From 641ff7e9cb265146b27ce6f71faa4d2ae39d0309 Mon Sep 17 00:00:00 2001
From: David du Colombier <0intro@gmail.com>
Date: Tue, 17 Aug 1993 00:00:00 +0000
Subject: [PATCH] Plan 9 from Bell Labs 1993-08-17

---
 port/page.c    | 84 ++++++++++++++++++++++++++++++++++++++------------
 port/portdat.h |  4 ++-
 port/portfns.h |  1 -
 3 files changed, 68 insertions(+), 21 deletions(-)

diff --git a/port/page.c b/port/page.c
index aa28157b754d6272fb317a2f828e22dddfea6859..46cbc4d4f84b55d9e73467900067d152026c8609 100644
--- a/port/page.c
+++ b/port/page.c
@@ -13,19 +13,24 @@ struct	Palloc palloc;
 void
 pageinit(void)
 {
+	int color;
 	Page *p;
-	ulong np, vmem, pmem;
+	ulong np, vm, pm;
 
 	np = palloc.np0+palloc.np1;
 	palloc.head = xalloc(np*sizeof(Page));
 	if(palloc.head == 0)
 		panic("pageinit");
 
+	color = 0;
 	p = palloc.head;
 	while(palloc.np0 > 0) {
 		p->prev = p-1;
 		p->next = p+1;
 		p->pa = palloc.p0;
+		p->color = color;
+		palloc.freecol[color]++;
+		color = (color+1)%NCOLOR;
 		palloc.p0 += BY2PG;
 		palloc.np0--;
 		p++;
@@ -34,6 +39,9 @@ pageinit(void)
 		p->prev = p-1;
 		p->next = p+1;
 		p->pa = palloc.p1;
+		p->color = color;
+		palloc.freecol[color]++;
+		color = (color+1)%NCOLOR;
 		palloc.p1 += BY2PG;
 		palloc.np1--;
 		p++;
@@ -43,15 +51,14 @@ pageinit(void)
 	palloc.tail->next = 0;
 
 	palloc.user = p - palloc.head;
-	palloc.freecount = palloc.user;
-	pmem = palloc.user*BY2PG/1024;
-	vmem = pmem + (conf.nswap*BY2PG)/1024;
+	pm = palloc.user*BY2PG/1024;
+	vm = pm + (conf.nswap*BY2PG)/1024;
 
 	/* Pageing numbers */
-	swapalloc.highwater = (palloc.freecount*5)/100;
+	swapalloc.highwater = (palloc.user*5)/100;
 	swapalloc.headroom = swapalloc.highwater + (swapalloc.highwater/4);
 
-	print("%lud free pages\n%dK bytes\n%dK swap\n", palloc.user, pmem, vmem);
+	print("%lud free pages\n%dK bytes\n%dK swap\n", palloc.user, pm, vm);
 }
 
 Page*
@@ -59,14 +66,19 @@ newpage(int clear, Segment **s, ulong va)
 {
 	Page *p;
 	KMap *k;
-	int i, hw, dontalloc, fc;
+	int i, hw, dontalloc, color;
 
 retry:
 	lock(&palloc);
 
+	color = getcolor(va);
 	hw = swapalloc.highwater;
-	fc = palloc.freecount;
-	while((fc < hw && up->kp == 0) || fc == 0) {
+	for(;;) {
+		if(palloc.freecol[color] > hw)
+			break;
+		if(up->kp && palloc.freecol[color] > 0)
+			break;
+
 		palloc.wanted++;
 		unlock(&palloc);
 		dontalloc = 0;
@@ -75,7 +87,7 @@ retry:
 			*s = 0;
 			dontalloc = 1;
 		}
-		qlock(&palloc.pwait);	/* Hold memory requesters here */
+		qlock(&palloc.pwait);	 /* Hold memory requesters here */
 
 		while(waserror())	/* Ignore interrupts */
 			;
@@ -100,13 +112,26 @@ retry:
 		palloc.wanted--;
 	}
 
-	p = palloc.head;
-	if(palloc.head = p->next)		/* = Assign */
-		palloc.head->prev = 0;
+	for(p = palloc.head; p; p = p->next)
+		if(p->color == color)
+			break;
+
+	if(p == 0)
+		panic("newpage");
+
+	if(p->prev) 
+		p->prev->next = p->next;
 	else
-		palloc.tail = 0;
+		palloc.head = p->next;
+
+	if(p->next)
+		p->next->prev = p->prev;
+	else
+		palloc.tail = p->prev;
+
 
 	palloc.freecount--;
+	palloc.freecol[color]--;
 	unlock(&palloc);
 
 	lock(p);
@@ -158,7 +183,6 @@ putpage(Page *p)
 		return;
 	}
 
-	vcacheinval(p, p->va);
 	lock(&palloc);
 	if(p->image && p->image != &swapimage) {
 		if(palloc.tail) {
@@ -186,6 +210,10 @@ putpage(Page *p)
 	}
 
 	palloc.freecount++;	/* Release people waiting for memory */
+	palloc.freecol[p->color]++;
+	if(palloc.r.p != 0)
+		wakeup(&palloc.r);
+
 	unlock(&palloc);
 	unlock(p);
 }
@@ -194,6 +222,7 @@ void
 duppage(Page *p)				/* Always call with p locked */
 {
 	Page *np;
+	int color;
 
 	/* No dup for swap pages */
 	if(p->image == &swapimage) {
@@ -209,11 +238,27 @@ duppage(Page *p)				/* Always call with p locked */
 		return;
 	}
 
-	np = palloc.head;		/* Allocate a new page from freelist */
-	if(palloc.head = np->next)	/* = Assign */
-		palloc.head->prev = 0;
+	color = getcolor(p->va);
+	for(np = palloc.head; np; np = np->next)
+		if(np->color == color)
+			break;
+
+	/* No page of the correct color */
+	if(np == 0) {
+		unlock(&palloc);
+		uncachepage(p);	
+		return;
+	}
+
+	if(np->prev) 
+		np->prev->next = np->next;
+	else
+		palloc.head = np->next;
+
+	if(np->next)
+		np->next->prev = np->prev;
 	else
-		palloc.tail = 0;
+		palloc.tail = np->prev;
 
 	if(palloc.tail) {		/* Link back onto tail to give us lru */
 		np->prev = palloc.tail;
@@ -349,6 +394,7 @@ lookpage(Image *i, ulong daddr)
 				else
 					palloc.tail = f->prev;
 				palloc.freecount--;
+				palloc.freecol[f->color]--;
 			}
 			unlock(&palloc);
 
diff --git a/port/portdat.h b/port/portdat.h
index 42ea48a8fd5c31c5b9110772f33fd6d54ae1330b..5871449de05d4a1dd9fd859df8ddc957a0f1675e 100644
--- a/port/portdat.h
+++ b/port/portdat.h
@@ -306,6 +306,7 @@ struct Page
 	ulong	daddr;			/* Disc address on swap */
 	ushort	ref;			/* Reference count */
 	char	modref;			/* Simulated modify/reference bits */
+	char	color;			/* Cache coloring */
 	char	cachectl[MAXMACH];	/* Cache flushing control for putmmu */
 	Image	*image;			/* Associated text or swap image */
 	Page	*next;			/* Lru free list */
@@ -454,7 +455,8 @@ struct Palloc
 	ulong	np0, np1;		/* number of pages in bank 0/1 */
 	Page	*head;			/* most recently used */
 	Page	*tail;			/* least recently used */
-	ulong	freecount;		/* how many pages on free list now */
+	ulong	freecount;
+	ulong	freecol[NCOLOR];	/* how many pages on free list now */
 	ulong	user;			/* how many user pages */
 	Page	*hash[PGHSIZE];
 	Lock	hashlock;
diff --git a/port/portfns.h b/port/portfns.h
index ee7e4de57502fcf442807c10ed2dacc4c18f82ca..0f07d8d301e286eb815adf3e0a06c1dc6dcc41d7 100644
--- a/port/portfns.h
+++ b/port/portfns.h
@@ -81,7 +81,6 @@ void		freechan(Chan*);
 void		freepte(Segment*, Pte*);
 void		freesegs(int);
 void		freesession(Session*);
-void		getcolor(ulong, ulong*, ulong*, ulong*);
 int		getfields(char*, char**, int, char);
 void		gotolabel(Label*);
 int		haswaitq(void*);