New libc malloc patch

Jason Evans jasone at
Fri Dec 2 23:50:27 PST 2005

On Nov 29, 2005, at 12:06 PM, Jon Dama wrote:
> There exists a problem right now--localized to i386 and any other arch
> based on 32-bit pointers: address space is simply too scarce.
> Your decision to switch to using mmap as the exclusive source of  
> malloc
> buckets is admirable for its modernity but it simply cannot stand  
> unless
> someone steps up to change the way mmap and brk interact within the
> kernel.

There's a new version of the patch available at:

This version of the patch adds the following:

* Prefer to use sbrk() rather than mmap() for the 32-bit platforms.

* Lazily create arenas, so that single-threaded applications don't  
dedicate space to arenas they never use.

* Add the '*' and '/' MALLOC_OPTIONS flags, which allow control over  
the number of arenas.

As of this patch, all of the issues that were brought to my attention  
have been addressed.  This is a good time for additional review and  
serious benchmarking.


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