diff --git a/usr/rsc/mem/Makefile b/usr/rsc/mem/Makefile
index 8f2eace2483..0bfb89b512b 100644
--- a/usr/rsc/mem/Makefile
+++ b/usr/rsc/mem/Makefile
@@ -31,3 +31,7 @@ test%: test%.$O $(OFILES)
 
 clean:
 	rm -f *.$O $(TARG)
+
+runtime: allocator.$O malloc.$O pagemap.$O triv.$O stack.$O
+	6ar grc $(GOROOT)/lib/lib_$(GOARCH)_$(GOOS).a $^
+
diff --git a/usr/rsc/mem/allocator.go b/usr/rsc/mem/allocator.go
index da624fcd5c5..a0d95e77c81 100644
--- a/usr/rsc/mem/allocator.go
+++ b/usr/rsc/mem/allocator.go
@@ -10,3 +10,4 @@ export func memset(*byte, int, int)
 export var footprint int64
 export var frozen bool
 export func testsizetoclass()
+export var allocated int64
diff --git a/usr/rsc/mem/malloc.c b/usr/rsc/mem/malloc.c
index f5461cddf71..02fe40bd3dd 100644
--- a/usr/rsc/mem/malloc.c
+++ b/usr/rsc/mem/malloc.c
@@ -107,13 +107,7 @@ allocspan(int32 npage)
 		if(s->length >= npage) {
 			*l = s->next;
 			s->next = nil;
-if(s->length > npage) {
-prints("Chop span");
-sys·printint(s->length);
-prints(" for ");
-sys·printint(npage);
-prints("\n");
-}
+//if(s->length > npage) printf("Chop span %D for %d\n", s->length, npage);
 			goto havespan;
 		}
 	}
@@ -125,11 +119,7 @@ prints("\n");
 	if(allocnpage < (1<<20>>PageShift))	// TODO: Tune
 		allocnpage = (1<<20>>PageShift);
 	s->length = allocnpage;
-prints("New span ");
-sys·printint(allocnpage);
-prints(" for ");
-sys·printint(npage);
-prints("\n");
+//printf("New span %d for %d\n", allocnpage, npage);
 	s->base = trivalloc(allocnpage<<PageShift);
 	insertspan(s);
 
@@ -237,21 +227,13 @@ allocator·testsizetoclass(void)
 	for(i=0; i<nelem(classtosize); i++) {
 		for(; n <= classtosize[i]; n++) {
 			if(sizetoclass(n) != i) {
-				prints("sizetoclass ");
-				sys·printint(n);
-				prints(" = ");
-				sys·printint(sizetoclass(n));
-				prints(" want ");
-				sys·printint(i);
-				prints("\n");
+				printf("sizetoclass %d = %d want %d\n", n, sizetoclass(n), i);
 				throw("testsizetoclass");
 			}
 		}
 	}
 	if (n != 32768+1) {
-		prints("testsizetoclass stopped at ");
-		sys·printint(n);
-		prints("\n");
+		printf("testsizetoclass stopped at %d\n", n);
 		throw("testsizetoclass");
 	}
 }
@@ -274,20 +256,19 @@ centralgrab(int32 cl, int32 *pn)
 	}
 	chunk = (chunk+PageMask) & ~PageMask;
 	s = allocspan(chunk>>PageShift);
-prints("New Class ");
-sys·printint(cl);
-prints("\n");
+//printf("New class %d\n", cl);
 	s->state = SpanInUse;
 	s->cl = cl;
 	siz = classtosize[cl];
 	n = chunk/siz;
 	p = s->base;
+//printf("centralgrab cl=%d siz=%d n=%d\n", cl, siz, n);
 	for(i=0; i<n-1; i++) {
 		*(void**)p = p+siz;
 		p += siz;
 	}
 	*pn = n;
-	return p;
+	return s->base;
 }
 
 // Allocate a small object of size class cl.
@@ -305,11 +286,13 @@ allocsmall(int32 cl)
 	if(p == nil) {
 		// otherwise grab some blocks from central cache.
 		lock(&central);
+//printf("centralgrab for %d\n", cl);
 		p = centralgrab(cl, &n);
 		// TODO: update local counters using n
 		unlock(&central);
 	}
 
+//printf("alloc from cl %d\n", cl);
 	// advance linked list.
 	m->freelist[cl] = *p;
 
@@ -327,9 +310,7 @@ alloclarge(int32 np)
 	Span *s;
 
 	lock(&central);
-//prints("Alloc span ");
-//sys·printint(np);
-//prints("\n");
+//printf("Alloc span %d\n", np);
 	s = allocspan(np);
 	unlock(&central);
 	s->state = SpanInUse;
@@ -346,17 +327,16 @@ alloc(int32 n)
 	if(n < LargeSize) {
 		cl = sizetoclass(n);
 		if(cl < 0 || cl >= SmallFreeClasses) {
-			sys·printint(n);
-			prints(" -> ");
-			sys·printint(cl);
-			prints("\n");
+			printf("%d -> %d\n", n, cl);
 			throw("alloc - logic error");
 		}
-		return allocsmall(sizetoclass(n));
+		allocator·allocated += classtosize[cl];
+		return allocsmall(cl);
 	}
 
 	// count number of pages; careful about overflow for big n.
 	np = (n>>PageShift) + (((n&PageMask)+PageMask)>>PageShift);
+	allocator·allocated += (uint64)np<<PageShift;
 	return alloclarge(np);
 }
 
@@ -386,9 +366,8 @@ free(void *v)
 		// TODO: For large spans, maybe just return the
 		// memory to the operating system and let it zero it.
 		sys·memclr(s->base, s->length << PageShift);
-//prints("Free big ");
-//sys·printint(s->length);
-//prints("\n");
+//printf("Free big %D\n", s->length);
+		allocator·allocated -= s->length << PageShift;
 		lock(&central);
 		freespan(s);
 		unlock(&central);
@@ -403,9 +382,11 @@ free(void *v)
 
 	// Zero and add to free list.
 	sys·memclr(v, siz);
+	allocator·allocated -= siz;
 	p = v;
 	*p = m->freelist[s->cl];
 	m->freelist[s->cl] = p;
+//printf("Free siz %d cl %d\n", siz, s->cl);
 }
 
 void
@@ -423,21 +404,3 @@ allocator·memset(byte *v, int32 c, int32 n)
 		v[i] = c;
 }
 
-// Allocate stack segment.
-// Must be done without holding locks, because
-// calling any function might trigger another stack segment allocation.
-void*
-allocstack(int32 n)
-{
-	// TODO
-	USED(n);
-	return nil;
-}
-
-void
-freestack(void *v)
-{
-	// TODO
-	USED(v);
-}
-
diff --git a/usr/rsc/mem/malloc.h b/usr/rsc/mem/malloc.h
index aa3bed2c6b3..dd51e49b24d 100644
--- a/usr/rsc/mem/malloc.h
+++ b/usr/rsc/mem/malloc.h
@@ -24,9 +24,13 @@ struct PageMap
 	void *level0[PMLevelSize];
 };
 
+extern int64 allocator·allocated;
 extern int64 allocator·footprint;
 extern bool allocator·frozen;
 
 void* trivalloc(int32);
 void* pmlookup(PageMap*, uintptr);
 void* pminsert(PageMap*, uintptr, void*);
+
+void*	alloc(int32);
+void	free(void*);
diff --git a/usr/rsc/mem/stack.c b/usr/rsc/mem/stack.c
new file mode 100644
index 00000000000..295e709ffb2
--- /dev/null
+++ b/usr/rsc/mem/stack.c
@@ -0,0 +1,22 @@
+// Copyright 2009 The Go Authors.  All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+#include "malloc.h"
+
+void*
+stackalloc(uint32 n)
+{
+	void *v;
+
+	v = alloc(n);
+//printf("stackalloc %d = %p\n", n, v);
+	return v;
+}
+
+void
+stackfree(void *v)
+{
+//printf("stackfree %p\n", v);
+	free(v);
+}
diff --git a/usr/rsc/mem/triv.c b/usr/rsc/mem/triv.c
index 631e93a0940..935cb9fc081 100644
--- a/usr/rsc/mem/triv.c
+++ b/usr/rsc/mem/triv.c
@@ -36,6 +36,7 @@ trivalloc(int32 size)
 	static byte *p;
 	static int32 n;
 	byte *v;
+	uint64 oldfoot;
 
 	if(allocator·frozen)
 		throw("allocator frozen");
@@ -44,6 +45,7 @@ trivalloc(int32 size)
 //sys·printint(size);
 //prints("\n");
 
+	oldfoot = allocator·footprint;
 	if(size < 4096) {	// TODO: Tune constant.
 		size = (size + Round) & ~Round;
 		if(size > n) {
@@ -53,12 +55,20 @@ trivalloc(int32 size)
 		}
 		v = p;
 		p += size;
-		return v;
+		goto out;
 	}
 	if(size & PageMask)
 		size += (1<<PageShift) - (size & PageMask);
 	v = sys·mmap(nil, size, PROT_READ|PROT_WRITE, MAP_ANON|MAP_PRIVATE, 0, 0);
 	allocator·footprint += size;
+
+out:
+	if((oldfoot>>24) != (allocator·footprint>>24))
+		printf("memory footprint = %D MB for %D MB\n", allocator·footprint>>20, allocator·allocated>>20);
+	if(allocator·footprint >= 2LL<<30) {
+		prints("out of memory\n");
+		sys·exit(1);
+	}
 	return v;
 }