Large memory issues on 4-STABLE

[Alex de Kruijff]

On Sat, Sep 13, 2003 at 03:48:21AM -0700, David G. Lawrence wrote:
> > David Lawrence said:
> > >   Sorry, due to design issues, it isn't possible to have virtual sizes
> > >larger than about 3GB on FreeBSD. This is because the kernel is mapped in
> > >the upper part of the virtual address space. Of course you can use all of
> > >your 4GB of RAM - just not all of it at the same time in one process.
> > 
> > OK, fair enough. Is this going to be any different in FreeBSD with PAE
> > (Intel's scheme for 32bit stuff using > 4GB RAM)?
> 
>    No, this has nothing to do with the size of physical memory. It is a limit
> on the size of a process's virtual address space.
>  
> > Should I try 5.1? Or isn't 4.9 going to have PAE support anyway?
> 
>    All versions of FreeBSD have this limitation.
>  
> > Given what David says though, why do I have a problem with MySQL getting
> > thread errors with MAXDSIZ 2048 or greater?
> > 
> > Why does tcsh's "limit" report datasize unlimited when MAXDSIZ is over
> > 2048?
> 
>    Probably a signed arithmetic problem. 2048MB is 2^31 bits, which is the
> largest number that can be represented in a 32 bit signed int.

Sorry but 2^31 is the lowest number availible in a 32 bit signed int and
2^31-1 is the largest number. The 32th bit indicates the number is
negitive.

-- 
Alex

Articles based on solutions that I use:
http://www.kruijff.org/alex/index.php?dir=docs/FreeBSD/