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
------------------------------------------
