6. Memory Monitoring

Lesson Content

In addition to CPU monitoring and I/O monitoring you can monitor your memory usage with vmstat

pete@icebox:~$ vmstat
procs -----------memory---------- ---swap-- -----io---- -system-- ------cpu-----
 r  b   swpd   free   buff  cache   si   so    bi    bo   in   cs us sy id wa st
 1  0      0 396528  38816 384036    0    0     4     2   38   79  0  0 99  0  0

The fields are as follows:

procs

  • r - Number of processes for run time
  • b - Number of processes in uninterruptible sleep

memory

  • swpd - Amount of virtual memory used
  • free - Amount of free memory
  • buff - Amount of memory used as buffers
  • cache - Amount of memory used as cache

swap

  • si - Amount of memory swapped in from disk
  • so - Amount of memory swapped out to disk

io

  • bi - Amount of blocks received in from a block device
  • bo - Amount of blocks sent out to a block device

system

  • in - Number of interrupts per second
  • cs - Number of context switches per second

cpu

  • us - Time spent in user time
  • sy - Time spent in kernel time
  • id - Time spent idle
  • wa - Time spent waiting for IO

Exercise

Look at your memory usage with vmstat.

Quiz Question

# What tool is used to view memory utilization? >The vmstat command (short for virtual memory statistics) is a built-in monitoring utility in Linux. The command is used to obtain information about memory, system processes, paging, interrupts, block I/O, disk, and CPU scheduling. Users can observe system activity virtually in real-time by specifying a sampling period. 1. [x] vmstat 2. [ ] init 3. [ ] unstart 4. [ ] iostat