Max Heap Size on Itanium

Boehm, Hans hans_boehm@hp.com
Tue Jul 9 11:27:00 GMT 2002


This hasn't been thoroughly tested, but ...

By default the hard limit should be at least 6GB.  You will however get some spurious collisions in bit hash tables starting at around 0.5GB, which may or may not have a performance impact.  Building the collector with -DLARGE_CONFIG should increase both numbers, with the second number going to around 4GB.  If you need more than that, this is still relatively easy to change.  The cost is additional overhead in a few statically allocated one-bit-per-page bit maps.  Some of the standard numbers should probably be increased (again).

There has been some effort to get the collector to work with a 3GB heap on X86/Linux, though some of that code is not in the gcc tree yet.  One or two people have ended up using it as a malloc replacement solely to get access to more of the address space. 

Hans

> -----Original Message-----
> From: Markus Bernhardt [mailto:mbernhardt@swsgmbh.de]
> Sent: Tuesday, July 09, 2002 4:25 AM
> To: java@gcc.gnu.org
> Subject: Max Heap Size on Itanium
> 
> 
> Hi all,
> 
> what's the maximum heap size on IA-64
> machines ? More than 2GB ?
> 
> Thanks.
> 
> - markus
> 



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