bear wrote:
> What supprise me a lot is the code with initialization(io==1) is
> much faster than without initialization(io!=1). The initialization
> code should takes some time and it should slow down the program.
> But the result confuse me. Why?
Oddly, I see the opposite:
./basic 50 1024 0
CPU time: 4.190000 sec
./basic 50 1024 1
CPU time: 9.930000 sec
compiled 3.3.6, -O0, Pentium II, Fedora Core 3.
My best guess would be that in the uninitialized case, since you don't
initialise s0-s3 at all, you're performing computation on the random data
left in your allocated memory and these are slower than the simple
calculations based on real values. But I can't reproduce that here, and in
my tests zeroing s0-s3 after allocating them makes negligible difference.
Rup.
