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Date: Wed, 26 Jun 2013 13:48:58 +0400
From: Solar Designer <>
Subject: Re: new dev box wishes (was: Contest)

magnum, Sayantan, all -

On Mon, May 27, 2013 at 08:54:52AM +0530, Sayantan Datta wrote:
> Have we considered Titan ?

I am considering it now, because I think this is something less likely
to be present in individual JtR developers' computers.  Another reason
(and a reason to pay the ~$300 premium over GTX 780) is that it offers a
lot better performance at double precision floating-point.  This is
totally irrelevant to JtR (at least so far), but the tentative plan is
to offer accounts on our new dev box to the larger Open Source
community (not only JtR devs), and someone might find this useful.

Here's a question: do we want the Titan at stock clocks or one of those
vendor-overclocked models (can be up to 10% faster)?  In other words, do
we want our benchmark results to represent stock Titan, or do we want
better speeds (and we'd have to mention the weird clock rates each time
we publish benchmarks obtained on our Titan)?  Unfortunately, I am not
aware of an existing tool to adjust clock rates on NVIDIA cards from
Linux (such tools exist for Windows), so we'd be stuck at vendor's.

> Can we use the two GPUs on a 7990 separately ?


> If not we shouldn't be replacing 7970 on bull either.

bull will stay as it is, at least for now.

The tentative config for the new dev box is:

CPU: 4770K

Motherboard: one of those with four PCIe 16x slots - but we'd probably
use at most 3, so that we don't burn it.  The PCIe lane counts might be
8-8-4-4 or 8-8-8-8 (the latter costs a lot more, though).

PCIe cards:
Xeon Phi 5110P

We'll need to install CentOS 6 (RHEL6) or openSUSE (SLES) as these are
the only ones officially supported by Intel MPSS (needed to access Xeon
Phi).  It is possible to install MPSS on Ubuntu or another distro with
some effort, but I'd rather not deviate from what's officially supported.

Ideally, we'd be able to access the GPU portion of 4770K as well, by
choosing it as the primary video output via BIOS setup.  (Otherwise it's
disabled as soon as a discrete video card is installed.)

So we'll need to try to install a fine mix of drivers and SDKs, and
indeed this might fail.  Not to mention likely overheating when all of
the devices are under full load.  If things start to fall apart, we'll
have to setup yet another machine (perhaps with FX-8350 for a change)
and move perhaps the 7990 card to there.

If this does work, though, it'd be nice to be able to access 5 kinds of
devices on the same machine, ideally including via OpenCL (although for
Xeon Phi we'll need to focus on programming it more directly, such as in
C with intrinsics and OpenMP).


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