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Date: Mon, 14 Sep 2015 20:44:07 +0300
From: Solar Designer <solar@...nwall.com>
To: john-dev@...ts.openwall.com
Subject: Re: md5crypt mmxput*()

On Wed, Sep 09, 2015 at 03:00:01AM +0200, magnum wrote:
> On 2015-09-08 16:18, Solar Designer wrote:
> >Benchmarking: md5crypt, crypt(3) $1$ [MD5 128/128 XOP 4x2]... (8xOMP) DONE
> >Raw:    231680 c/s real, 28923 c/s virtual
> 
> Code size, eh? This reminded me there is a "#pragma GCC optimize 3" in 
> that file that I always found slightly dubious. We should verify how 
> each format reacts to dropping that.
> 
> Quick test for now, on bull; Enabled the switch for XOP, dropped that 
> pragma:
> 
> Benchmarking: md5crypt, crypt(3) $1$ [MD5 128/128 XOP 4x2]... (8xOMP) DONE
> Raw:    233472 c/s real, 29184 c/s virtual

I think you never committed this change?  Since you also confirmed it
helping on AVX2, I think you should, unless you know of a regression.

> Then again, how about -O2 and *not* using switch?
> 
> Benchmarking: md5crypt, crypt(3) $1$ [MD5 128/128 XOP 4x2]... (8xOMP) DONE
> Raw:    232960 c/s real, 29120 c/s virtual
> 
> OK, that's inbetween. So before having tested any other format or arch, 
> the pragma should go and the switch should be use for XOP too.

It seems so, and this makes sense.

> Apparently Jim added that pragma in 2013 while (I think) adding SHA-2, 
> likely because Gosney's original code had it. I will do some testing!

Have you done more testing since?

Alexander

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