On 05/08/2015 09:24 AM, scott wrote:
>>> Yes :-) It's not hard to sample the thermal noise, the problem is how to
>>> sample it billions of times per second with enough resolution to be
>>> useful.
>>
>> Well, no, you typically sample it a few times a second and use that to
>> seed a normal PRNG.
>
> But will that not cause the same problems seen already today with
> unrandomness? If the pixel shader for every pixel gets exactly the same
> random seed value, and just uses a PRNG to modify it, won't you see
> patterns?

My plan was more to have some hardware that seeds a PRNG with a 
truly-random seed and then distributes a *different* random iterate from 
the PRNG to each thread in the bunch. It's awkward to code in software, 
but shouldn't be that hard in hardware...

> Apparently the on-chip thermal noise sampler outputs a stream of bits at
> 3 GHz. I don't know how big the hardware is for that circuit, but it's
> not *that* far away from what you'd need to get a true random number for
> every pixel processed on the GPU.

OK.

>> Jesus, that's next-level. Surely if you don't trust the hardware your OS
>> is running on, it's already game over. (?)
>
> Yes, something like a true RNG in every home home PC seems like
> something the NSA would be extremely interested in.

It's slightly mental that the government of one country can insert spy 
hardware into every computer that can ever exist... Especially given 
that all silicon fabrication is done in countries hostile to America... 
But hey, what do I know?

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