Max mem space per process under 2.6.13-15.7-smp

Max mem space per process under 2.6.13-15.7-smp

[Kai Lampka]

Sorry to bother, 
but what is the maximum amount of RAM that a *single* (!) process can
address under a Kernel version 2.6.13-15.7-smp, with 

CONFIG_HIGHMEM64G=y
CONFIG_HIGHMEM=y
CONFIG_X86_PAE=y

It seems that I can not get over 3 Gig border, but i need to, to solve
my numerical problems :(.


Greetings Kai

Re: Max mem space per process under 2.6.13-15.7-smp

[Douglas McNaught]

Kai Lampka <kilampka@gmail.com> writes:

> Sorry to bother, 
> but what is the maximum amount of RAM that a *single* (!) process can
> address under a Kernel version 2.6.13-15.7-smp, with 
>
> CONFIG_HIGHMEM64G=y
> CONFIG_HIGHMEM=y
> CONFIG_X86_PAE=y
>
> It seems that I can not get over 3 Gig border, but i need to, to solve
> my numerical problems :(.

I've heard of a kernel patch that gives you 3.5GB (leaving 0.5 for
the kernel) but you're not going to get any more than that without
buying a 64-bit machine or playing overlay tricks with mmap().  Given
the price and performance of 64-bit hardware, the former option is
probably a lot better.

-Doug

Re: Max mem space per process under 2.6.13-15.7-smp

[Robert Hancock]

Kai Lampka wrote:
> Sorry to bother, 
> but what is the maximum amount of RAM that a *single* (!) process can
> address under a Kernel version 2.6.13-15.7-smp, with 
> 
> CONFIG_HIGHMEM64G=y
> CONFIG_HIGHMEM=y
> CONFIG_X86_PAE=y
> 
> It seems that I can not get over 3 Gig border, but i need to, to solve
> my numerical problems :(.

If you use a kernel with the 4G-4G user-kernel space split patch, you 
can get a full 4GB. To get more than that you will need to move to 64-bit.

-- 
Robert Hancock      Saskatoon, SK, Canada
To email, remove "nospam" from hancockr@nospamshaw.ca
Home Page: http://www.roberthancock.com/

Re: Max mem space per process under 2.6.13-15.7-smp

[Arjan van de Ven]

> It seems that I can not get over 3 Gig border, but i need to, to solve
> my numerical problems :(.

get a 64 bit machine...

you can get upto 4Gb if you use a kernel with the 4g/4g patch (which is
mostly old FC2 kernels and RHEL4 kernels at this point, it's a dying
breed)