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@(#)vmstat.8 8.1 (Berkeley) 6/6/93
.Dd June 6, 1996 .Dt VMSTAT 8 .Os BSD 4 .Sh NAME .Nm vmstat .Nd report virtual memory statistics .Sh SYNOPSIS .Nm vmstat .Op Fl fimst .Op Fl c Ar count .Op Fl M core .Op Fl N system .Op Fl w wait .Op Ar disks .Sh DESCRIPTION .Nm Vmstat reports certain kernel statistics kept about process, virtual memory, disk, trap and cpu activity.
p The options are as follows: l -tag -width indent t Fl c Repeat the display .Ar 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 .Ar wait interval is specified, the default is 1 second. t Fl f Report on the number .Xr fork 2 and .Xr vfork 2 system calls since system startup, and the number of pages of virtual memory involved in each. t Fl i Report on the number of interrupts taken by each device since system startup. t Fl M Extract values associated with the name list from the specified .Ar core instead of the default
a /dev/kmem . t Fl N Extract the name list from the specified .Ar system instead of the default
a /kernel . t Fl m Report on the usage of kernel dynamic memory listed first by size of allocation and then by type of usage. t Fl s Display the contents of the .Em sum structure, giving the total number of several kinds of paging related events which have occurred since system startup. t Fl t Report on the number of page in and page reclaims since system startup, and the amount of time required by each. t Fl w Pause .Ar wait seconds between each display. If no repeat .Ar count is specified, the default is infinity. .El
p By default, .Nm vmstat displays the following information:
p l -tag -width indent t procs Information about the numbers of processes in various states.
p l -tag -width indent -compact t r in run queue t b blocked for resources (i/o, paging, etc.) t w runnable or short sleeper (< 20 secs) but swapped .El t 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.
p l -tag -width indent -compact t avm active virtual pages t fre size of the free list .El t page Information about page faults and paging activity. These are averaged each five seconds, and given in units per second.
p l -tag -width indent -compact t re page reclaims (simulating reference bits) t at pages attached (found in free list) t pi pages paged in t po pages paged out t fr pages freed per second t de anticipated short term memory shortfall t sr pages scanned by clock algorithm, per-second .El t disks Disk operations per second (this field is system dependent). 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, .Nm vmstat displays only the first four drives. To force .Nm vmstat to display specific drives, their names may be supplied on the command line. t faults Trap/interrupt rate averages per second over last 5 seconds.
p l -tag -width indent -compact t in device interrupts per interval (including clock interrupts) t sy system calls per interval t cs cpu context switch rate (switches/interval) .El t cpu Breakdown of percentage usage of CPU time.
p l -tag -width indent -compact t us user time for normal and low priority processes t sy system time t id cpu idle .El .El .Sh EXAMPLES The command: .Dl 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 apparent which are recomputed every second. .Sh FILES l -tag -width /dev/kmemxxx -compact t Pa /kernel default kernel namelist t Pa /dev/kmem default memory file .El .Sh SEE ALSO .Xr fstat 1 , .Xr netstat 1 , .Xr nfsstat 1 , .Xr ps 1 , .Xr systat 1 , .Xr iostat 8 , .Xr pstat 8
p The sections starting with ``Interpreting system activity'' in .%T "Installing and Operating 4.3BSD" .