.\" Copyright (c) 1997, Apple Computer, Inc.  All rights reserved.
.\"
.Dd August 13, 1997
.Dt VM_STAT 1
.Os "Mac OS X"
.Sh NAME
.Nm vm_stat
.Nd show Mach virtual memory statistics
.Sh SYNOPSIS
.Nm vm_stat
.Op Ar interval
.Sh DESCRIPTION
.Nm vm_stat 
displays Mach virtual memory statistics.  If the optional 
.Ar interval 
is specified, then 
.Nm vm_stat 
will display the statistics every 
.Ar interval 
seconds.  In this case, each line of output displays the change in
each statistic (an
.Ar interval 
count of 1 displays the values per second).  However, the first line
of output following each banner displays the system-wide totals for
each statistic.  The following values are displayed:
.Bl -tag -width indent
.It Pages free
the total number of free pages in the system.
.It Pages active
the total number of pages currently in use and pageable.
.It Pages inactive
the total number of pages on the inactive list.
.It Pages wired down
the total number of pages wired down.  That is, pages that cannot be
paged out.
.It Translation faults
the number of times the "vm_fault" routine has been called.
.It Pages copy-on-write
the number of faults that caused a page to be
copied (generally caused by copy-on-write faults).
.It Pages zero filled
the total number of pages that have been zero-filled on demand.
.It Pages reactivated
the total number of pages that have been moved from the inactive list
to the active list (reactivated).
.It Pageins
the number of requests for pages from a pager (such as the inode pager).
.It Pageouts
the number of pages that have been paged out.
.El
.Pp
If 
.Ar interval 
is not specified, then 
.Nm vm_stat 
displays all accumulated statistics along with the page size and the
object cache performance.