From 6288cbca766267e7a4a44cac6180151d6bed0c38 Mon Sep 17 00:00:00 2001
From: Bob Beck <beck@cvs.openbsd.org>
Date: Wed, 11 Aug 2010 14:35:35 +0000
Subject: Make the number of vnodes to correspond to the number of buffers in
 buffer cache - we grow them dynamically, but do not attempt to shrink them if
 the buffer cache shrinks after growing.

Tested by very many for a long time.

ok oga@ todd@ phessler@ tedu@
---
 sys/kern/vfs_subr.c | 19 ++++++++++++++-----
 1 file changed, 14 insertions(+), 5 deletions(-)

diff --git a/sys/kern/vfs_subr.c b/sys/kern/vfs_subr.c
index 61fc62d20b4..588e255d328 100644
--- a/sys/kern/vfs_subr.c
+++ b/sys/kern/vfs_subr.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: vfs_subr.c,v 1.187 2010/06/29 04:09:32 tedu Exp $	*/
+/*	$OpenBSD: vfs_subr.c,v 1.188 2010/08/11 14:35:34 beck Exp $	*/
 /*	$NetBSD: vfs_subr.c,v 1.53 1996/04/22 01:39:13 christos Exp $	*/
 
 /*
@@ -108,8 +108,10 @@ void vfs_free_addrlist(struct netexport *);
 void vputonfreelist(struct vnode *);
 
 int vflush_vnode(struct vnode *, void *);
+extern struct bcachestats bcasts;
 int maxvnodes;
 
+
 #ifdef DEBUG
 void printlockedvnodes(void);
 #endif
@@ -136,7 +138,7 @@ void
 vntblinit(void)
 {
 	/* buffer cache may need a vnode for each buffer */
-	maxvnodes = desiredvnodes;
+	maxvnodes = 2 * desiredvnodes;
 	pool_init(&vnode_pool, sizeof(struct vnode), 0, 0, 0, "vnodes",
 	    &pool_allocator_nointr);
 	TAILQ_INIT(&vnode_hold_list);
@@ -317,6 +319,13 @@ getnewvnode(enum vtagtype tag, struct mount *mp, int (**vops)(void *),
 	struct vnode *vp;
 	int s;
 
+	/*
+	 * allow maxvnodes to increase if the buffer cache itself
+	 * is big enough to justify it. (we don't shrink it ever)
+	 */
+	maxvnodes = maxvnodes < bcstats.numbufs ? bcstats.numbufs
+	    : maxvnodes;
+
 	/*
 	 * We must choose whether to allocate a new vnode or recycle an
 	 * existing one. The criterion for allocating a new one is that
@@ -333,7 +342,7 @@ getnewvnode(enum vtagtype tag, struct mount *mp, int (**vops)(void *),
 	 * referencing buffers.
 	 */
 	toggle ^= 1;
-	if (numvnodes > 2 * maxvnodes)
+	if (numvnodes / 2 > maxvnodes)
 		toggle = 0;
 
 	s = splbio();
@@ -757,7 +766,7 @@ vdrop(struct vnode *vp)
 {
 #ifdef DIAGNOSTIC
 	if (vp->v_holdcnt == 0)
-		panic("vdrop: zero holdcnt"); 
+		panic("vdrop: zero holdcnt");
 #endif
 
 	vp->v_holdcnt--;
@@ -843,7 +852,7 @@ vflush_vnode(struct vnode *vp, void *arg) {
 		vgonel(vp, p);
 		return (0);
 	}
-		
+
 	/*
 	 * If FORCECLOSE is set, forcibly close the vnode.
 	 * For block or character devices, revert to an
-- 
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