Warp wrote:
> "J�r�me M. Berger" <jeb### [at] freefr> wrote:
>>         By simple curiosity, I've also added Warp's implementation of 
Isaac 
>> and here is the result (see attached code):
> 
>>  > g++ -O3 -lm -o random random.cc IsaacRand.cc
> 
>   I suggest adding -march=native in order for gcc to fully optimize i
t for
> your platform. It might make a big difference, especially with this typ
e
> of code.
	It doesn't change anything here. Remember that the gcc shipped with 
most 32-bits linux distros is configured to generate code for the 
original Pentium! In this case, forcing the compiler to optimize for 
your machine is usually a big win. On 64-bits platforms however, 
there is not that much difference between the first generation 
Athlon64 and the current generation.

>   (Also -lm is probably not needed. At least I don't need it here.)
> 
	I originally didn't put it, but I added it because it was needed 
for the C version. Now that the code is compiled as C++, you're 
right it's not needed any more.

>>  > ./random
>> Empty loop:          0ms
>> Kiss64 (int):     6623ms
>> Kiss64 (dbl):     5003ms
>> Alvo (floor):    21539ms
>> Alvo (cast):     14608ms
>> Alvo (tmp+cast): 14664ms
>> Isaac:           10540ms
> 
>   I tried running the program on my Pentium4 (with g++ -O3 -march=nat
ive)
> and got the following results:
> 
> Empty loop:          0ms
> Kiss64 (int):     2669ms
> Kiss64 (dbl):     2643ms
> Alvo (floor):     2098ms
> Alvo (cast):      1767ms
> Alvo (tmp+cast):  1766ms
> Isaac:             690ms
> 
>   The speed seems to be pretty dependant on the CPU type being used...
> 
	So it seems...

>   Out of curiosity, I also tried adding -mfpmath=sse to the compiler 
options,
> and the results changed a bit:
> 
> Empty loop:          0ms
> Kiss64 (int):     2687ms
> Kiss64 (dbl):     2640ms
> Alvo (floor):     2424ms
> Alvo (cast):      1294ms
> Alvo (tmp+cast):  1335ms
> Isaac:             685ms
> 


-- 
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