[linux-audio-dev] soft synth as a plugin

[Tim Goetze]

Stefan Nitschke wrote:

>>
>>erm, sorry, but why not use pointers?
>>
>
>Just out of couriosity i made a benchmark test between C and C++ with
>gcc3. I dont have a clue abour x86 assembler so i made a measurement.
>
>Here is the C code (not realy useful as real code would have a need for a
>struct and a pointer operation to call the filter() function) and the
>C++ code.
>Both "simulate" a low pass filter and are compiled with:
>  gcc -O2 -march=pentium -o filter filter.xx
[...]
>C++ with member:
>real    0m11.847s
>user    0m11.850s
>sys     0m0.000s
>
>C++ with new() and pointer:
>real    0m12.337s
>user    0m12.330s
>sys     0m0.000s
>
>C:
>real    0m16.673s
>user    0m16.670s
>sys     0m0.000s

my interpretations:

c++ sans new() might be quicker because of better cache 
locality (the class instance is just a local stack var,
while with new() it is somewhere on the heap in another
memory page).

i don't think reference and pointer access make the 
difference, after all the internal representation should
be the same. granted, new() is a lot slower than a local 
class on the stack but your code only allocates once.

have you checked whether the optimizer inlined the C
function call? it looks like it didn't.

tim