Improve the page mapped check algorithm in the powerpc pmap module,

before it was looking through two arrays of 8 and a linked list of
undetermined size, before deciding that a mapping was not valid.
Now it allocates a data structure and caches that data.

This improves both pmap_enter and pmap_remove because both check
to see if a mapping is valid before taking the appropriate actions.

Also in pmap_remove, if the va mapping is found, stop searching for
it in the rest of this array, the alternate array and the linked list.
only one valid mapping of each va is allowed.

This change improved lat_mmap (from lmbench) from 1300 to 720
and fork+exit from 7320 to 2724 microseconds.

1 files changed, 14 insertions, 1 deletions

diff --git a/sys/arch/powerpc/include/pmap.h b/sys/arch/powerpc/include/pmap.h
index ab4053d1a84..3f54e7ad34e 100644
--- a/sys/arch/powerpc/include/pmap.h
+++ b/sys/arch/powerpc/include/pmap.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: pmap.h,v 1.3 1997/01/09 03:03:46 rahnds Exp $	*/
+/*	$OpenBSD: pmap.h,v 1.4 2001/02/22 03:26:23 drahn Exp $	*/
 /*	$NetBSD: pmap.h,v 1.1 1996/09/30 16:34:29 ws Exp $	*/
 
 /*-
@@ -49,12 +49,25 @@ typedef u_int sr_t;
 #define	SR_VSID		0x00ffffff
 
 #ifndef _LOCORE
+/* V->P mapping data */
+typedef int pmapv_t;
+#define VP_SR_SIZE	32
+#define VP_SR_MASK	VP_SR_SIZE-1
+#define VP_SR_POS 	27
+#define VP_IDX1_SIZE	1024
+#define VP_IDX1_MASK	VP_IDX1_SIZE-1
+#define VP_IDX1_POS 	17
+#define VP_IDX2_SIZE	32
+#define VP_IDX2_MASK	VP_IDX2_SIZE-1
+#define VP_IDX2_POS 	12
+
 /*
  * Pmap stuff
  */
 struct pmap {
 	sr_t pm_sr[16];		/* segments used in this pmap */
 	int pm_refs;		/* ref count */
+	pmapv_t *vps[VP_SR_SIZE];	/* virtual to physical table */
 	struct pmap_statistics	pm_stats;	/* pmap statistics */
 };