thrashing

Joseph Landman landman at scalableinformatics.com
Thu Aug 28 15:08:53 EDT 2003


Hi Glen:

  Several methods.

1) vmstat

	vmstat 1

and look at the so/si columns, not to mention the r/b/w.

2) swapon -s

to see the swap usage

3) top

has an ok summary of the vm info

4) cat /proc/meminfo 

can give a crude picture of the memory system.

On Thu, 2003-08-28 at 14:19, Glen Kaukola wrote:
> Hi there,
> 
> So for our newest simulations, we're working with a different domain, 
> where each of our grid cells are much smaller, and so we're expecting 
> the runs to take about 4 times longer.  But actually they're taking 
> around 40 times longer.  I'm thinking this may have something to do with 
> not having enough memory.  The problem with this theory is that I'm not 
> really sure how to tell if my machines are thrashing.  On a desktop 
> machine I can tell no problem, as the disk starts going crazy and the 
> system pretty much grinds to a halt.  But on a machine up in my server 
> room on which I don't have any gui and where it's too loud to hear any 
> disk activity, I'm really not sure how to tell whether it's thrashing or 
> not.  I mean, I can look at top, and free, and sar and everything 
> doesn't look much different than when the other simulations were 
> running, except for maybe 'sar -W', which is a little bit higher.  
> Anyway, if someone could help me out with a way to determine without a 
> doubt if my machines are thrashing or not, then I'd greatly appriciate it.
> 
> Thanks for your time,
> Glen Kaukola
> 
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-- 
Joseph Landman, Ph.D
Scalable Informatics LLC
email: landman at scalableinformatics.com
  web: http://scalableinformatics.com
phone: +1 734 612 4615


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