PGI User Forum

lqcd_chris · Joined: 05 Jul 2007 Posts: 2

Hello:

I have compiled some physics code using fftw with pg... v. 6.2-3 and with icc/ifort v. 9.1 to compare performance.

For intel, I used the -fast option, and found the fftw3.1.2 part runs in 1 minute, which is a little less than what I get using gcc.

Then, I compiled with the Portland Group compiler (both the fftw libraries and my program, of course), and the same fftw takes 10 minutes!

After trying a few different sets of options including just -fast -tp amd64, I found the best one is -O0 -tp amd64, for which the fftw part still takes 3.5 minutes!

I am quite sure there is something funny going on, but I have no idea what it is. Has anyone here seen something like this before?

Thanks,
Chris

mkcolg · Posted: Fri Jul 06, 2007 8:31 am Post subject:

Hi Chris,

lqcd_chris · Joined: 05 Jul 2007 Posts: 2

Hi, Mat

Thanks for your quick reply. I have been away for a while, and just found it. I don't think sharing the code is a problem, but I have to talk to a few people first.