Nix: Monitor System Memory with vmstat

vmstat allows the user to monitor virtual memory statistics such as processes, memory, paging, block IO, traps, disks and cpu activity.

The user can specify a sampling period.

$ vmstat 1
procs -----------memory----------
r  b   swpd   free   buff  cache
4  0 920708  74004  36324 114148
---swap-- -----io---- -system--
si   so    bi    bo   in   cs
29   53   125   112  298  212
----cpu----
us sy id wa
26  6 65  3

The above will run vmstat every second and display system virtual memory usage such as:

• r number process waiting to run,
• b blocked process,
• swpd virtual memory used,
• free idle memory,
• bi, bo number of blocks sent and received from disk,
• us time spent in user code, or
• sy time spent in kernel code.

As current Linux blocks are 1024 bytes, vmstat uses the same unit of measurement for memory.

Via enki.com.