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Date: Tue, 2 Jun 2015 10:37:27 +0800
From: Lei Zhang <zhanglei.april@...il.com>
To: john-dev@...ts.openwall.com
Subject: Re: Lei's weekly report #5

> On Jun 2, 2015, at 9:52 AM, Solar Designer <solar@...nwall.com <mailto:solar@...nwall.com>> wrote:
> 
> On Tue, Jun 02, 2015 at 08:44:56AM +0800, Lei Zhang wrote:
>> Accomplishments:
>> - experiment with the newly interleaved SHA256 & SHA512
>> - use AVX512/MIC's scatter instruction in SHA1, SHA256 & SHA512
> 
> I think it's the first time I hear about the second one of these tasks -
> "use AVX512/MIC's scatter instruction in SHA1, SHA256 & SHA512" - can
> you please post a separate report on this?  Explain the idea, where it
> fits in the code, and what results you obtained.  Thanks!

Magnum and I were discussing this topic on GitHub.
https://github.com/magnumripper/JohnTheRipper/issues/1220 <https://github.com/magnumripper/JohnTheRipper/issues/1220>

Sometimes it's just more convenient to discuss "smaller" topics on GitHub, and I forget to bring them to john-dev.


>> Priorities:
>> - determine the optimal interleaving factors for MIC
>> - find out formats where OMP_NUM_THREADS isn't optimal for MIC
>> - now that I know how to correctly build OpenSSL for MIC, try to compare JtR's performance on MIC built with OpenSSL vs LibreSSL
> 
> I think more importantly than all of those you listed, you need to start
> reviewing and profiling the generated assembly code.  Right now, it is
> unclear why there's often a slowdown when going from 1x to 2x
> interleaving, even if in some cases there's a speedup at higher
> interleaving factors.  You need to find this out.  Until you do, you're
> unnecessarily walking blindfolded.

OK.
But what do you mean by "reviewing the assembly code"? What exactly am I supposed to investigate in the assembly?


Lei


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