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Date: Thu, 28 Mar 2013 09:45:13 +0100
From: magnum <john.magnum@...hmail.com>
To: john-dev@...ts.openwall.com
Subject: Re: MPI-openCL build; fast hashes are faster!!

On 27 Mar, 2013, at 22:54 , Sayantan Datta <std2048@...il.com> wrote:
> OpenCL-MPI build using openmpi results in some of the fast hashes to speed up by 1.5-3x without any extra modification  e.g. raw-md4,raw-md5,raw-sha1 ,xsha512 and des. I haven't tested all hashes but most of them works fine except the slow hashes which causes asic hangs most of the time with anything more than 1 thread feeding the GPU. 

Please note that the benchmark output from MPI runs is unreliable in this case - for legacy reasons it's just the fastest individual figure multipled by number of nodes. Normally this is OK but in this case you'll likely get an inflated value.

We could change this to a true sum of individual speeds, I'm not sure why the original MPI patch had it this way. According to the README-mpi, it's "in interest of cooperating with other patches" and that might actually mean it was simplified merely to reduce merge conflicts (this was long before git).

In the mean time, try this for a reliable figure:

$ echo aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa > test.in
$ ../run/john -fo:raw-md4-opencl test.in -inc -nolog -min-len=8 -max-len=8 -max-run=3

If using MPI, manually do the sum of speeds reported. Increase the -max-run for more accurate figures if needed.

magnum

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