I will just tell You about my experiences:
- allmost all code of benchmark in Ego library is inlined (remove_stone is not)
- function pointer are usually inefficient, because jump prediction works poorly
- when I introduced a parameter to simple_playout::run: function
pointer that replaced play_one and always put address of play_one
there, then the code was slightly faster.
I have *no idea* why it was so.
- and most important: KISS
Lukasz
On 2/16/07, Darren Cook <[EMAIL PROTECTED]> wrote:
>> trouble. Also, the alternative is usually function pointers which have
>> atleast 50 times the overhead of a function object. Correct me if I'm
>> wrong.
>>
> function objects really cannot be 50 times more efficient as function
> pointer are rather efficient with very little overhead.
With well-designed code, function objects ("functors") should be
compiled inline, and have zero overhead. Function pointers are never
inlined (unless modern compilers are getting *really* clever), so they
always have some overhead. Functors are therefore divide-by-zero-times
more efficient (I don't know where Nick got the 50 times figure from :-).
(If the functor is large enough to not be inlined then it is execution
time that dominates and function call overhead is not important.)
Using functors might cause more code, so less code fits in cache. I
don't know how that affects overall performance.
Darren
_______________________________________________
computer-go mailing list
computer-go@computer-go.org
http://www.computer-go.org/mailman/listinfo/computer-go/
_______________________________________________
computer-go mailing list
computer-go@computer-go.org
http://www.computer-go.org/mailman/listinfo/computer-go/
