Re: 32 bit malloc on x86_64

[Jeremy Sanders <jss at ast dot cam dot ac dot uk>]

On Tue, 8 Jul 2008, Carlos O'Donell wrote:

> On Mon, Jul 7, 2008 at 12:49 PM, Jeremy Sanders <jss@ast.cam.ac.uk> wrote:
> > I have come up with a workaround, which is to use mmap myself to allocate
> > the memory with the MAP_32BIT flag. This appears to work okay in test I have
> > done, but it is a pain as I have to keep track of the allocated length for
> > munmap. I read that MAP_32BIT really only gives you 31 bits of memory, but
> > this program doesn't use huge amounts of memory.
> >
> > Is this a sensible way to proceed?
>
> It seems perfectly sensible. Why is this a pain? Isn't it only one
> mmap, and at program exit one munmap?

The program allocates memory and deallocates it as it runs, so there's no 
fixed size block of memory. My mmap code seems to work, but I just wanted 
to know whether there is a better solution, and why the mallopt command is 
now being ignored by linux/glibc.

Thanks

Jeremy

--
Jeremy Sanders <jss@ast.cam.ac.uk>   http://www-xray.ast.cam.ac.uk/~jss/
X-Ray Group, Institute of Astronomy, University of Cambridge, UK.
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