Displaying Virtual Memory Statistics (vmstat)

You can use the vmstat command to report virtual memory statistics and information about system events such as CPU load, paging, number of context switches, device interrupts, and system calls. The vmstat command can also display statistics on swapping, cache flushing, and interrupts.

The following table describes the fields in the vmstat command output.

Table 13-1 Output From the vmstat Command

Category	Field Name	Description
procs		Reports on the following:
	r	The number of kernel threads in the dispatch queue
	b	The number of blocked kernel threads that are waiting for resources
	w	The number of swapped out LWPs that are waiting for processing resources to finish
memory		Reports on usage of real memory and virtual memory:
	swap	Available swap space
	free	Size of the free list
page		Reports on page faults and paging activity, in units per second:
	re	Pages reclaimed
	mf	Minor faults and major faults
	pi	Kbytes paged in
	po	Kbytes paged out
	fr	Kbytes freed
	de	Anticipated memory that is needed by recently swapped-in processes
	sr	Pages scanned by the page daemon not currently in use. If sr does not equal zero, the page daemon has been running.
disk		Reports the number of disk operations per second, showing data on up to four disks
faults		Reports the trap/interrupt rates per second:
	in	Interrupts per second
	sy	System calls per second
	cs	CPU context switch rate
cpu		Reports on the use of CPU time:
	us	User time
	sy	System time
	id	Idle time

For a more detailed description of this command, see the vmstat(1M) man page.

How to Display Virtual Memory Statistics (vmstat)

• Collect virtual memory statistics by using the vmstat command with a time interval in seconds.

  $ vmstat n

  where n is the interval in seconds between reports.

Example 13-1 Displaying Virtual Memory Statistics

The following example shows the vmstat display of statistics that were gathered at five-second intervals.

$ vmstat 5
kthr      memory            page            disk          faults      cpu
 r b w   swap  free  re  mf pi po fr de sr dd f0 s1 --   in   sy   cs us sy id
 0 0 0 863160 365680  0   3  1  0  0  0  0  0  0  0  0  406  378  209  1  0 99
 0 0 0 765640 208568  0  36  0  0  0  0  0  0  0  0  0  479 4445 1378  3  3 94
 0 0 0 765640 208568  0   0  0  0  0  0  0  0  0  0  0  423  214  235  0  0 100
 0 0 0 765712 208640  0   0  0  0  0  0  0  3  0  0  0  412  158  181  0  0 100
 0 0 0 765832 208760  0   0  0  0  0  0  0  0  0  0  0  402  157  179  0  0 100
 0 0 0 765832 208760  0   0  0  0  0  0  0  0  0  0  0  403  153  182  0  0 100
 0 0 0 765832 208760  0   0  0  0  0  0  0  0  0  0  0  402  168  177  0  0 100
 0 0 0 765832 208760  0   0  0  0  0  0  0  0  0  0  0  402  153  178  0  0 100
 0 0 0 765832 208760  0  18  0  0  0  0  0  0  0  0  0  407  165  186  0  0 100

How to Display System Event Information (vmstat -s)

• Run the vmstat -s command to show how many system events have taken place since the last time the system was booted.

  $ vmstat -s
          0 swap ins
          0 swap outs
          0 pages swapped in
          0 pages swapped out
     522586 total address trans. faults taken
      17006 page ins
         25 page outs
      23361 pages paged in
         28 pages paged out
      45594 total reclaims
      45592 reclaims from free list
          0 micro (hat) faults
     522586 minor (as) faults
      16189 major faults
      98241 copy-on-write faults
     137280 zero fill page faults
      45052 pages examined by the clock daemon
          0 revolutions of the clock hand
         26 pages freed by the clock daemon
       2857 forks
         78 vforks
       1647 execs
   34673885 cpu context switches
   65943468 device interrupts
     711250 traps
   63957605 system calls
    3523925 total name lookups (cache hits 99%)
      92590 user   cpu
      65952 system cpu
   16085832 idle   cpu
       7450 wait   cpu

How to Display Swapping Statistics (vmstat -S)

• Run vmstat -S to show swapping statistics.

  $ vmstat -S
  kthr      memory            page            disk          faults      cpu
   r b w   swap  free  si  so pi po fr de sr dd f0 s1 --   in   sy   cs us sy id
   0 0 0 862608 364792  0   0  1  0  0  0  0  0  0  0  0  406  394  213  1  0 99

  The swapping statistics fields are described in the following list. For a description of the other fields, see Table 13-1.

  si

  Average number of LWPs that are swapped in per second

  so

  Number of whole processes that are swapped out

  ---

  Note - The vmstat command truncates the output of si and so fields. Use the sar command to display a more accurate accounting of swap statistics.

  ---

How to Display Interrupts Per Device (vmstat -i)

• Run the vmstat -i command to show the number of interrupts per device.

Example 13-2 Displaying Interrupts Per Device

The following example shows output from the vmstat -i command.

$ vmstat -i
interrupt         total     rate
--------------------------------
clock          52163269      100
esp0            2600077        4
zsc0              25341        0
zsc1              48917        0
cgsixc0             459        0
lec0             400882        0
fdc0                 14        0
bppc0                 0        0
audiocs0              0        0
--------------------------------
Total          55238959      105