Re: strange stack limit behavior when allocating more than 2GB mem on 32bit machine

Nicholas Mc Guire <[email protected]> Fri, 21 Aug 2009 11:37:50 +0200

Newsgroups	org.kernel.vger.linux-c-programming
Message-ID	<[email protected]>

On Fri, 21 Aug 2009, Joe wrote:

> Hi Glynn,
> 
> Thanks for your explanation. However as you can see, I got 2GB mem and
> ~10GB swap, totally 12GB.
> 
> With ulimit -s 10240(KB), I can allocate 2.5GB, I guess these are in
> swap, right?
> With ulimit -s unlimited, as you said, kernel reserved 1GB, stack
> reserved 2GB, there are still 12-3=9GB left??
> 
> Why did malloc failed, instead of allocating this abundant swap space?
>
initializing 12GB swap will not change the address space limit unless you
enabled high-memory support in the kernel (CONFIG_HIGHMEM64G=y in your .config)
the limit is not the physical memory (RAM+swap) but the 32bit address space.

hofrat