UPDATE Re: making use of userland dtrace on FreeBSD

[Konstantin Belousov]

On Sat, Dec 29, 2012 at 12:22:57AM +1100, Bruce Evans wrote:
> i386 times on ref10-i386:
> gcc -O2 -o f main.c bar.c foo.c:                         0.81 seconds
> gcc -O2 -o f main.c bar.c foo.c -fno-omit-frame-pointer: 0.81 seconds
> gcc -O2 -o f main.c bar.c foo.c -fomit-frame-pointer     0.83 seconds
>   cc -O2 -o f main.c bar.c foo.c:                         1.11 seconds
>   cc -O2 -o f main.c bar.c foo.c -fno-omit-frame-pointer: 1.11 seconds
>   cc -O2 -o f main.c bar.c foo.c -fomit-frame-pointer     1.11 seconds
> 
> 0.81 seconds is 15.08 cycles/iteration in the inner loop.   0.83 seconds
> is 15.45 cycles/iteration.  1.11 seconds is 20.67 cycles/iteration.
I increased the number of iterations in the main() from 100 to 1000,
and I get 34.1s for -fomit-frame-pointer version vs. 44.1s for -fno-omit
with i7 930 and gcc 4.7.2 -O3. I say it is very significant difference.
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