make nkmempages dynamic based on memory. okay art@ from netbsd:

date: 2000/02/11 19:22:52;  author: thorpej;
Add some very simple code to auto-size the kmem_map.  We take the
amount of physical memory, divide it by 4, and then allow machine
dependent code to place upper and lower bounds on the size.  Export
the computed value to userspace via the new "vm.nkmempages" sysctl.

NKMEMCLUSTERS is now deprecated and will generate an error if you
attempt to use it.  The new option, should you choose to use it,
is called NKMEMPAGES, and two new options NKMEMPAGES_MIN and
NKMEMPAGES_MAX allow the user to configure the bounds in the kernel
config file.

1 files changed, 72 insertions, 9 deletions

diff --git a/sys/kern/kern_malloc.c b/sys/kern/kern_malloc.c
index c18f8067f51..60409bb69b5 100644
--- a/sys/kern/kern_malloc.c
+++ b/sys/kern/kern_malloc.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: kern_malloc.c,v 1.42 2001/11/28 19:28:14 art Exp $	*/
+/*	$OpenBSD: kern_malloc.c,v 1.43 2001/12/05 01:57:15 provos Exp $	*/
 /*	$NetBSD: kern_malloc.c,v 1.15.4.2 1996/06/13 17:10:56 cgd Exp $	*/
 
 /*
@@ -49,7 +49,31 @@
 static struct vm_map kmem_map_store;
 struct vm_map *kmem_map = NULL;
 
-int nkmempages;
+#ifdef NKMEMCLUSTERS
+#error NKMEMCLUSTERS is obsolete; remove it from your kernel config file and use NKMEMPAGES instead or let the kernel auto-size
+#endif
+
+/*
+ * Default number of pages in kmem_map.  We attempt to calculate this
+ * at run-time, but allow it to be either patched or set in the kernel
+ * config file.
+ */
+#ifndef NKMEMPAGES
+#define	NKMEMPAGES	0
+#endif
+int	nkmempages = NKMEMPAGES;
+
+/*
+ * Defaults for lower- and upper-bounds for the kmem_map page count.
+ * Can be overridden by kernel config options.
+ */
+#ifndef	NKMEMPAGES_MIN
+#define	NKMEMPAGES_MIN	NKMEMPAGES_MIN_DEFAULT
+#endif
+
+#ifndef NKMEMPAGES_MAX
+#define	NKMEMPAGES_MAX	NKMEMPAGES_MAX_DEFAULT
+#endif
 
 struct kmembuckets bucket[MINBUCKET + 16];
 struct kmemstats kmemstats[M_LAST];
@@ -409,6 +433,43 @@ free(addr, type)
 }
 
 /*
+ * Compute the number of pages that kmem_map will map, that is,
+ * the size of the kernel malloc arena.
+ */
+void
+kmeminit_nkmempages()
+{
+	int npages;
+
+	if (nkmempages != 0) {
+		/*
+		 * It's already been set (by us being here before, or
+		 * by patching or kernel config options), bail out now.
+		 */
+		return;
+	}
+
+	/*
+	 * We use the following (simple) formula:
+	 *
+	 *	- Starting point is physical memory / 4.
+	 *
+	 *	- Clamp it down to NKMEMPAGES_MAX.
+	 *
+	 *	- Round it up to NKMEMPAGES_MIN.
+	 */
+	npages = physmem / 4;
+
+	if (npages > NKMEMPAGES_MAX)
+		npages = NKMEMPAGES_MAX;
+
+	if (npages < NKMEMPAGES_MIN)
+		npages = NKMEMPAGES_MIN;
+
+	nkmempages = npages;
+}
+
+/*
  * Initialize the kernel memory allocator
  */
 void
@@ -417,18 +478,22 @@ kmeminit()
 #ifdef KMEMSTATS
 	long indx;
 #endif
-	int npg;
 
 #ifdef DIAGNOSTIC
 	if (sizeof(struct freelist) > (1 << MINBUCKET))
 		panic("kmeminit: minbucket too small/struct freelist too big");
 #endif
 
-	npg = VM_KMEM_SIZE / PAGE_SIZE;
+	/*
+	 * Compute the number of kmem_map pages, if we have not
+	 * done so already.
+	 */
+	kmeminit_nkmempages();
+
 	kmemusage = (struct kmemusage *) uvm_km_zalloc(kernel_map,
-		(vsize_t)(npg * sizeof(struct kmemusage)));
+		(vsize_t)(nkmempages * sizeof(struct kmemusage)));
 	kmem_map = uvm_km_suballoc(kernel_map, (vaddr_t *)&kmembase,
-		(vaddr_t *)&kmemlimit, (vsize_t)(npg * PAGE_SIZE), 
+		(vaddr_t *)&kmemlimit, (vsize_t)(nkmempages * PAGE_SIZE), 
 			VM_MAP_INTRSAFE, FALSE, &kmem_map_store);
 #ifdef KMEMSTATS
 	for (indx = 0; indx < MINBUCKET + 16; indx++) {
@@ -439,13 +504,11 @@ kmeminit()
 		bucket[indx].kb_highwat = 5 * bucket[indx].kb_elmpercl;
 	}
 	for (indx = 0; indx < M_LAST; indx++)
-		kmemstats[indx].ks_limit = npg * PAGE_SIZE * 6 / 10;
+		kmemstats[indx].ks_limit = nkmempages * PAGE_SIZE * 6 / 10;
 #endif
 #ifdef MALLOC_DEBUG
 	debug_malloc_init();
 #endif
-
-	nkmempages = npg;
 }
 
 /*