Re: [boost] [random] new threefry random engine

Subject: Re: [boost] [random] new threefry random engine
From: Beman Dawes (bdawes_at_[hidden])
Date: 2014-04-20 12:30:37

On Sun, Apr 20, 2014 at 7:17 AM, Thijs van den Berg <thijs_at_[hidden]> wrote:

> ...
> // loop version
> threefry4x64_08_64:  10.2318 nsec/loop =  19.13350 CPU cycles
> threefry4x64_13_64:  14.3048 nsec/loop =  26.75000 CPU cycles
> threefry4x64_20_64:  22.6186 nsec/loop =  42.29680 CPU cycles
> threefry4x64_99_64: 100.0110 nsec/loop = 187.02200 CPU cycles
>
> // 40x manual unrolled version
> threefry4x64_08_64:   3.7386 nsec/loop =   6.99118 CPU cycles
> threefry4x64_13_64:   5.1223 nsec/loop =   9.57870 CPU cycles
> threefry4x64_20_64:   7.3078 nsec/loop =  13.66560 CPU cycles
> threefry4x64_99_64:  29.3599 nsec/loop =  54.90300 CPU cycles
>
> You may want to ask others to run the tests with various CPU's and
compilers. Making optimization decisions based on a single platform can be
quite misleading.

Remember Knuth's famous quote: "*premature optimization is the root of all
evil*":-)

--Beman