Subject: CCL:Swap Space on Unix

From: "Jochen Küpper" <[email-masked]>
Date: Wed, 2 Feb 2000 23:12:12 +0100 (CET)

Peter Shenkin writes:

 > Well, if the jobs are really swapping then you will probably
 > be greatly slowed down by this strategy, but it ought to be
 > harmless from a system point of view.

Yep, but you really have to stress that Gaussian's out-of-memory
algorithms are better fopr Gaussian than the generic OS demand
paging.

 > There is also a way to configure DECs to "overcommit" virtual
 > memory.

Yes, sometimes very usefull.

 > I don't know whether G98 is careful never to allocate more 
 > memory than it needs, but if it sometimes does allocate 
 > more than it actually uses, configuring your OS this way 
 > would be another way to go.

Me too, but my jobs usually have an RSS close to size at one point, so 
I guess it uses all the allocated memory (at least within my
applications). 

 > BTW, your Subject: refers to a UNIX question, but in fact
 > the answer differs for different flavors of UNIX.  The above
 > is correct for TRU64, AFAIK.  

Yep. Some *nices do overcommitment by default, others need to be
configured that way (like Tru64).
Is therone out that doesn't do it at all - I assume not.

Jochen
--
Heinrich-Heine-Universität
Institut für Physikalische Chemie I
Jochen Küpper
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