As of r257209, all architectures have defined VM_KMEM_SIZE_SCALE. In other

words, every architecture is now auto-sizing the kmem arena.  This revision
changes kmeminit() so that the definition of VM_KMEM_SIZE_SCALE becomes
mandatory and the definition of VM_KMEM_SIZE becomes optional.

Replace or eliminate all existing definitions of VM_KMEM_SIZE.  With
auto-sizing enabled, VM_KMEM_SIZE effectively became an alternate spelling
for VM_KMEM_SIZE_MIN on most architectures.  Use VM_KMEM_SIZE_MIN for
clarity.

Change kmeminit() so that the effect of defining VM_KMEM_SIZE is similar to
that of setting the tunable vm.kmem_size.  Whereas the macros
VM_KMEM_SIZE_{MAX,MIN,SCALE} have had the same effect as the tunables
vm.kmem_size_{max,min,scale}, the effects of VM_KMEM_SIZE and vm.kmem_size
have been distinct.  In particular, whereas VM_KMEM_SIZE was overridden by
VM_KMEM_SIZE_{MAX,MIN,SCALE} and vm.kmem_size_{max,min,scale}, vm.kmem_size
was not.  Remedy this inconsistency.  Now, VM_KMEM_SIZE can be used to set
the size of the kmem arena at compile-time without that value being
overridden by auto-sizing.

Update the nearby comments to reflect the kmem submap being replaced by the
kmem arena.  Stop duplicating the auto-sizing formula in every machine-
dependent vmparam.h and place it in kmeminit() where auto-sizing takes
place.

Reviewed by:	kib (an earlier version)
Sponsored by:	EMC / Isilon Storage Division

1 files changed, 10 insertions, 11 deletions

diff --git a/sys/i386/include/vmparam.h b/sys/i386/include/vmparam.h
index 19cdd8e..c086d76 100644
--- a/sys/i386/include/vmparam.h
+++ b/sys/i386/include/vmparam.h
@@ -164,24 +164,23 @@
 #define VM_MAX_ADDRESS		VADDR(PTDPTDI, PTDPTDI)
 #define VM_MIN_ADDRESS		((vm_offset_t)0)
 
-/* virtual sizes (bytes) for various kernel submaps */
-#ifndef VM_KMEM_SIZE
-#define VM_KMEM_SIZE		(12 * 1024 * 1024)
-#endif
-
 /*
- * How many physical pages per KVA page allocated.
- * min(max(max(VM_KMEM_SIZE, Physical memory/VM_KMEM_SIZE_SCALE),
- *     VM_KMEM_SIZE_MIN), VM_KMEM_SIZE_MAX)
- * is the total KVA space allocated for kmem_map.
+ * How many physical pages per kmem arena virtual page.
  */
 #ifndef VM_KMEM_SIZE_SCALE
 #define	VM_KMEM_SIZE_SCALE	(3)
 #endif
 
 /*
- * Ceiling on the amount of kmem_map KVA space: 40% of the entire KVA space
- * rounded to the nearest multiple of the superpage size.
+ * Optional floor (in bytes) on the size of the kmem arena.
+ */
+#ifndef VM_KMEM_SIZE_MIN
+#define	VM_KMEM_SIZE_MIN	(12 * 1024 * 1024)
+#endif
+
+/*
+ * Optional ceiling (in bytes) on the size of the kmem arena: 40% of the
+ * kernel map rounded to the nearest multiple of the superpage size.
  */
 #ifndef VM_KMEM_SIZE_MAX
 #define	VM_KMEM_SIZE_MAX	(((((VM_MAX_KERNEL_ADDRESS - \