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Date: Sat, 4 Feb 2012 17:37:14 +0000
From: Alex Sicamiotis <>
To: <>
Subject: RE: DES with OpenMP

to quote myself:

> In the meanwhile my curiosity has peaked as to why the openMP version is producing ~250 to 300k c/s over the standard non-omp client (4750k c/s vs 4450-4500k c/s). Several things being equal (no-asm for both, icc for both, non-hardware optimizations for both, a value of 1 for des_bs_cpt for both, definite use of just 1 thread for both) there are still 300k in favor of openMP which, normally, it should be slower than the non-omp version. 
> Can you think of *any* other parameters which are tweakable and (may) lead to the +300k gain for the omp version? I want to try various stuff but I don't know what to tweak. My rationale is that if the non-omp version is running with at least the same parameters of the omp version, then the non-omp could be slightly faster than the omp-version (I'm always talking about 1 thread) perhaps exceeding 4.8-4.9m c/s instead of being near the 4.5m mark.

...I was just doing a 1.7.9 jumbo-5 run, it is slightly faster (0.2 - 0.4%) with icc than the 1.7.9 in DES but slower in LM. 

icc -fast -msse2 / make clean linux-x86-64  (des_bs_cpt=1) / test @4ghz - no

1.7.9-j5 omp 1 thread

des: 4770/4482 (+0.42% / + 0.20%)
lm: 49211

1.7.9 omp 1 thread

des: 4750/4473

lm: 54787 (+11.33%)

1.7.9 omp 2 thread

des: 9366/8579

lm: 73654 (+9.98%)

1.7.9-j5 omp 2 thread

des: 9410*/8601* (+0.46% / + 0.25%)

lm: 66972

* breaking the 9.4m/8.6m marks for the first time on two threads.

Is this minor difference in DES (and larger negative impact in LM) down to a different resulting code due to the extra stuff, parameters etc, or are there any underlying changes like altered setting / coding differences between 1.7.9 and j5 regarding the cracking procedure itself?

By the way in both 1.7.9 and jumbo, when I run with omp_num_threads=2, the program runs with a nice set to 0 by default. When threads=1, nice goes to 19. (Bug?)

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