Archives Discussions

[greenflops]

Hi,

I am currently benchmarking HSA configuration compared to Catalyst drivers with SHOC. I can't see any visible differences in terms of computation speed for both configurations on A10-7850K... Why? I thought that HSA could bring some gain? I cant see where I am wrong.

Regards,

[jedwards · Accepted solution]

The SHOC benchmark is an OpenCL application, and is written to take advantage of GPU hardware directly. HSA is an architecture designed to allow direct access to GPU hardware, but that greatly simplifies programmatic access when compared to higher level programming models, like OpenCL. This is especially true for memory access operations on the host and in kernels due to the coherent memory model of HSA. It is a common misunderstanding that HSA will "make things go faster" than OpenCL for every workload. It is true the HSA should provide performance gains over OpenCL for some workloads, but that is not the primary goal of HSA. Both programming models take advantage of the compute power of the GPU, and the SHOC samples were specifically written to exhibit the capabilities of OpenCL; it is not surprising that performance will be comparable.

[greenflops]

Yes, SHOC is an opencl benchmark. How can I easily translate some of thoses programs into HSA?. When runing clinfo I only have the CPU cores enabled, seems that the GPUs are not used (almost 0% load with radeontop...)

[jtrudeau]

From what I understand, at this time the HSA standard is designed for APUs. It currently is not designed to take advantage of discrete GPUs. That may come in the future. Here at AMD we are very interested in that functionality, but it is an industry standard, not an AMD standard. So we'll see what happens.

[greenflops]

I don't use discrete GPU

[jedwards]

First, the HSA standard targets more than APUs, but the AMD implementation currently only targets APU devices, not discrete GPUs.

Second, for an OpenCL benchmark to take advantage of HSA an OpenCL implementation must be provided that uses the HSA architecture for GPU access. Currently the AMD implementation of OpenCL doesn't support HSA, although this may change in the future.

If you want to port OpenCL applications directly to the HSA interface consult the following GitHub links regarding HSA to get started:

HSAFoundation/HSA-Docs-AMD · GitHub

HSAFoundation/CLOC · GitHub

HSAFoundation/HSA-Runtime-AMD · GitHub

HSAFoundation/HSAIL-HLC-Stable · GitHub

[greenflops]

Yes, I agree. I don't use discrete GPU. Only APU A10-7850K. I have the same hardware platform as specified in HSA Platforms & Installation · HSAFoundation/HSA-Docs-AMD Wiki · GitHub (7850K, Asus A88X-Pro, drivers, etc...)

The only tool I found to monitor the GPU (from APU) is radeotop (I couldn't use amdconfig with this driver)

Spectre has disapear, GPUs are not available anymore from cl interface...

[jedwards]

From what I can tell you have the hardware required to run using the HSA software stack. If you have installed the HSA driver set correctly (currently only supported on Ubuntu 14.04 and Fedora 21 Linux systems) you should be able to launch HSA applications using the HSA runtime on the A10-7850K APU. Note that these drivers don't support the standard AMD OpenCL implementation, so clinfo will not expose the Spectre device. In this environment, OpenCL will most likely fallback to the CPU device. Running the SHOC benchmark will not provide meaningful results.

[greenflops]

Yes, this is OK, Both kfd_check_installation script and sample/vector_copy validation are OK.(Even on Ubuntu 14.10, with the HSA kernel)