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Date: Mon, 7 Jan 2013 07:31:13 +0400
From: Solar Designer <solar@...nwall.com>
To: john-dev@...ts.openwall.com
Subject: Re: des-opencl

On Mon, Jan 07, 2013 at 04:03:23AM +0400, Solar Designer wrote:
> http://www.reddit.com/r/crypto/comments/162ufx/research_project_opencl_bitslice_des_bruteforce/

Another curious detail about mysterymath's implementation is that it
obviously exceeds instruction cache, yet is reasonably fast on GCN.
We should try that too as it avoids pointer indirection and reduces
register pressure due to hard-coding key bit indices (no key schedule
array needed anymore).  Lukas reported very poor performance on 5850,
though.

While at it, I found this discussion thread:

http://devgurus.amd.com/thread/158867

with some info on GCN ISA level optimizations - how scalar vs. vector
instructions get scheduled, etc.  With kernels exceeding instruction
cache size, the recommendation is to schedule more wavefronts to help
hide instruction fetch latency.

Alexander

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