Re: [boost] [random] parallel random number generators

Subject: Re: [boost] [random] parallel random number generators
From: Mathias Gaunard (mathias.gaunard_at_[hidden])
Date: 2012-01-26 14:06:19

On 01/25/2012 08:55 PM, John Salmon wrote:

> A couple of weeks ago, I asked if there was interest in a parallel RNG in
> boost.
> Here's a pointer to my original post:.
>
> http://lists.boost.org/Archives/boost/2012/01/189293.php
>
> Our paper on parallel random number generators is here:
> http://dl.acm.org/citation.cfm?doid=2063405
> also available at
> http://www.thesalmons.org/john/random123/papers/random123sc11.pdf
>
> Source (non-boost) is available here:
> http://deshawresearch.com/resources_random123.html
>
> And software that might be a starting point for a boost contribution is
> here:
> http://thesalmons.org/john/random123/prf_boost/prf_boost.zip
>
> Feedback is appreciated.

The above code seems quite more readable than the one from the 
deshawresearch website, but also a bit shorter.
Does it do everything the deshawresearch does?

I see you're using inline asm for mulq on GCC, but you don't use __umulh 
for MSVC.
I can't see any hit for _mm_clmulepi64_si128 (which I assume would be 
useful).

Your cpuid code won't work with gcc -m32 -fPIC, and also doesn't appear 
to take care of register trashing properly.
I also don't really think the code should do any cpuid check at all, 
since emitting AESNI instructions requires -maes, and whenever you use 
-maes the compiler is free to emit AESNI instructions whenever it wants.

 From what I see, you only use SSE instructions if AESNI is available. 
Is that really desirable?

There is a library proposed for Boost that abstracts SIMD instructions 
and scalar built-ins (Boost.SIMD), it might be interesting to use it / 
extend it to take care of all the platform-specific bits.

In any case I think this would be a very interesting contribution to 
Boost and the open-source community in general.