&deadlinetimer[m->machno]);
+	if(deadlinetimer[m->machno].when == when){
+		iunlock(&edflock);
+		return p;
 	}
 	deadlinetimer[m->machno].when = when;
 	timeradd(&deadlinetimer[m->machno]);
@@ -1081,7 +1076,6 @@ resacquire(Task *t, CSN *c)
 		t->curcsn->S -= used;
 	when = now + c->S;
 	if (when < deadlinetimer[m->machno].when){
-		timerdel(&deadlinetimer[m->machno]);
 		deadlinetimer[m->machno].when = when;
 		timeradd(&deadlinetimer[m->machno]);
 	}
@@ -1119,8 +1113,6 @@ resrelease(Task *t)
 		t->Delta = Infinity;
 	c->S = 0LL;	/* don't allow reuse */
 	if(devrt) devrt(t, now, SResrel);
-	if (deadlinetimer[m->machno].when)
-		timerdel(&deadlinetimer[m->machno]);
 	deadlinetimer[m->machno].when = when;
 	timeradd(&deadlinetimer[m->machno]);