Re: Memory Manager

From: Thorsten Engler [NexusDB] (thorsten.englerNO_at_SPAMnexusdb.com)
Date: 01/09/05 

Date: Sun, 9 Jan 2005 20:35:50 +1000

> Another benefit of 64bits systems: they'll make move-on-realloc
> practically a thing of the past with a good memory manager. :)

NexusMM3, to be released shortly after NexusDB2 (in which it will be
included) allocates large allocations (>64KB) in a way to allows to grow
(reallocate) the allocation without having to copy the contents of the
allocation to a new memory location and without wasting address space by
pre-reserving more address space then is needed for the initial allocation.
The address of the allocated block of memory may change as a result of the
reallocate, but neither is additional physical memory required (other
MemoryManager implementations have to allocate the new, larger block of
memory and copy the contents before freeing the old block) nor is any memory
contents actually copied nor is the CPU cache flushed out (which can happen
with other MMs as a result of having to copy the memory contents). The time
required for a realloc remains constant independent of current allocation
size (other memory managers have to copy the contents, which will take
longer the larger the current allocation is). And all this on any normal
32bit system by adding a single new line to the project uses list. :)

Cheers,
Thorsten Engler [NexusMM Architect]

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