VMSTAT(8) VMSTAT(8)
NAME
vmstat - report virtual memory statistics
SYNOPSIS
vmstat [ -fHilms ] [ -h histname ] [ -c count ] [ -M core ] [ -N system ] [ -w wait ] [ disks ]
DESCRIPTION
Vmstat reports certain kernel statistics kept about pro- cess, virtual memory, disk, trap and cpu activity. The options are as follows: -c 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 dis- play. If no wait interval is specified, the default is 1 second. -f Report fork statistics. -i Report on the number of interrupts taken by each device since system startup. -M Extract values associated with the name list from the specified core instead of the default ``/dev/mem''. -N Extract the name list from the specified system instead of the default ``/netbsd''. -m Report on the usage of kernel dynamic memory listed first by size of allocation and then by type of usage. -s Display the contents of the sum structure, giving the total number of several kinds of paging related events which have occurred since system startup. -w Pause wait seconds between each display. If no repeat count is specified, the default is infinity. The following options only apply if vmstat was built with support for UVM: -l List the UVM histories being maintained by the ker- nel. -h Dump the specified UVM history. -H Dump all UVM histories. By default, vmstat displays the following information: February 12, 1998 1 VMSTAT(8) VMSTAT(8) procs Information about the numbers of processes in vari- ous states. r in run queue b blocked for resources (i/o, paging, etc.) w runnable or short sleeper (< 20 secs) but swapped 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 pro- cesses 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 each five seconds, and given in units per second. re page reclaims (simulating reference bits) at pages attached (found in free list) pi pages paged in po pages paged out fr pages freed per second de anticipated short term memory shortfall 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 character of the disk name and the unit number. If more than four disk drives are configured in the system, vmstat dis- plays only the first four drives. To force vmstat to display specific drives, their names may be sup- plied 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
EXAMPLES
The command ``vmstat -w 5'' will print what the system is doing every five seconds; this is a good choice of print- ing interval since this is how often some of the February 12, 1998 2 VMSTAT(8) VMSTAT(8) statistics are sampled in the system. Others vary every second and running the output for a while will make it apparent which are recomputed every second.
FILES
/netbsd default kernel namelist /dev/mem default memory file
SEE ALSO
fstat(1), netstat(1), nfsstat(1), ps(1), systat(1), iostat(8), pstat(8) The sections starting with ``Interpreting system activ- ity'' in Installing and Operating 4.3BSD.
BUGS
The -c and -w options are only available with the default output. February 12, 1998 3
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