Re: incredible slowdown switching to 64 bit g++
On Nov 25, 8:27 am, nandor.sie...@gmail.com wrote:
Just A Quick question: does the program do the same thing on
a 64bit machine as on a 32bit machine? has testing shown
that for the same input you get the same output?
There are small differences in the values of doubles but I
guess that's not unexpected.
Not really. Both the 64 bit machine and the 32 bit one are
probably using IEEE doubles. Even on a 32 bit machine, a double
is normally 64 bits.
Compiling in 64 bit mode will often result some reduction in
speed, because of larger program size, and thus poorer locality.
I can't imagine this representing more than a difference of
about 10 or 20 percent, however, and I would expect it usually
to be a lot less.
Have you profiled the two cases, to see which functions have
become significantly slower?
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James Kanze (GABI Software) email:james.kanze@gmail.com
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