Date: Wed, 10 Mar 2010 10:31:54 -0700 From: RB <aoz.syn@...il.com> To: john-users@...ts.openwall.com Subject: Re: Is JTR MPIrun can be optimized for more cores ? 2010/3/10 Solar Designer <solar@...nwall.com>: >> but is also a clear indicator of the lack of communication between the >> individual processes. > > Is it? Assuming that only the "incremental" mode was in use, any > communication between the processes wouldn't make much of a difference. ... > negative, because removing the hashes has its "cost" too). W.A. > mentioned that the total number of hashes loaded was 2 million, so > removing 8 thousand would really not make a difference. Good point - it's still a variable, but not likely as significant as I'd initially thought it would be. >> Please be aware that the MPI patch by itself induces (as I recall) >> 10-15% overhead in a single-core run. > > Huh? For "incremental" mode, it should have no measurable overhead. This is what my experimentation showed. Whether it's the MPI initialization or something else, the difference between patched and non-patched was statistically significant on my Phenom x4. I'll repeat the tests to get more precise numbers, but it's why I made sure it was optional.
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