Vmstat

External

• http://www.lazysystemadmin.com/2011/04/understanding-vmstat-output-explained.html

Internal

• Linux

Overview

Reports virtual memory and other system statistics.

Output

procs -----------memory---------- ---swap-- -----io---- -system-- ------cpu-----
 r  b   swpd   free   buff  cache   si   so    bi    bo   in   cs us sy id wa st
 2  0      0 778480    700 156424    0    0   122     4   29   64  0  0 98  0  1

procs

r

The number of runnable processes (running or waiting for run time).

b

The number of processes in uninterruptible sleep. This is the size of the "wait queue" - processes that are waiting for I/O (disk, network, user input, etc.)

memory

swpd

The amount of virtual memory used. Represents how many blocks are swapped out to disk (paged). The same information can be obtained from /proc/swaps. To get the amount of swapped memory, in bytes, multiply the swpd value with the size of the block. This is how you can get the size of the page, in bytes. Is this really true? It contradicts with the data read from /proc/meminfo..

free

The amount of free memory.

buff

The amount of memory used as buffers.

cache

The amount of memory used as cache.

swap

si

Amount of memory swapped in from disk.

so

Amount of memory swapped to disk.

IO

b

Blocks received from a block device (blocks/s).

bo

Blocks sent to a block device (blocks/s).

system

in

The number of interrupts per second, including the clock.

cs

The number of context switches per second.

CPU

Also see Linux CPU Information.

us

Percentages of total CPU time spent running non-kernel code (user time, including nice time).

https://github.com/NovaOrdis/os-stats/blob/master/src/main/java/io/novaordis/osstats/metric/cpu/CpuUserTime.java

sy

Percentage of total CPU time spent running kernel code (system time).

id

Percentages of total CPU time spent idle.

wa

Percentages of total CPU time spent waiting for IO.

st

Time stolen from a virtual machine.

Continuous Readings

vmstat 1