vmstat Command Cheat Sheet

vmstat (virtual memory statistics) reports information about processes, memory, paging, block IO, traps, and CPU activity.

Synopsis

vmstat [options] [delay [count]]

Basic Usage

Snapshot

vmstat

Continuous Monitoring (Every 1 second)

vmstat 1

Understanding Output Columns

Procs

• r: The number of runnable processes (waiting for run time).
• b: The number of processes in uninterruptible sleep.

Memory

• swpd: Amount of virtual memory used.
• free: Amount of idle memory.
• buff: Amount of memory used as buffers.
• cache: Amount of memory used as cache.

Swap

• si: Amount of memory swapped in from disk (/s).
• so: Amount of memory swapped to disk (/s).

IO

• bi: 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

• us: Time spent running non-kernel code. (user time, including nice time)
• sy: Time spent running kernel code. (system time)
• id: Time spent idle.
• wa: Time spent waiting for IO.
• st: Time stolen from a virtual machine.

Options

Display Unit (-S)

Switch to Megabytes.

vmstat -S M

Active/Inactive Memory (-a)

Display active/inactive memory instead of buffer/cache.

vmstat -a

Disk Statistics (-d)

Detailed breakdown of read/writes per disk partition.

vmstat -d