Performance question

[Lindsay Snider]

On Wednesday 08 October 2003 16:10, Alan Fiebig wrote:
> >You want to be looking at the 'b' column not the 'r'.
>
> Ah, earlier I thought you literally meant the leftmost column, thanks for
> straightening me out! No wonder it looked so bad :)
>
> My 'b' column is usually '0' or '1', sometimes at 3-6 but only for an
> instant.

Do you get less 'b'locked processes when syslog is off?  Even one blocked 
process is enough for alarm if it sustained.  0/1 and sometimes 3-6 might be 
a little high.  If your processor can stay busy though, then you should be 
fine.

>
> So I guess I'm okay on that front.
>
> With children at 5 and syslog off:
>   load now is:     10.76, 8.07, 7.55
>   system time is:  40%-50%
>
> My idle time is way low, less than .5%, so I assume that this means my
> processor is now always able to both find something to do, and to actually
> do it.

That's good.  It's very likely SCSI disks would all you to run syslog w/o the 
processor blocking on disk i/o.

>
> Before, when I had high idle time, it was not due to a lack of work for the
> processor, but rather a lack of resources to do it. In the case of linux,
> lots of idle time coupled with there being a lot of work not getting done
> is indicative of a problem, in my case it is my disk IO apparently.

Yeah, and I think disk *tends* to be the culprit.  One thing to note, if the 
system doesn't have enough memory, you'll see lots of swapping in vmstat 
under SO/SI.  

>
> What should the system time percentage be at on a well tuned system? What's
> my target?

The best thing I would hope for would be 0% idle.  Then, you are processor 
bound, running the machine as fast as it can go.

>
> -Alan