Date: Thu, 10 May 2012 03:55:25 +0530 From: SAYANTAN DATTA <std2048@...il.com> To: john-dev@...ts.openwall.com Subject: Re: Sayantan: Weekly Report #3 Wow. 20% is excessive and not expected. We need to figure out why this > is so - or maybe it is not (that is, part of the speedup might be from > some side-effect, not directly from the OpenMP parallelization). > > You compute two MD4 hashes on host per MSCash2 hash, correct? At 80k c/s, > this means you compute 160k MD4s per second, and you say this corresponds > to over 20% of total running time (you say you saved 20% by > parallelizing this). Thus, the total speed would be less than 800k MD4/s - > sounds too low even for the somewhat non-optimal and non-vectorized code > that we have there. For the raw-md4 format in a "make generic" build > (thus also non-vectorized), I am getting between 5M and 6M c/s on this CPU > (also on one core, indeed). (For vectorized code, it's more like 30M c/s > on one core.) So there's a factor of 7 difference here, which we don't > have an explanation for. > > Well it's not MD4 alone which consumes cpu time. A deeper look into the code suggests that conversion from byte to hexstring consumes significant amount of time, nearly around 90% of total CPU time. Thus the remaining 10% of cpu time is consumed by the md4 and other stuffs. Sayantan. Content of type "text/html" skipped
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