D and GPGPU

[luminousone via Digitalmars-d]

On Friday, 20 February 2015 at 10:05:34 UTC, francesco.cattoglio 
wrote:
> On Wednesday, 18 February 2015 at 18:14:19 UTC, luminousone 
> wrote:
>> HSA does work with discrete gpu's and not just the embedded 
>> stuff, And I believe that HSA can be used to accelerate OpenCL 
>> 2.0, via copyless cache coherent memory access.
>
> Unless I'm mistaken, it will more like the opposite: HSA will 
> use OpenCL 2.0 as a backend to do that kind of "copyless" GPGPU 
> acceleration.

HSAIL does not depend on opencl, and it supports more then 
copyless gpgpu acceleration, as it said, it has been access to 
virtual memory, including the program stack.

HSA defines changes to the MMU, IOMMU, cpu cache coherency 
protocol, a new bytecode(HSAIL), a software stack built around 
llvm and its own backend in the gpu device driver.

OpenCL 2.0, generally obtains its copyless accel from remapping 
the gpu memory into system memory, not from direct access to 
virtual memory, Intel supports a form of copyless accel via this 
remapping system.

The major difference between the two systems, is that HSA can 
access any arbitrary location in memory, where as OpenCL must 
still rely on the pointers being mapped for use.

HSA has for example have complete access to runtime type 
reflection, vtable pointers, you could have a linked list or a 
tree that is allocated arbitrarily in memory.