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Date: Thu, 20 Aug 2015 03:37:33 +0200
From: magnum <john.magnum@...hmail.com>
To: john-dev@...ts.openwall.com
Subject: Re: Formats using non-SIMD SHA2 implementations

On 2015-08-19 17:52, Lei Zhang wrote:
> Anyway, I applied the optimizations we discussed so far to 7z, including sorting passwords by length (Jim's idea) and using double-buffer (magnum's idea). I compared the performance of the optimized SIMD code, my previous naive SIMD code and the scalar code. See the figures below. (Specs: AVX2, 8-HT)
>
> OpenMP disabled:
>
> [scalar]
> Raw:	12.7 c/s real, 12.7 c/s virtual
> [naive SIMD]
> Raw:	48.2 c/s real, 48.2 c/s virtual
> [optimized SIMD]
> Raw:	48.6 c/s real, 48.6 c/s virtual
>
> OpenMP enabled:
>
> [scalar]
> Raw:	49.1 c/s real, 6.4 c/s virtual
> [naive SIMD]
> Raw:	72.3 c/s real, 9.3 c/s virtual
> [optimized SIMD]
> Raw:	201 c/s real, 26.7 c/s virtual
>
> As you can see, single-threaded performance of the optimized SIMD code shows no benefit, but multi-threaded performance is much better. The code becomes much more unreadable than before, but I think it's worth it :)

Will you wrap this up in a PR before "pencils down"? I can't see it in 
your repo at all. BTW I presume you've seen PR #1682? Merging that with 
your code should be trivial either way we do it.

magnum

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