[Pkg-opencl-devel] opencl-icd selection

[Rebecca N. Palmer]

This platform order is only meant to provide a sane default for 
applications that just want "a working, and preferably fast, device"; 
those that need something more specific will still need to do their own 
choosing or require manual intervention.

> amd (fglrx) vs nvidia?
I put mesa (=AMD hardware) in the middle because it can be either a 
discrete or an integrated GPU, with the intention of getting the right 
order for most machines.

The obvious way to estimate speed from clinfo parameters (compute units 
* native vector width * max clock) doesn't work: it says my CPU 
(4*4float*3.2GHz) should be nearly the same speed as my GPU 
(16*4float*1GHz), but it is actually 8-16x slower.

> (Yes, I have a couple of machines where I have discrete GPUs from both
> vendors installed).
Can you test:
-does mesa-opencl-icd+beignet still break things (#768185) when mesa has 
hardware, and if so is mesa also broken by this
-which order (CPU or GPU first) amd-opencl-icd returns its devices in

> Maybe this could be implemented at the distribution level
Debian packaging can apply arbitrary source changes (debian/patches), so 
if we want to make some or all of this Debian-specific, we can do so 
without involving environment variables.