Date: Wed, 29 Aug 2012 11:55:14 -0400 (EDT) From: "Brad Tilley" <brad@...ystems.com> To: john-users@...ts.openwall.com Subject: Re: Questions about compiling for Optimal CPU Performance Hi Magnum, >> My older Intel Celeron CPU lists sse, sse2 and sse3 as supported in >> /proc/cpuinfo, should I make-x86-sse2 or make-x86-native when compiling >> jumbo-6? Or does the difference really matter? > > You should probably use linux-x86-64i. If you run a 32-bit OS, you should > really ask yourself why. You're joking, aren't you? Some CPUs are still 32-bit only or have 64-bit capability, but disable it (such as some Intel Atoms). So when asked why, that is the reason I sometimes use a 32-bit operating system and cannot use a 64-bit OS for those specific CPUs. You can understand that I hope. Not sure why this would be questioned... am I missing something? An inside joke only related to JtR perhaps? >> Also, the Makefile has two >> possibilities for OpenMP... >> >> 1. -fopenmp >> 2. -fopenmp -msse2 >> >> Which one should be uncommented for optimal performance when the CPU >> lists >> multiple sse implementations. For example, should a CPU support sse4, >> would I be limiting performance if I opted for OpenMP with -msse2, or >> not? > > Some 32-bit builds need the latter. For a 64-bit build they produce the > same result. I find the former to work better than the latter on 32-bit systems. Brad
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