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Message-ID: <57980.85.178.106.100.1212943209.squirrel@www.jpberlin.de>
Date: Sun, 8 Jun 2008 18:40:09 +0200 (CEST)
From: sebastian.rother@...erlin.de
To: john-users@...ts.openwall.com
Subject: Re: How to chose computer for John?
>> (For instance E2160),
A E2140 is even cheaper and just a slice slower. :D
> That's a good choice.
>
>> or AMD Sempron64 3000+ or AMD Athlon 64 4000?
>
> These are a lot slower, especially at DES-based hashes supported by JtR
> natively (that is, not with contributed patches).
>
> All of these are low-end, though. If you can afford a more expensive
> CPU and don't mind higher power consumption, and you really intend to be
> running JtR a lot and care about its performance a lot (maybe you should
> not, actually), I'd recommend going for a quad-core Core 2 based
> processor.
*cut*
Quad core? And what do the other 3 cores do in the meanwhile or did JtR
gained a good SMP-capable implementation I ma missed?
You claim a Q6600 is 2.5 times faster if all cores are used so I'd like to
know how you do use ALL cores for a single session with JtR.
I wont argue or piss you off Solar but right now it's not realy possible
to use more then one core or may I missed something? :-/
> Of course, you will need to run one instances of JtR per core manually.
> This means two instances on E2160 or four instances on Q6600.
Yeah that's what I mean. But running 4 instances does not mean it is
"faster" at all. The only way I can imagine such a method is by splitting
the password file/4 and run each part in a single and seperated instance.
Wouldn't it be possible to may splitt JtR into a "daemoN" and serval
clients wich do communicate via IPC? So you could propably use all Cores.
One "JtR"-Client for each core. I am unsure if this works for john but it
came into my mind right now. :)
>> * For John the Ripper, what is better in general, Pentium or AMD?
>
> There's no general answer. Specific CPUs and specific hash types need
> to be compared. Right now, my advice is to go for Core 2 based CPUs,
> some of which are now confusingly branded a "Pentium" again. However,
> most other CPUs also branded a "Pentium", such as Pentium D, are a lot
> slower and consume a lot more power (and please don't be misled by their
> higher clock rates).
The new INTEL CPUs may get 256Bit SSE-Engines wich may could improve the
situation again (like the 64Bit to 128Bit SSE engines).
But that's something Solar may should know a lot better.
Also I'd like to know if SSE3/4/5 may improve something compared to SSE2.
> You must be referring to JtR change log entries comparing versions 1.7,
> 1.7.1, and 1.7.2. You should not care about this. You're interested in
> overall performance of current versions on different CPUs, not in
> changes in performance between versions (you would not be running the
> older versions anyway). Besides, newer CPUs are now available anyway,
> so the changes that were initially of benefit on AMD processors only
> are now of even greater benefit for Intel Core 2 (which was not around
> at the time).
> No, the version of Windows (except for Windows 9x) makes no difference
> for JtR performance. However, you may consider 64-bit versions of both
> Linux and Windows, and making a 64-bit build of John. This results in a
> 10% performance improvement for DES-based hashes supported by John
> natively. (Not because of the 64-bitness itself - John uses 128-bit
> SSE2 vectors either way - but because of availability of 16 registers in
> 64-bit mode as opposed to just 8 in 32-bit mode.)
That affected AMD64 CPUs some years ago.
Is that statement still true Solar?
I remember that we talked about AMD some time ago and that I pointed this
out. But I am unsure if modern CPUs have still such limitations.
Maybe this could get noticed in a FAQ or so in case the situation changes
but somebody is using JtR on a "old" AMD64 (3600+ or something like this).
> Also, if you go for a
> quad-core CPU, you'll want a suitable Windows license that will let you
> make use of all "CPUs". I'm not familiar with Windows licensing, but I
> think that XP used to be licensed for 1-2 CPUs only "by default", and
> you needed a more expensive license for more CPUs. I don't know about
> Vista. Perhaps someone else will comment on this.
As far as I know Vista supports just up to 8 Cores wich may hit the market
this year already. But I could be wrong.
To be "sure" you should use the Premium-foo.
Kind regards,
Sebastian
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