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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
 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.

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