Date: Sat, 11 Aug 2012 01:59:14 +0200 From: Lukas Odzioba <lukas.odzioba@...il.com> To: john-dev@...ts.openwall.com Subject: Re: Current -fixes GPU formats vs TS 2012/8/11 Solar Designer <solar@...nwall.com>: > In trying to trigger the problem without running xsha512-cuda first, I > added: > > cudaMemset(cuda_hash, -1, PWSAFE_OUT_SIZE); > > right after: > > cudaMalloc(&cuda_hash, PWSAFE_OUT_SIZE); > > This didn't make any difference in triggering the problem (nor in > preventing it), but surprisingly it provided a 3% speedup (approx. > 106k c/s to 109k c/s on bull's GTX 570). > > A memset with 0 also provides some speedup (a slightly smaller speedup? > not sure). > > Any idea why? This might be a clue. I wasn't able to reproduce this bug that way (running xsha first) but it I was able to get 100% self test fails during ./john -test=0. This speedup is weird what is c/s, 3% seems to be more than error dispersion. I have no idea what is the source of this speedup. Maybe some powersaving mechanisms inside cuda impelentation or device itself. On gtx470 I get 466->470 after adding memset. Lukas
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