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Date: Mon, 17 Aug 2015 18:01:00 +0300
From: Solar Designer <>
Subject: Re: FMT_OMP_BAD

On Mon, Aug 17, 2015 at 10:53:06PM +0800, Kai Zhao wrote:
> On my laptop and build with ./configure && make -sj8
> $ OMP_NUM_THREADS=1 ../john -test -form=wpapsk
> Warning: OpenMP is disabled; a non-OpenMP build may be faster
> Benchmarking: wpapsk, WPA/WPA2 PSK [PBKDF2-SHA1 256/256 AVX2 8x]... DONE
> Raw: 3232 c/s real, 3232 c/s virtual
> $ OMP_NUM_THREADS=10 ../john -test -form=wpapsk
> Will run 10 OpenMP threads
> Benchmarking: wpapsk, WPA/WPA2 PSK [PBKDF2-SHA1 256/256 AVX2 8x]...
> (10xOMP) DONE
> Raw: 9346 c/s real, 2038 c/s virtual
> So the wpapsk format should set FAST_FORMATS_OMP and

No.  You shouldn't be setting OMP_NUM_THREADS higher than your logical
CPU count for any sort of benchmarking.  (You may do so for a
stress-test, when trying to trigger a bug.)  Also, your laptop's CPU
almost certainly does not have 8 physical cores (probably it has 4), and
its clock rate likely reduces a lot when you use all 4 cores at once.

wpapsk actually scales very well:

11560/1308 = 8.84

Perfect for this test is 9.39.

8.84/9.39 = 94% of perfect


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