Vmstat

System monitoring with vmstat

The following results were obtained based on data collected using vmstat, a tool that reports a system's virtual memory statistics.

In order to reproduce the output shown in section 2, one should:

• Fetch upstream code from the core-image-minimal recipes

$ git clone git://git.yoctoproject.org/poky
$ cd poky/
$ source oe-init-build-env
$ echo -e 'DL_DIR = "/home/user/poky/downloads"' > conf/auto.conf
$ bitbake core-image-minimal -c fetchall

• Start vmstat in a new terminal (set a 2 sec interval)

$ vmstat 2 > vmstat-output.raw

• On the terminal from the first step, launch bitbake, making sure no network activity will be done

$ echo -e 'BB_NO_NETWORK = "1"' >> conf/auto.conf
$ bitbake core-image-minimal

• Once bitbake finishes, Ctrl+D the vmstat command to stop it

Vmstat output

Processing jobs

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

Test2

Memory usage

  Memory
      swpd: the amount of virtual memory used.
      free: the amount of idle memory.
      buff: the amount of memory used as buffers.
      cache: the amount of memory used as cache.

IO activity

  IO
      bi: Blocks received from a block device (blocks/s).
      bo: Blocks sent to a block device (blocks/s).

System operations

  System
      in: The number of interrupts per second, including the clock.
      cs: The number of context switches per second.

CPU performance

  CPU
      These are percentages of total CPU time.
      us: Time spent running non-kernel code.  (user time, including nice time)
      sy: Time spent running kernel code.  (system time)
      id: Time spent idle.  Prior to Linux 2.5.41, this includes IO-wait time.
      wa: Time spent waiting for IO.  Prior to Linux 2.5.41, included in idle.
      st: Time stolen from a virtual machine.  Prior to Linux 2.6.11, unknown.