Re: P4 optimized Debian GNU/Linux?
On Fri, Feb 27, 2004 at 08:40:28AM +0000, Adam Majer wrote:
> start_time = time();
> for( int i=0; i<10000000; i++ ) // I forget how many 0 I had exactly
> sin ( i / 324.34444 );
> end_time = time();
> printf( "Diff: %d\n", end_time - start_time );
>
> When I run the program with no optimization -O0, I got some numbers that
> looked about the same for both machines. Then I compiled with
> -march=pentium-4 and -march=athlon-xp and -O6, and surprise, surprise,
> the P4 had a speed *decrease*!! It slowed down from something like 23
I did enough performance work at Microsoft to know that your test is
meaningless. Just because you know X at level Y doesn't imply a thing
about your knowledge at level 10Y, good or bad. The program might get
slower, or faster, or crash.
Some people call this "nonlinear." A perf expert described it to me as
more accurately: stochastic.
So you can draw no conclusions whatsoever from your test.
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