I have checked on AMD and that is where I get this issue... -Ashwani -----Original Message----- From: satyaakam goswami [mailto:satyaakam@xxxxxxxxx] Sent: Thursday, May 18, 2006 4:00 PM To: Ashwani Bhat Cc: gcc-help@xxxxxxxxxxx Subject: Re: Help Needed for gcc on Linux x86_64 do you see these performance issue on any specific processors ?? as in Intel or AMD... Satya On 5/18/06, Ashwani Bhat <ashwanib@xxxxxxxxxxx> wrote: > On Linux 64 bit platform, gcc shows poor performance for pow() > function when the first argument is very close to 1. To reproduce the > issue, just create a simple c file case.c > > Contents of case.c > ================== > #include <stdio.h> > #include <math.h> > > int main(){ > double x; > int i; > for( i=1; i<10000; i++ ) { > x = pow( 1.0000000000000002, 1.5 ); > } > printf( "x = %1.30f\n", x ); > } > > then compile it > % gcc -lm -m64 case.c -o case > % ./case > > Notes > 1. gcc option -ffast-math does not help here 2. if compiled with > "-m32" instead of "-m64", then the calculation is fast. > > Can you please help me here .. I have tried it with gcc -v3.2.3, > 3.4.2, 4.1.0. But results are same. > > > Thanks and regards, > ------------------------------ > Ashwani Bhat > /Grid Common Tools Team > ashwanib@xxxxxxxxxxx > ------------------------------------------ >
