Re: Memory,allocator,performance in C/C++ compilers

"ed mckenzie" <eem12@cornell.edu> writes:


> Am I missing something? Are there other things influencing allocator
> performance besides block size, number of blocks, and allocation
> pattern?


Yes the algorithm used for example. Depending on the algorithm some
allocators are better for small blocks and others are better for
larger blocks.


> Or is VC++'s memory allocator just slower than the other >
> compilers?


Since I haven't analyzed yet I can't tell you if it is really slower.
But my experience with allocators on other platforms( HP-UX) shows
that there are significant differences in allocator performance. For
example I found that the HP-UX is rather slow compared to for example
Doug Leas allocator (http://g.oswego.edu/) . As far as I remember it
was a factor of 4 or 5.


> Interestingly, there's a third-party allocator for VC++ (UltraHeap)
> that claims similar performance gains over the standard 6.0 RTL
> allocator. Is there a heap benchmark that could measure this sort of
> thing with more accuracy and completeness than a simple test
> program?


No idea.


I can recommend you Doug Leas allocator it's free and I think it works
on Windows too. The last time I tested gnu-malloc it was slower when
this allocator (at least on my platform HP-UX).


Another thing you should consider is implementing an allocation scheme
yourself for the most important datastructures.


Markus
--
Markus Kohler mailto:markus_kohler@hp.com

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