swap or not?

[Ivan Pulleyn]

What is kswapd doing when swap is off?

Ivan...


On Tue, 5 Feb 2002, Daniel Kidger wrote:

> -----Original Message-----
> From: Galen Arnold [mailto:arnoldg at ncsa.uiuc.edu]
> 
> >I'm looking for some opinions (based on real cluster setups would be nice 
> >too).  If you've got nodes with lots of memory (>1GB) do you run with swap 
> >space configured or not?
> 
> >We're seeing the occasional run that misses its memory request by a lot 
> >and it hangs nodes due to excessive paging.  
> 
> 
> I think that opinion is quite divided here.
> 
> There are still religious issues with the virtual memory subsystem in Linux.
> Even with swapoff, you can get kswapd taking lots of CPU time as memory
> usage gets close to the physical limit.
> 
> 
> Because some codes will leak memory by accident, use of 'ulimits' to limit
> the max. address space a user program can use will probably help more than
> having swap on or off. Also some resource managers / schedulers can police
> excessive memory usage.
> 
> 
> 
> 
> Yours,
> Daniel.
> 
> --------------------------------------------------------------
> Dr. Dan Kidger, Quadrics Ltd.      daniel.kidger at quadrics.com
> One Bridewell St., Bristol, BS1 2AA, UK         0117 915 5505
> ----------------------- www.quadrics.com --------------------
> 
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