Date: Mon, 28 Jul 2003 01:37:30 -0700
From: jw schultz <jw@pegasys.ws>
To: linux-kernel@vger.kernel.org
Subject: Re: malloc problem to allocate very large blocks
Message-ID: <20030728083730.GB1333@pegasys.ws>
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On Mon, Jul 28, 2003 at 02:44:28PM +0800, Tung-Han Hsieh wrote:
> Hello,
> 
> I am developing applications which requires more than 2GB memory.
> But I found that in my Linux system the malloc() cannot allocate
> more than 2GB memory. Here is the details of my system:

Malloc is a library function, not a syscall.

That said i'm not surprised.  Malloc front-ends sbrk and
sometimes mmap.  Sbrk uses a ptrdiff_t to indicate the size
desired.  ptrdiff_t is signed and on 32 bit platforms should
be 32 bits.  Therefore, the maximum you can allocate at one
time with sbrk is going to be 2GB.  That malloc would
inherit this limitation is to be expected.

If you need to allocate that much memory in one chunk, don't
use malloc.

-- 
________________________________________________________________
	J.W. Schultz            Pegasystems Technologies
	email address:		jw@pegasys.ws

		Remember Cernan and Schmitt
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