From 844e14d34c660ae3316c0898ce66c64964f2c540 Mon Sep 17 00:00:00 2001
From: Peter Holm <pho@FreeBSD.org>
Date: Tue, 20 Aug 2013 11:06:56 +0000
Subject: [PATCH] Added sysctl to turn off calls to vmem_check().

Sponsored by:	EMC / Isilon storage division
Discussed with:	 jeff
---
 sys/kern/subr_vmem.c | 12 +++++++++---
 1 file changed, 9 insertions(+), 3 deletions(-)

diff --git a/sys/kern/subr_vmem.c b/sys/kern/subr_vmem.c
index fc431e642798..f3f3eecee93d 100644
--- a/sys/kern/subr_vmem.c
+++ b/sys/kern/subr_vmem.c
@@ -54,6 +54,7 @@ __FBSDID("$FreeBSD$");
 #include <sys/mutex.h>
 #include <sys/smp.h>
 #include <sys/condvar.h>
+#include <sys/sysctl.h>
 #include <sys/taskqueue.h>
 #include <sys/vmem.h>
 
@@ -167,6 +168,9 @@ struct vmem_btag {
 #define	BT_END(bt)	((bt)->bt_start + (bt)->bt_size - 1)
 
 #if defined(DIAGNOSTIC)
+static int enable_vmem_check = 1;
+SYSCTL_INT(_debug, OID_AUTO, vmem_check, CTLFLAG_RW,
+    &enable_vmem_check, 0, "Enable vmem check");
 static void vmem_check(vmem_t *);
 #endif
 
@@ -720,9 +724,11 @@ vmem_periodic(void *unused, int pending)
 	LIST_FOREACH(vm, &vmem_list, vm_alllist) {
 #ifdef DIAGNOSTIC
 		/* Convenient time to verify vmem state. */
-		VMEM_LOCK(vm);
-		vmem_check(vm);
-		VMEM_UNLOCK(vm);
+		if (enable_vmem_check == 1) {
+			VMEM_LOCK(vm);
+			vmem_check(vm);
+			VMEM_UNLOCK(vm);
+		}
 #endif
 		desired = 1 << flsl(vm->vm_nbusytag);
 		desired = MIN(MAX(desired, VMEM_HASHSIZE_MIN),