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From: klingler@triton.unm.edu (David Klingler)
Newsgroups: comp.sys.next
Subject: Re: 8MB Blues (or M'ma vs VM)
Message-ID: <1991Mar11.084106.25135@ariel.unm.edu>
Date: 11 Mar 91 08:41:06 GMT
References: <1991Mar3.055657.3212@math.ucla.edu> <6863@idunno.Princeton.EDU> <SCOTT.91Mar5142921@mcs-server.gac.edu>
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Organization: University of New Mexico, Albuquerque NM
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In article <SCOTT.91Mar5142921@mcs-server.gac.edu> scott@mcs-server.gac.edu (Scott Hess) writes:
>In article <6863@idunno.Princeton.EDU> tvz@phoenix.Princeton.EDU (Timothy Van Zandt) writes:
>   In article <1991Mar3.055657.3212@math.ucla.edu> barry@pico.math.ucla.edu
>      (Barry Merriman) writes:
>
>   >to avoid these unsightly VM failures, get some more memory. 
>   >A total of 20MB RAM would appear sufficient for a single user
>   >(i.e. add 4 x 4MB). Also, remember you'll need to allow
>   >for a bigger swapfile as well on your hard disk. 
>
>   Why does increasing memory increase the required size of the swap
>   file? I heard this mentioned before, but it seems like the opposite
>   should be true.
>
>[This may or may not be true for Mach/Unix on the NeXT - it is true
> for regular Unix, and I'd give odds that it was for Mach/Unix, also]
>All memory used by processes must have space in the swapfile.  This
>space is allocated when the memory is allocated, needed or not.  In
>this way, you don't have programs run for a couple minutes then
>die when they are inactive and the swapper attempts to swap some of
>their data out so that another process can use memory - and there is
>no room.
>
>The generally recommended configuration for swapfiles is to allocate
>2x the real memory size for the minimum size of the swapfile (obviously,
>it can grow to fill the disk it's on, under Mach).  You don't have
>to do this - it's just a recommendation.  In general, if you need
>20M of memory, you'll probably end up with a 40M swapfile, anyhow.
>You cannot count on disk space freed up by shrinking the lowater
>size of the swapfile, because almost certainly you will need it
>back at some point in the future, anyhow.
>
>Later
>--
>scott hess                      scott@gac.edu
>Independent NeXT Developer	GAC Undergrad
><I still speak for nobody>
>"Tried anarchy, once.  Found it had too many constraints . . ."
>"I smoke the nose Lucifer . . . Bannana, banna."

Okay.  I've added another 8 megs.  But how do I go about changing my swapfile
size?  Especially when the bug list in the man entry says that a swapfile 
cannot be deactivated when in use?  I'm beginning to think the fact that
I haven't modified my swapfile size is responsible for a few nasty crashes...

Dave
klingler@triton.unm.edu