It all depends on the sysetm size. Larger system sizes will scale better in general. <div class="gmail_quote">On Jan 24, 2008 9:12 AM, cavallo <<a href="mailto:lcav...@unisa.it">lcav...@unisa.it</a>> wrote: <blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;"> Dear All, I just started to work with cp2k, and I would like to know the speedup I can expect with cp2k on dual-core em64t and opteron machines. I tested a simple job on an em64t. Running on 2 cpus the speedup is 1.07 instead of 2. Going up to 4 cpus the speedup is 1.28 instead of 4. Teo Laino was kind enough to test my input on a Cray, and he got a speedup of 1.50 on 2 cpus, and 2.79 on 4 cpus, which is definitely better. Since this is my first cp2k installation, I would like to know if the speedup I got is in line with other people experience on em64t and opterons multicore machines (I hope not), or I have to work to compile a better executable (in the case any tip is very wellcome). There's no problem of memory or hd access, since two serial jobs running simultaneously are not slowed down. So far, I compiled cp2k on a fedora 7, intel 10.0.025, intel-mkl libraries, and gcc compiled fftw3 and mpich2. Thanks, Luigi Reston, VA 443-567-8328 (C) 410-278-2692 (O)