Date: Wed, 5 Sep 2012 07:33:20 +0400 From: Solar Designer <solar@...nwall.com> To: john-dev@...ts.openwall.com Subject: Re: memory usage (was: [john-users] JTR against 135 millions MD5 hashes) On Tue, Sep 04, 2012 at 05:06:38AM -0400, jfoug@....net wrote: > Do the builds drop to binary align=1 on intel boxes? We probably > should, or at least allow a compile define to get this, in case it > causes a slight runtime slowdown. Even for salts, I think we should > drop to align=1 on systems allowing non-aligned access, and fix any > formats which core due to actually having alignment issues (such as SIMD > access). The requires aligned systems (like sparc) but even there, it > might be better to have the default be 1, and fix any format with > issues. Possibly it would be better with more than 1 default value. Currently, mem_alloc_tiny() has: #if ARCH_ALLOWS_UNALIGNED if (mem_saving_level > 2) align = MEM_ALIGN_NONE; #endif So alignments are only disabled at the heaviest memory saving level, along with other performance-killing. Maybe we should adjust this - what happens at what memory saving level - although it'd be good to do some performance testing first. I don't like the idea of disabling the alignments at compile time. Alexander
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