Author: alc
Date: Mon Aug 2 21:33:36 2010
New Revision: 210782
URL: http://svn.freebsd.org/changeset/base/210782
Log:
Update the "desiredvnodes" calculation. In particular, make the part of
the calculation that is based on the kernel's heap size more conservative.
Hopefully, this will eliminate the need for MAXVNODES_MAX, but for the
time being set MAXVNODES_MAX to a large value.
Reviewed by: jhb@
MFC after: 6 weeks
Modified:
head/sys/kern/vfs_subr.c
Modified: head/sys/kern/vfs_subr.c
==============================================================================
--- head/sys/kern/vfs_subr.c Mon Aug 2 19:56:07 2010 (r210781)
+++ head/sys/kern/vfs_subr.c Mon Aug 2 21:33:36 2010 (r210782)
@@ -282,23 +282,34 @@ SYSCTL_INT(_debug, OID_AUTO, vnlru_nowhe
/*
* Initialize the vnode management data structures.
+ *
+ * Reevaluate the following cap on the number of vnodes after the physical
+ * memory size exceeds 512GB. In the limit, as the physical memory size
+ * grows, the ratio of physical pages to vnodes approaches sixteen to one.
*/
#ifndef MAXVNODES_MAX
-#define MAXVNODES_MAX 100000
+#define MAXVNODES_MAX (512 * (1024 * 1024 * 1024 / PAGE_SIZE / 16))
#endif
static void
vntblinit(void *dummy __unused)
{
+ int physvnodes, virtvnodes;
/*
- * Desiredvnodes is a function of the physical memory size and
- * the kernel's heap size. Specifically, desiredvnodes scales
- * in proportion to the physical memory size until two fifths
- * of the kernel's heap size is consumed by vnodes and vm
- * objects.
- */
- desiredvnodes = min(maxproc + cnt.v_page_count / 4, 2 * vm_kmem_size /
- (5 * (sizeof(struct vm_object) + sizeof(struct vnode))));
+ * Desiredvnodes is a function of the physical memory size and the
+ * kernel's heap size. Generally speaking, it scales with the
+ * physical memory size. The ratio of desiredvnodes to physical pages
+ * is one to four until desiredvnodes exceeds 98,304. Thereafter, the
+ * marginal ratio of desiredvnodes to physical pages is one to
+ * sixteen. However, desiredvnodes is limited by the kernel's heap
+ * size. The memory required by desiredvnodes vnodes and vm objects
+ * may not exceed one seventh of the kernel's heap size.
+ */
+ physvnodes = maxproc + cnt.v_page_count / 16 + 3 * min(98304 * 4,
+ cnt.v_page_count) / 16;
+ virtvnodes = vm_kmem_size / (7 * (sizeof(struct vm_object) +
+ sizeof(struct vnode)));
+ desiredvnodes = min(physvnodes, virtvnodes);
if (desiredvnodes > MAXVNODES_MAX) {
if (bootverbose)
printf("Reducing kern.maxvnodes %d -> %d\n",
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