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Date: Tue, 13 Aug 2013 11:33:34 +0530
From: Sayantan Datta <std2048@...il.com>
To: john-dev@...ts.openwall.com
Subject: Re: key-length for mask mode.

On Tue, Aug 13, 2013 at 10:51 AM, Solar Designer <solar@...nwall.com> wrote:

> That's good news, but have you reviewed myrice's PG-test and
> experimented with it by now (with a variety of loaded hash counts
> ranging from one to millions)?  If not yet, please stop all other work
> and do that now!  It is wrong to abandon previous attempts without even
> using the opportunity to learn from them (both what was done right and
> what was done wrong).  And yes, myrice's code achieved a similar speed,
> including with more hashes - IIRC, we were testing with 1M and 10M, as
> well as with a few thousand, and the speed somehow varied between
> invocations, sometimes being above 3000M c/s and sometimes below.  (This
> is twice slower than hashcat's, though.)
>

I have tested myrice PG-test branch without any tweaks:

OpenCL platform 0: AMD Accelerated Parallel Processing, 2 device(s).
Using device 0: Tahiti
Local work size (LWS) 128, Global work size (GWS) 65536
Loaded 12906 password hashes with no different salts (Raw MD5 [OpenCL])
end self test
guesses: 0  time: 0:00:00:04 0.00% (3)  c/s: 11518G  trying: ph0370 -
47192769
guesses: 0  time: 0:00:00:08 0.00% (3)  c/s: 14075G  trying: drap02 - bms100
guesses: 0  time: 0:00:00:10 0.00% (3)  c/s: 14586G  trying: cenie105 -
mcdo1140
guesses: 0  time: 0:00:00:13 0.00% (3)  c/s: 13778G  trying: shlva - hsets
guesses: 0  time: 0:00:00:15 0.00% (3)  c/s: 14159G  trying: js7712 - rgli
guesses: 0  time: 0:00:00:17 0.00% (3)  c/s: 14449G  trying: bl746t - paybol
guesses: 0  time: 0:00:00:19 0.00% (3)  c/s: 14679G  trying: sith2 - s23h1
guesses: 0  time: 0:00:00:21 0.00% (3)  c/s: 14865G  trying: sl3adu - bdbmme

Myrice's kernel is spilling into scrach registers which might be the reason
for lower performance. Most likely you had tested it with
a different driver. One thing I noticed in myrice's kernel was that it was
using too many kernel arguments. Increasing kernel args increases VGPR
usage count which in turn results in register spilling.

I am trying to introduce a hash table but that again increases VGPR count.
I would try to minimize VGPR usage so that I can introduce a few more
kernel arguments.

 Also can you post a list of 10M hashes?

Regards,
Sayantan

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