From 04b78032914d58a33745a1a13e2e3de99a7d94b4 Mon Sep 17 00:00:00 2001
From: cinap_lenrek <cinap_lenrek@gmx.de>
Date: Sat, 22 Jun 2013 09:50:34 +0200
Subject: apic: eleminate splhi and apictimerlock, per cpu apictimer structure

the splhi() and apictimerlock in the Mach isnt neccesary, as
portclock always holds the ilock of the per mach timer queue
when calling timerset().

as fastticks() and the portclock timers are all handled on a
per processor basis, i think it should be theoretically possible
for the lapics to run at different frequencies. so we measure
the lapic frequency for each individual lapic and keep them in
a per processor Apictimer structure instead of assuming them
to be the same.
---
 sys/src/9/pc/apic.c | 96 +++++++++++++++++++++++++++++------------------------
 sys/src/9/pc/dat.h  |  1 -
 2 files changed, 53 insertions(+), 44 deletions(-)

diff --git a/sys/src/9/pc/apic.c b/sys/src/9/pc/apic.c
index 4e006e8fb..f27adb81e 100644
--- a/sys/src/9/pc/apic.c
+++ b/sys/src/9/pc/apic.c
@@ -89,14 +89,17 @@ static uchar lapictdxtab[] = {		/* LapicTDCR */
 
 static ulong* lapicbase;
 
-struct
+typedef struct Apictimer Apictimer;
+struct Apictimer
 {
 	uvlong	hz;
 	ulong	max;
 	ulong	min;
 	ulong	div;
 	int	tdx;
-} lapictimer;
+};
+
+static Apictimer lapictimer[MAXMACH];
 
 static ulong
 lapicr(int r)
@@ -115,20 +118,24 @@ lapicw(int r, ulong data)
 void
 lapiconline(void)
 {
+	Apictimer *a;
+
+	a = &lapictimer[m->machno];
+
 	/*
 	 * Reload the timer to de-synchronise the processors,
 	 * then lower the task priority to allow interrupts to be
 	 * accepted by the APIC.
 	 */
 	microdelay((TK2MS(1)*1000/conf.nmach) * m->machno);
-	lapicw(LapicTICR, lapictimer.max);
+	lapicw(LapicTICR, a->max);
 	lapicw(LapicTIMER, LapicCLKIN|LapicPERIODIC|(VectorPIC+IrqTIMER));
 
 	/*
 	 * not strickly neccesary, but reported (osdev.org) to be
 	 * required for some machines.
 	 */
-	lapicw(LapicTDCR, lapictdxtab[lapictimer.tdx]);
+	lapicw(LapicTDCR, lapictdxtab[a->tdx]);
 
 	lapicw(LapicTPR, 0);
 }
@@ -139,35 +146,44 @@ lapiconline(void)
 static void
 lapictimerinit(void)
 {
+	uvlong x, v, hz;
+	Apictimer *a;
+	int s;
+
+	s = splhi();
+	a = &lapictimer[m->machno];
+	a->tdx = 0;
 Retry:
 	lapicw(LapicTIMER, ApicIMASK|LapicCLKIN|LapicONESHOT|(VectorPIC+IrqTIMER));
-	lapicw(LapicTDCR, lapictdxtab[lapictimer.tdx]);
-
-	if(lapictimer.hz == 0ULL){
-		uvlong x, v, hz;
-
-		x = fastticks(&hz);
-		x += hz/10;
-		lapicw(LapicTICR, 0xffffffff);
-		do{
-			v = fastticks(nil);
-		}while(v < x);
-
-		v = (0xffffffffUL-lapicr(LapicTCCR))*10;
-		if(v > hz-(hz/10)){
-			if(v > hz+(hz/10) && lapictimer.tdx < nelem(lapictdxtab)-1){
-				lapictimer.tdx++;
-				goto Retry;
-			}
-			v = hz;
+	lapicw(LapicTDCR, lapictdxtab[a->tdx]);
+
+	x = fastticks(&hz);
+	x += hz/10;
+	lapicw(LapicTICR, 0xffffffff);
+	do{
+		v = fastticks(nil);
+	}while(v < x);
+
+	v = (0xffffffffUL-lapicr(LapicTCCR))*10;
+	if(v > hz-(hz/10)){
+		if(v > hz+(hz/10) && a->tdx < nelem(lapictdxtab)-1){
+			a->tdx++;
+			goto Retry;
 		}
-		assert(v != 0);
-
-		lapictimer.hz = v;
-		lapictimer.div = hz/lapictimer.hz;
-		lapictimer.max = lapictimer.hz/HZ;
-		lapictimer.min = lapictimer.hz/(100*HZ);
+		v = hz;
 	}
+
+	assert(v >= (100*HZ));
+
+	a->hz = v;
+	a->div = hz/a->hz;
+	a->max = a->hz/HZ;
+	a->min = a->hz/(100*HZ);
+
+	splx(s);
+
+	v = (v+500000LL)/1000000LL;
+	print("cpu%d: lapic clock at %lludMHz\n", m->machno, v);
 }
 
 void
@@ -377,25 +393,19 @@ void
 lapictimerset(uvlong next)
 {
 	vlong period;
-	int x;
+	Apictimer *a;
 
-	x = splhi();
-	lock(&m->apictimerlock);
-
-	period = lapictimer.max;
+	a = &lapictimer[m->machno];
+	period = a->max;
 	if(next != 0){
 		period = next - fastticks(nil);
-		period /= lapictimer.div;
-
-		if(period < lapictimer.min)
-			period = lapictimer.min;
-		else if(period > lapictimer.max - lapictimer.min)
-			period = lapictimer.max;
+		period /= a->div;
+		if(period < a->min)
+			period = a->min;
+		else if(period > a->max - a->min)
+			period = a->max;
 	}
 	lapicw(LapicTICR, period);
-
-	unlock(&m->apictimerlock);
-	splx(x);
 }
 
 void
diff --git a/sys/src/9/pc/dat.h b/sys/src/9/pc/dat.h
index 862dc344a..8ba2d018e 100644
--- a/sys/src/9/pc/dat.h
+++ b/sys/src/9/pc/dat.h
@@ -242,7 +242,6 @@ struct Mach
 
 	int	loopconst;
 
-	Lock	apictimerlock;
 	int	cpumhz;
 	uvlong	cyclefreq;		/* Frequency of user readable cycle counter */
 	uvlong	cpuhz;
-- 
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