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Message-ID: <20150905041749.GA24684@openwall.com>
Date: Sat, 5 Sep 2015 07:17:49 +0300
From: Solar Designer <solar@...nwall.com>
To: john-dev@...ts.openwall.com
Subject: Re: MD5 on XOP, NEON, AltiVec
On Sat, Sep 05, 2015 at 05:25:16AM +0300, Solar Designer wrote:
> Here's what we had last year:
>
> Benchmarking: md5crypt, crypt(3) $1$ [MD5 128/128 XOP 8x]... (8xOMP) DONE
> Raw: 201472 c/s real, 25152 c/s virtual
>
> Here's what we have now:
>
> Benchmarking: md5crypt, crypt(3) $1$ [MD5 128/128 XOP 4x2]... (8xOMP) DONE
> Raw: 150272 c/s real, 18784 c/s virtual
I sort of found it: somehow the code handling SSEi_FLAT_OUT, when
compiled in, changes the stack frame layout in such a way that
performance drops. I wasn't yet able to tell why it drops. The
offsets look properly aligned to me either way.
With SSEi_FLAT_OUT support #if 0'ed out, I get:
Benchmarking: md5crypt, crypt(3) $1$ [MD5 128/128 XOP 4x2]... (8xOMP) DONE
Raw: 223232 c/s real, 27869 c/s virtual
And that's not even with the MD5_I change yet (haven't tried it yet).
For raw-md5, performance stays the same. For raw-md4, commenting out
its SSEi_FLAT_OUT results in very slight regression, and its speed is
unexpectedly low either way (about the same as raw-md5's, whereas it
should be faster). So there's yet another performance issue for us to
investigate for raw-md4 (and maybe other MD4-based formats).
As to commenting out SSEi_FLAT_OUT support for both of these, as far as
I can tell we are not using it currently. (We're using it for SHA*.)
Alexander
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