VMSTAT(1)						    BSD General Commands Manual 						 VMSTAT(1)

NAME

     vmstat -- report virtual memory statistics

SYNOPSIS

     vmstat [-CefHiLlmstUvW] [-c count] [-h hashname] [-M core] [-N system] [-u histname] [-w wait] [disks]

DESCRIPTION

     vmstat reports certain kernel statistics kept about process, virtual memory, disk, trap, and CPU activity.

     The options are as follows:

     -C 	  Report on kernel memory caches.  Combine with the -m option to see information about memory pools that back the caches.

     -c count	  Repeat the display count times.  The first display is for the time since a reboot and each subsequent report is for the time
		  period since the last display.  If no wait interval is specified, the default is 1 second.

     -e 	  Report the values of system event counters.

     -f 	  Report fork statistics.

     -H 	  Report all hash table statistics.

     -h hashname  Report hash table statistics for hashname.

     -i 	  Report the values of system interrupt counters.

     -L 	  List all the hashes supported for -h and -H.

     -l 	  List the UVM histories being maintained by the kernel.

     -M core	  Extract values associated with the name list from the specified core instead of the default /dev/mem.

     -m 	  Report on the usage of kernel dynamic memory listed first by size of allocation and then by type of usage, followed by a list of
		  the kernel memory pools and their usage.

     -N system	  Extract the name list from the specified system instead of the default /netbsd.

     -s 	  Display the contents of the uvmexp structure.  This contains various paging event and memory status counters.

     -t 	  Display the contents of the vmtotal structure.  This includes information about processes and virtual memory.

		  The process part shows the number of processes in the following states:

		  ru   on the run queue
		  dw   in disk I/O wait
		  pw   waiting for paging
		  sl   sleeping

		  The virtual memory section shows:

		  total-v   Total virtual memory
		  active-v  Active virtual memory in use
		  active-r  Active real memory in use
		  vm-sh     Shared virtual memory
		  avm-sh    Active shared virtual memory
		  rm-sh     Shared real memory
		  arm-sh    Active shared real memory
		  free	    Free memory

		  All memory values are shown in number of pages.

     -U 	  Dump all UVM histories.

     -u histname  Dump the specified UVM history.

     -v 	  Print more verbose information.  When used with the -i, -e, or -m options prints out all counters, not just those with non-zero
		  values.

     -W 	  Print more verbose information about kernel memory pools.

     -w wait	  Pause wait seconds between each display.  If no repeat count is specified, the default is infinity.

     By default, vmstat displays the following information:

     procs   Information about the numbers of processes in various states.

	     r	   in run queue
	     b	   blocked for resources (i/o, paging, etc.)

     memory  Information about the usage of virtual and real memory.  Virtual pages (reported in units of 1024 bytes) are considered active if
	     they belong to processes which are running or have run in the last 20 seconds.

	     avm   active virtual pages
	     fre   size of the free list

     page    Information about page faults and paging activity.  These are averaged every five seconds, and given in units per second.

	     flt   total page faults
	     re    page reclaims (simulating reference bits)
	     pi    pages paged in
	     po    pages paged out
	     fr    pages freed per second
	     sr    pages scanned by clock algorithm, per-second

     disks   Disk transfers per second.  Typically paging will be split across the available drives.  The header of the field is the first charac-
	     ter of the disk name and the unit number.	If more than four disk drives are configured in the system, vmstat displays only the first
	     four drives.  To force vmstat to display specific drives, their names may be supplied on the command line.

     faults  Trap/interrupt rate averages per second over last 5 seconds.

	     in    device interrupts per interval (including clock interrupts)
	     sy    system calls per interval
	     cs    CPU context switch rate (switches/interval)

     cpu     Breakdown of percentage usage of CPU time.

	     us    user time for normal and low priority processes
	     sy    system time
	     id    CPU idle

FILES

     /netbsd	 default kernel namelist
     /dev/mem	 default memory file

EXAMPLES

     The command ``vmstat -w 5'' will print what the system is doing every five seconds; this is a good choice of printing interval since this is
     how often some of the statistics are sampled in the system.  Others vary every second and running the output for a while will make it appar-
     ent which are recomputed every second.

SEE ALSO

     fstat(1), netstat(1), nfsstat(1), ps(1), systat(1), iostat(8), pstat(8)

     The sections starting with ``Interpreting system activity'' in Installing and Operating 4.3BSD.

BUGS

     The -c and -w options are only available with the default output.

     The -l, -U, and -u options are useful only if the system was compiled with support for UVM history.

BSD
								 October 22, 2009							       BSD