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Date: Thu, 13 Nov 2014 01:35:32 +0300
From: Solar Designer <>
Subject: Re: Xeon Phi support?

On Wed, Nov 12, 2014 at 09:39:07PM +0100, magnum wrote:
> On 2014-11-12 08:17, Royce Williams wrote:
> >Given the recent sub-$200 pricing for the Xeon Phi 3151P, and the
> >relative scarcity of inexpensive ZTEX boards :-) , what are the
> >potential and likely performance, and level of effort required to use
> >Intel Phi boards with John the Ripper? Just looking for some rough
> >approximations.
> Using OpenCL is pretty straightforward - as with any other device you 
> just need to have drivers for it and JtR will accept it.
> Solar/Openwall has a Xeon Phi 5110P in a dev box. The (admittedly old) 
> drivers currently installed on that box are *awful*, they fail compiling 
> many kernels and others segfault when running. This driver is worse than 
> Apple's OpenCL drivers for nvidia/AMD two years ago, which would 
> otherwise easily hold the world record in crappiness.
> Right now I'm not interested in playing with the Phi for that reason alone.

As you're aware, OpenCL is a wrong way to use Xeon Phi, at least
currently.  Besides the poor state of OpenCL support for it, why buy the
normally expensive Xeon Phi and then use it as if it were a cheap GPU?

Perhaps it'd help you appreciate the good things about Xeon Phi if you
temporarily forget the existence of OpenCL support for it?

We need to update JtR's CPU "formats" to use Xeon Phi intrinsics.  I did
that for bitslice DES (unreleased; I should release now that there's
some interest in Xeon Phi), and the rest of the team may easily do it
for other SIMD'able hash types.  For a handful of them, such as SunMD5
and scrypt, things might be slightly interesting performance-wise.

We need to support cross-compiling of jumbo for Xeon Phi, or/and to add
support for OpenMP offload.  In my bitslice DES experiments, I was
compiling 1.8.0 with my patches, not jumbo.  To compile jumbo, we first
need to cross-compile some libraries.


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