6. Memory Monitoring

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