AMD's HSA Run-Time Library Is Now Open-Source

[CrystalGamma]

http://lwn.net/Articles/605153/
"AMD GPUs designed for use with HSA (Sea Islands and up) share some hardware
functionality between HSA compute and regular gfx/compute (memory,
interrupts, registers), while other functionality has been added
specifically for HSA compute (hw scheduler for virtualized compute rings).
All shared hardware is owned by the radeon graphics driver, and an interface
between kfd and kgd allows the kfd to make use of those shared resources,
while HSA-specific functionality is managed directly by kfd by submitting
packets into an HSA-specific command queue (the "HIQ")."

Thanks, that helped a lot.

[pixo]

My first impression on HSA was that APU like Kaveri or other speciali build HW that has HUMA will be needed.
It`s good to know that not the case. ( Yay for me as i have r7 260 and r9 290 and according to mesa page they are both Sea Island )
But still how big is the performance hit while using discret cards?
Is the Intell platform supported and if yes what tech does it need? (i have both vt-d and vt-x)

[bridgman]

It's more of a feature hit than a performance hit. Without an IOMMUv2 block you lose the ability to have the GPU transparently use pageable system memory, so the code using the HSA runtime will need to make API calls to allocate memory and make the memory accessible by the GPU.

There are really three HW scenarios :

1. internal GPU on APU (GPU has fast access to pageable system memory)
2. discrete GPU on APU (GPU accesses pageable system memory via PCIE bus)
3. discrete GPU on CPU without IOMMUv2 (no access to pageable system memory)

[vein]

I meant R9 285 chipsets and newer will benefit from this. I'm not up-to-date with IGP's but I think its an older architecture so that will probably not be supported.

Yeah, sorry. I was writing from my phone. I ment to quote from ElectricPrism but I must have missclicked. My bad.

Anyway, I didn't know R9 285 actually had HSA support . Nice. But I think I'll still wait for the R9 300 series...since it seems to become a really nice release (Rumors about 20nm tech. and exclusive HBM memory etc etc)

[sascha]

So the R9 285 is the only supported GPU right now?

[bridgman]

One more time...

There are two different drivers being confused here, amdkfd (the HSA kernel driver) and amdgpu (the new graphics kernel driver).

The amdkfd (HSA) driver currently supports Kaveri and additional (CI and higher) hardware support will be added.

The amdgpu (graphics) driver will officially support Tonga (R9 285) and up, although internal development work was done on CI hardware.

... so for purposes of *this* thread (about userspace HSA runtime library) support is for Kaveri, not R9 285.

[drSeehas]

confused

... The amdkfd (HSA) driver currently supports Kaveri and additional (CI and higher) hardware support will be added.
... so for purposes of *this* thread (about userspace HSA runtime library) support is for Kaveri, not R9 285.

???
But R9 285 is higher than Sea Islands (CI).

[bridgman]

Yes, but (a) I was responding to sascha's comment that "R9 285 is the only supported GPU right now" (which is not true) and (b) R9 285 is not supported today.

[odedgabbay]

Yes, but (a) I was responding to sascha's comment that "R9 285 is the only supported GPU right now" (which is not true) and (b) R9 285 is not supported today.

To make it absolutely clear, amdkfd currently supports only APUs, and the only APU which is HSA-capable at the moment is Kaveri.
We are planning to support discrete GPUs as well (e.g. R9 285) but this would take some time.
And, as John said, amdkfd has nothing to do with the graphic support, which is given by either the radeon driver (for CI and older) and the new, yet unpublished, amdgpu driver (for VI and up). Those drivers will of course support both APUs and discrete GPUs.
Bottom line, to run HSA, you need both a graphic driver (radeon or amdgpu in the future) and amdkfd installed and running on your system.
I hope this clears things.

Oded

[nanonyme]

So do apps need changes to benefit of amdkfd? Stupid question most likely