understanding applications and PAE

[James Olin Oden]

On Mon, 8 Dec 2003, Vanco, Don wrote:

> While I hate to use this as a support line I've gotten no help from the 2
> local lugs I've queried, and know that there's some heavy hitters lurking
> here.
> 
> I understand that the Linux kernel can (through PAE) provide memory paging
> beyond 4GB of physical memory on 32-bit architecture.  What I need to
> understand is: what are the requirements on the application side to utilize
> this memory?  I'm looking for documentation / links that talk about
> applications and PAE.
> 
> Case in point: Lotus Notes on OS400 can address huge amount of RAM, but when
> it's running on Linux does it need to be compiled in a specific manner, or
> with some specific bit of code / API to address more than the architecture
> physically supports?
>
Hi Don,

We use the PAE feature where I work.  The deal is that this functionality 
only makes it possible for the kernel to access and use all this memory,
but each process still can only address 4Gig of memory less the amount of
memory under 4Gig the kernel is using.  If you wanted a single app
to use more than 4Gig, at this point you would need to create several
processes that share memory.  Even this this is very specific to the 
application as to whether such a scheme could be used effectively (you
would in effect be shuffling data around processes as needed).

Does anyone know of any other solutions than PAE?

Cheers...james 
> Thanx
> Don
> 
> 
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