Justin -
I think I have heard something along those lines but I'm not certain.
However, if it's true - that 128MB is the largest useful size for swap
partitions, don't sweat - I think Linux will recognize more than one swap
partition. If you put them on separate non-RAID drives, you should get a
speed boost (if your drives are IDE, stick to one drive per controller;
don't put them on two drives on the same controller {I don't recommend
putting two drives on the same controller anyway unless capacity matters
more to you than speed}).
How this would work on a Beowulf cluster would depend a lot on what you're
running, but as a general guideline, I would think that if your situation is
such that your nodes are doing a lot of swapping, then you're working
against yourself; you'd be better off breaking the problem into smaller
chunks in order to mostly stay within the RAM your nodes actually have.
Cluster nodes that don't have to run their own drives very much would be
happy nodes, IMHO. Problems that require you to write giant data sets all
during the run might be an exception. You have a choice: write the
solution in pieces to each node's drive for later assembly or write all the
pieces back to a central location. Either way, swapping is to be shunned.
- Jeff
> -----Original Message-----
> From: Justin Russell [mailto:">justin.w.russell@lmco.com]
> Sent: Tuesday, April 18, 2000 5:19 PM
> To: ">ale@ale.org
> Subject: [ale] Kernel limitation?
>
>
> I just had someone tell me something that surprised me and I wanted
> other input.
> He said that he was told that Linux accesses only the first 128 MB of
> swap. Is this true? So if I set up a 1 Gig swap partition, I can't
> allocate 1 Gig of memory? Has anyone tried this? Is it
> different on a
> Beowulf cluster (swap/node)?
> Any info is helpful.
>
> Thanks,
> Justin
>
> --
> -----------------------------------------------
> Justin W. Russell
> Senior Engineer, Aerodynamics/CFD
> Lockheed Martin Aeronautics Company - Marietta
> 86 South Cobb Drive
> Marietta, GA 30063-0685
>
> Tel: (770) 494-6303
> Fax: (770) 494-3055
> -----------------------------------------------
>
>
>
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