Date: Tue, 4 Sep 2012 07:47:05 +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) Jim - On Mon, Sep 03, 2012 at 11:12:18PM -0400, jfoug@....net wrote: > On Mon, Sep 3, 2012 at 8:49 PM, Solar Designer wrote: > >I did not realize that there were wasteful allocations in prepare() > >and valid(). Weren't they temporary? > > They were done using alloc_memory_tiny. Now, I simply use static > buffers. When raw hashes were being used, and a few other cases, there > could be one or more of these type allocations, which are very similar > to memory leaks, when done on temp transient data. Did you include fixes for this in the fixes branch? If not yet, can you do that? I guess those changes are non-invasive. > >Another potential source of memory usage reduction are the alignments. > >For raw MD5 hashes, a 4-byte alignment should suffice (they're 4x4 > >bytes), yet we were using 8-byte alignment on 64-bit builds. > > Very good point. I had not even thought of things like these new > alignment requirements. I really think for most formats, 4 is the > correct alignment, due to dereference of an arch_word_32 in some of the > lookup functions. > > I do not have time to fully address all of the issues brought up in your > reply, but will try to look more in depth at this tomorrow afternoon. I think that for now our priority should be specifying proper alignments for each format's binary and salt (in bleeding). Thanks, Alexander
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