Load Average Notes

Explain Load Average and vmstat

'vmstat 1' will give you stats for the system, including how many processes are waiting to be run, blocked in uninterruptable sleep and swapped out. These are the three first numbers ('r 'b' and 'w'):

bash-2.05a$ vmstat 1
   procs                      memory    swap          io     system         cpu
 r  b  w   swpd   free   buff  cache  si  so    bi    bo   in    cs  us  sy  id
 0  0  0  75780   4148  29212  83148   0   0     4     5   47    62   3   1  13
 1  0  0  75780   4140  29212  83148   0   0     0     0 1184   677   3   1  96

A process in uninterruptable sleep will add one to your load.

You could also use 'ps aux' to see in what state you processes are. The field STAT is where you get the state.

bash-2.05a$ ps aux 
USER       PID %CPU %MEM   VSZ  RSS TTY      STAT START   TIME COMMAND
root         1  0.0  0.0  1272   72 ?        S    Apr04   0:04 init [2] 
[...]
mysql     7048  0.0  6.8 1061200 140928 ?    D    Apr01   2:35
/usr/sbin/mysqld --basedir=/usr -- [...]

Here the mysqlprocess is in the "D"-state which is uninterruptable sleep, while init is in "S" - sleeping.

Also check the man pages for vmstat and ps for more detailed info on this.

(Stolen from)
Sigurd Urdahl                           sigurdur at linpro.no
Systemkonsulent | Systems consultant
Linpro A/S                                   www.linpro.no