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Date: Sat, 12 Sep 2015 16:53:42 +0800
From: Lei Zhang <zhanglei.april@...il.com>
To: john-dev@...ts.openwall.com
Subject: Re: SHA-1 H()

On Sep 11, 2015, at 12:26 AM, Solar Designer <solar@...nwall.com> wrote:
> 
>> On Power (8xOMP, bound to a single core)
>> 
>> [before]
>> MD4:	28248 c/s real, 3531 c/s virtual
>> MD5:	19980 c/s real, 2497 c/s virtual
>> SHA1:	10593 c/s real, 1322 c/s virtual
>> 
>> [after]
>> MD4:	31207 c/s real, 3882 c/s virtual
>> MD5:	19980 c/s real, 2489 c/s virtual
>> SHA1:	11273 c/s real, 1409 c/s virtual
>> 
>> On Power (1xOMP)
>> 
>> [before]
>> MD4:	13398 c/s real, 13398 c/s virtual
>> MD5:	10626 c/s real, 10626 c/s virtual
>> SHA1:	8533 c/s real, 8533 c/s virtual
>> 
>> [after]
>> MD4:	14628 c/s real, 14628 c/s virtual
>> MD5:	10935 c/s real, 10935 c/s virtual
>> SHA1:	8947 c/s real, 8947 c/s virtual
>> 
>> At least there's no performance drop on Power. BTW, It looks Power's SMT performance is not very impressive.
> 
> Why, a 2x+ speedup compared to 1 thread is very good.  It's similar to
> or even better than what we're seeing with interleaving on x86.

I don't really get it...

On my laptop, where each core supports 2 hardware threads, running 2 threads gets a 2x speedup compared to 1 thread on the same core. OTOH, each Power8 core supports up to 8 hardware threads, so I'd expect a higher speedup than just 2x.


Lei

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