thrashing

Jeffrey B. Layton laytonjb at bellsouth.net
Thu Aug 28 14:39:02 EDT 2003


Use vmstat. Try something like,

vmstat 1 10

(1 second delay, 10 repeats). Look in the columns labeled,

 swap
si   so

that will give you the information you want.

Good Luck!

Jeff


> 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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