shithub: riscv

Info  •  Files  •  Log  •  Branches

kernel: get rid of physical page bank array and use conf.mem[] instead

We can take advantage of the fact that xinit() allocates
kernel memory from conf.mem[] banks always at the beginning
of a bank, so the separate palloc.mem[] array can be eleminated
as we can calculate the amount of non-kernel memory like:

upages = cm->npage - (PGROUND(cm->klimit - cm->kbase)/BY2PG)

for the number of reserved kernel pages,
we provide the new function: ulong nkpages(Confmem*)

This eleminates the error case of running out of slots in
the array and avoids wasting memory in ports that have simple
memory configurations (compared to pc/pc64).

--- a/sys/src/9/pc64/mmu.c

+++ b/sys/src/9/pc64/mmu.c

@@ -652,7 +652,7 @@

 void

 preallocpages(void)

 {

-	Pallocmem *pm;

+	Confmem *cm;

 	uintptr va, base, top;

 	vlong tsize, psize;

 	ulong np, nt;

@@ -659,9 +659,9 @@

 	int i;

 	np = 0;

-	for(i=0; i<nelem(palloc.mem); i++){

-		pm = &palloc.mem[i];

-		np += pm->npage;

+	for(i=0; i<nelem(conf.mem); i++){

+		cm = &conf.mem[i];

+		np += cm->npage - nkpages(cm);

 	}

 	nt = np / 50;	/* 2% for mmupool */

 	np -= nt;

@@ -676,16 +676,19 @@

 	psize += tsize;

 	psize = ROUND(psize, PGLSZ(1));

-	for(i=0; i<nelem(palloc.mem); i++){

-		pm = &palloc.mem[i];

-		base = ROUND(pm->base, PGLSZ(1));

-		top = pm->base + (uvlong)pm->npage * BY2PG;

-		if((base + psize) <= VMAPSIZE && (vlong)(top - base) >= psize){

-			pm->base = base + psize;

-			pm->npage = (top - pm->base)/BY2PG;

+	for(i=0; i<nelem(conf.mem); i++){

+		cm = &conf.mem[i];

+		base = cm->base;

+		top = base + (uvlong)cm->npage * BY2PG;

+		base += (uvlong)nkpages(cm) * BY2PG;

+		top &= -PGLSZ(1);

+		if(top <= VMAPSIZE && (vlong)(top - base) >= psize){

+			/* steal memory from the end of the bank */

+			top -= psize;

+			cm->npage = (top - cm->base) / BY2PG;

-			va = base + VMAP;

-			pmap(base | PTEGLOBAL|PTEWRITE|PTENOEXEC|PTEVALID, va, psize);

+			va = top + VMAP;

+			pmap(top | PTEGLOBAL|PTEWRITE|PTENOEXEC|PTEVALID, va, psize);

 			palloc.pages = (void*)(va + tsize);

--- a/sys/src/9/port/page.c

+++ b/sys/src/9/port/page.c

@@ -7,12 +7,18 @@

 Palloc palloc;

+ulong

+nkpages(Confmem *cm)

+{

+	return ((cm->klimit - cm->kbase) + BY2PG-1) / BY2PG;

+}

+

 void

 pageinit(void)

 {

 	int color, i, j;

 	Page *p, **t;

-	Pallocmem *pm;

+	Confmem *cm;

 	vlong m, v, u;

 	if(palloc.pages == nil){

@@ -19,9 +25,9 @@

 		ulong np;

 		np = 0;

-		for(i=0; i<nelem(palloc.mem); i++){

-			pm = &palloc.mem[i];

-			np += pm->npage;

+		for(i=0; i<nelem(conf.mem); i++){

+			cm = &conf.mem[i];

+			np += cm->npage - nkpages(cm);

 		}

 		palloc.pages = xalloc(np*sizeof(Page));

 		if(palloc.pages == nil)

@@ -35,11 +41,11 @@

 	t = &palloc.head;

 	p = palloc.pages;

-	for(i=0; i<nelem(palloc.mem); i++){

-		pm = &palloc.mem[i];

-		for(j=0; j<pm->npage; j++){

+	for(i=0; i<nelem(conf.mem); i++){

+		cm = &conf.mem[i];

+		for(j=nkpages(cm); j<cm->npage; j++){

 			memset(p, 0, sizeof *p);

-			p->pa = pm->base+j*BY2PG;

+			p->pa = cm->base+j*BY2PG;

 			if(cankaddr(p->pa) && (KADDR(p->pa) == nil || KADDR(p->pa) == (void*)-BY2PG))

 				continue;

 			p->color = color;

--- a/sys/src/9/port/portdat.h

+++ b/sys/src/9/port/portdat.h

@@ -25,7 +25,6 @@

 typedef struct Page	Page;

 typedef struct Path	Path;

 typedef struct Palloc	Palloc;

-typedef struct Pallocmem	Pallocmem;

 typedef struct Perf	Perf;

 typedef struct PhysUart	PhysUart;

 typedef struct Pgrp	Pgrp;

@@ -519,12 +518,6 @@

 	DELTAFD	= 20		/* incremental increase in Fgrp.fd's */

 };

-struct Pallocmem

-{

-	uintptr	base;

-	ulong	npage;

-};

-

 struct Palloc

 {

 	Lock;

@@ -533,7 +526,6 @@

 	Page	*pages;			/* array of all pages */

 	ulong	user;			/* how many user pages */

 	Rendezq		pwait[2];	/* Queues of procs waiting for memory */

-	Pallocmem	mem[16];	/* physical user page banks */

 };

 struct Waitq

--- a/sys/src/9/port/portfns.h

+++ b/sys/src/9/port/portfns.h

@@ -213,6 +213,7 @@

 Proc*		newproc(void);

 void		nexterror(void);

 int		notify(Ureg*);

+ulong		nkpages(Confmem*);

 uvlong		ns2fastticks(uvlong);

 int		okaddr(uintptr, ulong, int);

 int		openmode(ulong);

--- a/sys/src/9/port/xalloc.c

+++ b/sys/src/9/port/xalloc.c

@@ -43,10 +43,8 @@

 xinit(void)

 {

 	ulong maxpages, kpages, n;

-	uintptr size;

-	Confmem *m;

-	Pallocmem *pm;

 	Hole *h, *eh;

+	Confmem *cm;

 	int i;

 	eh = &xlists.hole[Nhole-1];

@@ -57,36 +55,28 @@

 	kpages = conf.npage - conf.upages;

-	pm = palloc.mem;

 	for(i=0; i<nelem(conf.mem); i++){

-		m = &conf.mem[i];

-		n = m->npage;

+		cm = &conf.mem[i];

+		n = cm->npage;

 		if(n > kpages)

 			n = kpages;

 		/* don't try to use non-KADDR-able memory for kernel */

-		maxpages = cankaddr(m->base)/BY2PG;

+		maxpages = cankaddr(cm->base)/BY2PG;

 		if(n > maxpages)

 			n = maxpages;

-		size = (uintptr)n*BY2PG;

-		/* first give to kernel */

+		/* give to kernel */

 		if(n > 0){

-			m->kbase = (uintptr)KADDR(m->base);

-			m->klimit = (uintptr)m->kbase+size;

-			if(m->klimit == 0)

-				m->klimit = (uintptr)-BY2PG;

-			xhole(m->base, m->klimit - m->kbase);

+			cm->kbase = (uintptr)KADDR(cm->base);

+			cm->klimit = (uintptr)cm->kbase+(uintptr)n*BY2PG;

+			if(cm->klimit == 0)

+				cm->klimit = (uintptr)-BY2PG;

+			xhole(cm->base, cm->klimit - cm->kbase);

 			kpages -= n;

 		}

-		/* if anything left over, give to user */

-		if(n < m->npage){

-			if(pm >= palloc.mem+nelem(palloc.mem)){

-				print("xinit: losing %lud pages\n", m->npage-n);

-				continue;

-			}

-			pm->base = m->base+size;

-			pm->npage = m->npage - n;

-			pm++;

-		}

+		/*

+		 * anything left over: cm->npage - nkpages(cm)

+		 * will be given to user by pageinit()

+		 */

 	}

 	xsummary();

 }