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Date: Thu, 19 Apr 2012 15:38:32 -0300
From: Claudio André <claudioandre.br@...il.com>
To: john-dev@...ts.openwall.com
Subject: [Off-topic] Experiments!
Hi, i'm not sure what are you guys expecting about results in (my)
OpenCL implementation.
Anyway, i can say i saw a lot of crazy things while playing with AMD
compiler. I put Ivan's opinion below. Lukas said something some time
ago. Somehow, i can even put the compiler in loop, something even i
(myself) think is hard to believe.
From: http://www.golubev.com/blog/?p=223
"AMD OpenCL compiler producing ineffective code, it simply locks up
on complex kernels, it doesn't know how to use hardware capabilities
of GPUs properly, some kernels (after "optimizations" done by
compiler) simply producing incorrect results."
Unbelievable? Trust him.
The code in git now is better suited for the new SI boards [1]. (Almost)
The opposite of mine 6770 GPU card [2].
Not sure about your plans for the source code or if you want to keep it.
Anyway, i will keep trying it and/or give advices to anyone who wants to
try it.
---
[1] See /section 4.16 in Optimization Guidelines for Southern Islands
GPUs [////link
<http://developer.amd.com/sdks/amdappsdk/assets/AMD_Accelerated_Parallel_Processing_OpenCL_Programming_Guide.pdf>//,
visited in 04/19/2012//]. / For example: "Vectorization is no longer
needed, nor desirable. If your code used to combine work-items in order
to get better VLIW use, this is no longer required." Seems more likely
NVIDIA hardware.
[2] In my VLIW hardware, in order to make it works in "full speed"i'll
need to vectorize more. Despite i'm not confident in good results, i
think combine work-items is my best shot for my 6770.
---
To clarify: my motivation was to show that is possible to run crypt
SHA-512 on cheap GPU, and crack a real set of data (some random
passwords). And it is done now, and i have to thank John community to
give me the good software i can work with.
My problem is solved. Good GPU hardware is not affordable here. I'm
afraid i'm not going to be much active further.
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