For a typical performance monitoring all you need is only vmstat command. This display memory, swap, IO, system and cpu performance information.
The following command executes vmstat every 1 second for 100 times.
# vmstat 1 100 procs -----------memory---------- ---swap-- -----io---- --system-- ----cpu---- r b swpd free buff cache si so bi bo in cs us sy id wa 0 0 0 282120 134108 5797012 0 0 0 2 0 0 0 0 100 0 0 0 0 282120 134108 5797012 0 0 0 0 1007 359 0 0 100 0 0 0 0 282120 134108 5797012 0 0 0 0 1117 577 0 0 100 0 0 0 0 282120 134108 5797012 0 0 0 0 1007 366 0 0 100 0
Vmstat procs Section
- r field: Total number of runnable process
- b field: Total number of blocked process
Memory section
- Swpd field: Used swap space
- Free field: Available free RAM
- Buff field: RAM used for buffers
- Cache field: RAM used for filesystem cache
Swap Section
- Si field: Amount of memory swapped from disk per second
- So field: Amount of memory swapped to disk per second
IO Section
- Bi field: Blocks received from disk
- Bo field: Blocks sent to disk.
System Section
- In field: Number of interrupts per second.
- Cs field: Number of context switches per second.
CPU Section
- Us field: Time spend running user code. (non-kernel code)
- Sy field: Time spent running kernel code.
- Id field: Idle time.
- Wa field: Time spent waiting for the IO