john-users - Re: Re: JTR and os X macintel

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Date: Thu, 5 Oct 2006 10:32:06 +0400
From: Solar Designer <solar@...nwall.com>
To: john-users@...ts.openwall.com
Subject: Re:  Re: JTR and os X macintel

On Thu, Oct 05, 2006 at 05:53:47AM +0000, -. -PhanTom-. - wrote:
> Oh well, AMD has been known as the king of 
> Floating Point Operations in the past, they will be again... I guess

This has nothing to do with JtR since it does not use floating point
operations at all.

> > > I was under the impression that the high speeds on Macs were due to the 
> > > G4 and G5 cpus and that the OS had very little to do with it...?
> > 
> > Correct.
> 
> Does this apply to Linux vs Windows as well?

Yes - there should be almost no performance difference for JtR on Linux
vs. Windows (except for Windows 9x/ME and older).

> As far as I could tell, latest version of JTR would theoretically yield 
> higher speeds on linux64 on an AMD64 cpu compared to windows...

I have to be guessing as to where you derived this conclusion from.  We
had a discussion in here some months ago where you wanted to make a
64-bit build of JtR on Windows - and that is not currently supported.
So you could not see whether your CPU would yield better performance
when running the x86-64 16-register SSE2 code vs. the plain x86
8-register SSE2 code.  I suggested that you try on a Linux/x86-64
system.  I did not imply that the 16-register version would be faster
for you - although it might be.

> However, I did test this and saw no higher speeds on Linux64 compared to 
> windows32.... could be related to compilation though..not sure... 

It is entirely possible that the 16-register version is not any faster
on your CPU.  In fact, it may even be a little bit slower, such as
because of the extra instruction prefixes.  Either way, the difference
should be within 10% - anything beyond that would be abnormal.

Please note that SSE is 128-bit (at least from the application's point
of view) regardless of whether you build for 32-bit or 64-bit.

-- 
Alexander Peslyak <solar at openwall.com>
GPG key ID: 5B341F15  fp: B3FB 63F4 D7A3 BCCC 6F6E  FC55 A2FC 027C 5B34 1F15
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