AIX offers two memory management extensions:

The Default Memory Allocator with the Malloc Buckets Extension -- From
section 4.2.3 of Developing and Porting and C++ Applications on AIX at
http://www.redbooks.ibm.com/redbooks/pdfs/sg245674.pdf:
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The default memory allocator with the malloc buckets extension, or
simply malloc buckets, provides an optional buckets-based extension of
the default allocator. It is intended to improve malloc subsystem
performance for applications that issue large numbers of small
allocation requests. When malloc buckets is enabled, allocation
requests that fall within a predefined range of block sizes are
processed by malloc buckets. All other requests are processed in the
usual manner by the default allocator.
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Malloc Multiheap -- From section 4.2.6 of Developing and Porting and
C++ Applications on AIX at
http://www.redbooks.ibm.com/redbooks/pdfs/sg245674.pdf:
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Historically, the malloc subsystem was designed for the non-threaded
programming environment. Therefore, there was an single memory pool, or
memory heap, per-process basis. After the evolution of the
multi-threaded programming environment, it was realized that the single
heap does not satisfy the memory allocation requests from
multi-threaded applications, because a single malloc() call from a user
thread can lock the entire malloc subsystem and the other user threads
would be starving; thus, malloc() calls within a process would be
serialized.

By providing multiple heaps, malloc multiheap efficiently supports the
memory allocation requests from multi-threaded applications; thus, the
malloc multiheap has a finer locking mechanism than the single heap
malloc subsystem. The potential performance enhancement is particularly
likely for multi-threaded C++ programs, because these may make use of
the malloc subsystem whenever a constructor or destructor is called.
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Does Linux offer any similar extensions? If so, where can I find
document for them?

Thanks,
Geoff Alexander