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Ossi February 28, 2003 08:22

RAMFILES 1 or 0 ?
 
Hi, does anybody know what is the difference in writing the temporary files to the disc (RAMFILES 1) or not writing (RAMFILES 0) ? At least it takes some space when the files are written to the disc but other than that, are there any pros if not writing the temporary files to the disc ?

Marc February 28, 2003 10:52

Re: RAMFILES 1 or 0 ?
 
Hey Ossi.
If not writing them to disk, you have to keep them somewhere. They will be kept in RAM, thats why the fuction is called RAMFILES. It will be significant faster to keep the files in memory, but unfortunately you will need very much physical memory (depending on the size of the job).
Greetings, Marc

Ossi February 28, 2003 10:59

Re: RAMFILES 1 or 0 ?
 
Thanks ! Ossi

Steve February 28, 2003 11:25

Re: RAMFILES 1 or 0 ?
 
If you're doing some really Noddy model for testing purposes (a few hundred cells perhaps), RAMFILES=1 really speeds things up.


cjtune March 1, 2003 01:17

Re: RAMFILES 1 or 0 ?
 
At any rate, you wouldn't want to run out of RAM. Things become really slow (by one to two orders or magnitude) when the temporary data 'spills' over to your hard disk swap file(s).

So at the limiting condition of having barely enough RAM, is it better to have RAMFILES=1 or =0?

steve March 1, 2003 14:50

Re: RAMFILES 1 or 0 ?
 
Using ramfiles is as fast or faster than not when you do not run out of physical memory. If you run out of physical memory and start swapping, then using ramfiles is usually significantly worse. The reason is that the data put on the scratch files is put there intelligiently when its not likely to be used for a while. If you just let the system swap, it really cannot match the intelligience of a programmer who knows exactly what data is needed and when. If your are marginal on ram, I would suggest not using ramfiles.

cjtune March 2, 2003 02:38

Re: RAMFILES 1 or 0 ?
 
Makes sense... otherwise why have the RAMFILES variable at all?


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