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. Note: vmstat statistics are only supported for certain devices.

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. Note: interval and count do not apply to the −i and −s options. 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 general system statistics, use sar(1), iostat(1M), or sar(1M).

See Peripherals Administration for device naming conventions for disks.

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).

EXAMPLES

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

FILES

/dev/kmem

/dev/ksyms

/kernel/unix

Museum

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