memory allocation on linux

memory allocation on linux

[Cannizzaro, Emanuele]

I am writing to you regarding your experience to address a huge amount of 
memory on linux using the brk() function.

I am running a program called nastran (v2001) on a pc with redhat 7.2. This 
machine has got 2GB of disk spacebut  when I set the amount of memory to be 
used by nastran to a value bigger than 900 mb I get this fatal error message.

Process Id = 28179
idalloc: dynamic allocation failed - brk: Cannot allocate memory
   requested size: 402653184 words (1572864 kbytes)
   starting address:           0x0a300000 ( 170917888)
   maximum address requested:  0x6a300080 (1781530752)
 08:08:18  MAINAL: *** OPEN CORE MEMORY ALLOCATION FAILED *** ERROR =         
 1
 08:08:18  MAINAL: *** MEMORY REQUESTED =    402653184 ***
 08:08:18  MAINAL: *** PROCESSING TERMINATED ***
 08:08:18  Analysis complete  8
STOP OPEN CORE Allocation Failed statement executed

I have no access to the source code of the program and therefore I would need 
a patch to the memory allocation.

how can this problem be fixed?

Thanks in advance for your help

Emanuele Cannizzaro
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Re: memory allocation on linux

[Lee Chin]

Hi
>If you link your program statically
>you might be able to get up to nearly 3 GB of >memory for your
>process, but that's the limit...
Is that on a 32 bith machine that I can get upto 3GB?  I have linked statically, but yet I max out at 2 GB.  I thoiught with th elatest kernel, which already includes the BIGMEM patch, I should be able to go upto 3GB.

Thanks
Lee

----- Original Message -----
From: Rik van Riel <riel@conectiva.com.br>
Date: 	Thu, 19 Sep 2002 22:03:31 -0300 (BRT)
To: Lee Chin <leechin@mail.com>
Subject: Re: memory allocation on linux


> On Thu, 19 Sep 2002, Lee Chin wrote:
> 
> > I have a process trying to allocate a large amount of memory.
> > I have 4 GB physical memory in the system and more with swap space.
> 
> > However, I am unable to allocate more than 2GB for my process.
> > How can I acheive this?
> 
> Switch to a 64-bit CPU.  If you link your program statically
> you might be able to get up to nearly 3 GB of memory for your
> process, but that's the limit...
> 
> Rik
> -- 
> Bravely reimplemented by the knights who say "NIH".
> 
> http://www.surriel.com/		http://distro.conectiva.com/
> 
> Spamtraps of the month:  september@surriel.com trac@trac.org
> 
> 

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Re: memory allocation on linux

[Rik van Riel]

On Thu, 19 Sep 2002, Lee Chin wrote:

> I have a process trying to allocate a large amount of memory.
> I have 4 GB physical memory in the system and more with swap space.

> However, I am unable to allocate more than 2GB for my process.
> How can I acheive this?

Switch to a 64-bit CPU.  If you link your program statically
you might be able to get up to nearly 3 GB of memory for your
process, but that's the limit...

Rik
-- 
Bravely reimplemented by the knights who say "NIH".

http://www.surriel.com/		http://distro.conectiva.com/

Spamtraps of the month:  september@surriel.com trac@trac.org

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Re: memory allocation on linux

[Lee Chin]

Hello,
I downloaded the latest 2.5 Kernel.

I have a process trying to allocate a large amount of memory.

I have 4 GB physical memory in the system and more with swap space.

I have the kernel compiled with 8GB memory support.

However, I am unable to allocate more than 2GB for my process.

How can I acheive this?

Thanks
Lee
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Re: memory allocation on linux

[Rik van Riel]

On Wed, 7 Aug 2002, Cannizzaro, Emanuele wrote:

> I am writing to you regarding your experience to address a huge amount of
> memory on linux using the brk() function.
>
> I am running a program called nastran (v2001) on a pc with redhat 7.2. This
> machine has got 2GB of disk spacebut  when I set the amount of memory to be
> used by nastran to a value bigger than 900 mb I get this fatal error message.
>
> Process Id = 28179
> idalloc: dynamic allocation failed - brk: Cannot allocate memory

The problem is that you have your libc mapped at 1GB offset
and the program executable at 128 MB, leaving about 900 MB
of space for brk().

> I have no access to the source code of the program and therefore I would
> need a patch to the memory allocation.
>
> how can this problem be fixed?

If the program is dynamically linked you could try using a
libc that uses malloc() instead of brk().

If the program uses brk, you could hack the kernel to start
mmap() at a different offset (eg 2 GB).

The easiest and arguably best option would be to link the
program statically so it doesn't have to mmap any libraries,
but it seems like you're stuck with whatever binary was given
to you so you'll have to work around the problem...

regards,

Rik
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Bravely reimplemented by the knights who say "NIH".

http://www.surriel.com/		http://distro.conectiva.com/

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