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Date: Sun, 18 Mar 2012 07:33:09 +0400
From: Solar Designer <solar@...nwall.com>
To: john-dev@...ts.openwall.com
Subject: Re: AMD Bulldozer and XOP

On Fri, Mar 16, 2012 at 01:45:23AM +0400, Solar Designer wrote:
> On Thu, Mar 15, 2012 at 11:24:07PM +0200, Milen Rangelov wrote:
> > So 256-bit XOP is slower than 128-bit one?
> 
> According to benchmarks that were sent to me before I got a Bulldozer of
> my own, yes - about twice slower per bit (four times slower per
> instruction).  (I haven't tested 256-bit XOP on my own FX-8120 yet.
> Will do so a bit later.)

I've just tried this myself.  256-bit XOP is slower than 128-bit, but
not by that much.  This is on FX-8120 at its rated frequencies.

Benchmarking: Traditional DES [128/128 BS XOP-16]... (8xOMP) DONE
Many salts:     17190K c/s real, 2144K c/s virtual
Only one salt:  12782K c/s real, 1591K c/s virtual

Benchmarking: Traditional DES [128/128 BS AVX-16]... (8xOMP) DONE
Many salts:     14818K c/s real, 1856K c/s virtual
Only one salt:  11016K c/s real, 1381K c/s virtual

Benchmarking: Traditional DES [128/128 BS SSE2-16]... (8xOMP) DONE
Many salts:     14688K c/s real, 1829K c/s virtual
Only one salt:  11162K c/s real, 1391K c/s virtual

Benchmarking: Traditional DES [256/256 BS XOP-16]... (8xOMP) DONE
Many salts:     14659K c/s real, 1832K c/s virtual
Only one salt:  10851K c/s real, 1365K c/s virtual

Benchmarking: Traditional DES [256/256 BS AVX-16]... (8xOMP) DONE
Many salts:     13263K c/s real, 1651K c/s virtual
Only one salt:  10067K c/s real, 1255K c/s virtual

I've also tried various mixed instructions (such as AVX and ALU) and
even things like:

OMP_NUM_THREADS=4 GOMP_CPU_AFFINITY='0 2 4 6' ./john-xop256 -te -fo=des &
OMP_NUM_THREADS=4 GOMP_CPU_AFFINITY='1 3 5 7' ./john-native -te -fo=des &

but none of these resulted in a better cumulative speed.  Simply doing
128-bit XOP and only it from all 8 threads works best so far.

Alexander

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