More then 2G of memory per process

Bill Rankin wrankin at
Wed Aug 6 17:10:01 CDT 2003

From: Matt Domsch <Matt_Domsch at>

> > I'm running an application that was developed in house. We are starting
> > to exceed the limit of approximately 2 gigs of memory per application.
> > Are there any options that will allow us to increase this limit?
> Red Hat Enterprise Linux 3 public beta "Taroon" has a 'bigmem' kernel 
> which implements a 4GB kernel / 4GB user memory split.  This increases the 
> amount of address space available to user processes from 3GB to just under 
> 4GB, which should help a good bit.  It *really* helps the kernel, as it 
> now gets 4GB of address space, up from 1GB previously.

Can you elaborate (or post a URL) with the details of this enhancement?
I am very interested in seeing where this memory getts freed from and
how we can use it to get around the 1-2 GB limit on contiguous data
structures (in FORTRAN).



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