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From: Darren Cook (darren_at_[hidden])
Date: 2003-05-08 18:23:34

>> A 2-3% timing difference probably isn't reliably repeatable in real code.

My timing tests were interleaved as I swapped in various algorithms and
recompiled and the time differences were consistent. I gave ranges not
averages to give a feel for the "experimental error".

> I'm not sure, though, if this negates your point, Beman. Something that
> gives a 2-3% speedup for one Boost user might not be worth any level of
> obfuscation unless we can prove it provides a similar speedup for other
> Boost uses.

Just to avoid confusion for people joining this thread halfway, the 2-3%
speedup was in my code; I wasn't proposing obfuscating any boost library.

My point was that I got this speed-up by overriding operator new/delete with
one-liners in just a single class (of course I chose the class I new from
profiling was making heaviest use of new/delete):

void* operator new(std::size_t sz){
   return boost::detail::quick_allocator<T>::alloc(sz);

void operator delete(void *p,std::size_t sz){

where T is the name of my class. That is so easy it is practically free,
like using -O3 instead of -O2.

> In our project, a 3% speed increase is considered a cause for celebration.
> ....
> - sped up JavaScript iBench by 70% by using a better sort algorithm and
> reducing the number of UString allocations

How did you celebrate that one then? :-)


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