vmstat(1M)

NAME

vmstat − report virtual memory statistics

SYNOPSIS

vmstat [ −cisS ] [ disks ] [ interval [ count ] ]

DESCRIPTION

vmstat delves into the system and reports certain statistics kept about process, virtual memory, disk, trap and CPU activity.

Without options, vmstat displays a one-line summary of the virtual memory activity since the system was booted. If interval is specified, vmstat summarizes activity over the last interval seconds, repeating forever. If a count is given, the statistics are repeated count times. If disks are specified, they are given priority when vmstat chooses which disks to display (only four fit on a line). Common disk names are id, sd, xd, or xy, followed by a number, for example, sd2, xd0, and so forth. For more detailed disk statistics, use iostat(1M) or sar(1M).

For example, the following command displays a summary of what the system is doing every five seconds.

example% vmstat 5
procs     memory              page               disk       faults     cpu
r b w swap free re mf pi po fr de sr s0 s1 s2 s3 in sy cs us sy id
0 0 0 11456 4120   1   41   19    1    3   0   2    0   4    0   0 48 112 130 4 14 82
0 0 1 10132 4280   0    4    44    0    0   0    0   0 23   0   0 211 230 144 3 35 62
0 0 1 10132 4616   0    0    20    0    0   0    0   0 19   0   0 150 172 146 3 33 64
0 0 1 10132 5292   0    0     9     0    0   0    0   0 21   0   0 165 105 130 1 21 78
1 1 1 10132 5496   0    0     5     0    0   0    0   0 23   0   0 183 92 134 1 20 79
1 0 1 10132 5564   0    0    25    0    0   0    0   0 18   0   0 131 231 116 4 34 62
1 0 1 10124 5412   0    0    37    0    0   0    0   0 22   0   0 166 179 118 1 33 67
1 0 1 10124 5236   0    0    24    0    0   0    0   0 14   0   0 109 243 113 4 56 39
^C
example%

The fields of vmstat’s display are:

procs Report the number of processes in each of the three following states:

r in run queue

b blocked for resources (I/O, paging, and so forth)

w runnable but swapped

memory
Report on usage of virtual and real memory.

swap amount of swap space currently available (Kbytes)

free size of the free list (Kbytes)

page Report information about page faults and paging activity. The information on each of the following activities is given in units per second.

re page reclaims — but see the −S option for how this field is modified.

mf minor faults — but see the −S option for how this field is modified.

pi kilobytes paged in

po kilobytes paged out

fr kilobytes freed

de anticipated short-term memory shortfall (Kbytes)

sr pages scanned by clock algorithm

disk Report the number of disk operations per second. There are slots for up to four disks, labeled with a single letter and number. The letter indicates the type of disk (s = SCSI, i = IPI, and so forth); the number is the logical unit number.

faults Report the trap/interrupt rates (per second).

in (non clock) device interrupts

sy system calls

cs CPU context switches

cpu Give a breakdown of percentage usage of CPU time. On MP systems, this is an average across all processors.

us user time

sy system time

id idle time

OPTIONS

−c Report cache flushing statistics. By default, report the total number of each kind of cache flushed since boot time. The types are: user, context, region, segment, page, and partial-page.

−i Report the number of interrupts per device.

−s Display the total number of various system events since boot.

−S Report on swapping rather than paging activity. This option will change two fields in vmstat’s “paging” display: rather than the “re” and “mf” fields, vmstat will report “si” (swap-ins) and “so” (swap-outs).

FILES

/dev/kmem

/dev/ksyms

/kernel/unix

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