[oclug] TOP interpretation

[OddSox]

On Jun 26, 2009, at 12:33 PM, Damian Gerow wrote:

> OddSox wrote:
> : Further to my last message, I'm trying to figure out the  
> significance
> : of the various CPU numbers in TOP on my CentOS 5.x server...
> :
> : > Cpu(s):  0.3%us,  0.0%sy,  0.0%ni, 99.7%id,  0.0%wa,  0.0%hi,   
> 0.0%si,  0.0%st
> :
> :
> : What does 99.7%id mean?
>
> %us = user
> %sy = system
> %ni = nice
> %id = idle
> %wa = wait
> %hi = ?
> %si = system interrupts?
> %st = ?

Idle! I knew that, just forgot.


> I've never seen those last three, but it's been a few years since I  
> bothered
> with 'top' in Linux.  System performance is a notoriously difficult  
> thing to
> measure and understand...

It would also help if the numbers actually added up to 100% but often  
they don't. I know one sysadmin who insists that if your CPU isn't  
spiking 100% then you're not using your machine properly...

Thanks.

> user = amount of time the system is running userland code
> system = amount of time the system is running kernel code
> nice = I've never really understood this one
> idle = amount of time the system is doing nothing
> wait = amount of time the system is waiting for available CPU cycles
>
> Or something like that.
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