Anyone has any experiences on power counters on Intel processors(intel performance counter management library) or GPUs, which type of CPUs and GPUs support such counters, how accurate are these counters? Do such counters needs special motherboard?
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I am trying to estimate the power consumption of my OpenCL Kernel running on AMD Radeon RX Vega GPU. is there a way to access the power consumption through OpenCL directly?
I tried using profilers but could not find one that supports amd GPUs or opencl. so I want to do it through programming if that's possible
I now managed to access the average power consumption of the GPU (provided in mW) through the rocm_smi library.
this is a little tricky and more of an estimate because it is hard to call while the kernel is launched. However, if the kernel's runtime is long enough, I can run rocm_smi from command line and get the average power consumption during the kernel's launch.
Hi I'm working on developing an application, which involves working on shared data between GPU and CPU.
I know I can do atomic operation GPU and CPU separately. And also I don't want to use event synchronized between CPU and GPU.
Is there any way/command so that I can do atomic operation on shared data between CPU and integrated GPU in OpenCL?
It's possible but there are preconditions. You'll need a device supporting OpenCL 2.0 or higher (Intel, AMD and ARM all have such devices, i dunno about Nvidia).
To get started, look here,here and here.
If the (discrete) GPU has its own video RAM, I have to copy my data from RAM to VRAM to be able to use them. But if the GPU is integrated with the CPU (e.g. AMD Ryzen) and shares the memory, do I still have to make copies, or can they both alternatively access the same memory block?
It is possible to avoid copying in case of integrated graphics, but this feature is platform specific, and it may work differently for different vendors.
How to Increase Performance by Minimizing Buffer Copies on Intel® Processor Graphics article describes how to achieve this for Intel hardware:
To create zero copy buffers, do one of the following:
Use CL_MEM_ALLOC_HOST_PTR and let the runtime handle creating a zero copy allocation buffer for you
If you already have the data and want to load the data into an OpenCL buffer object, then use CL_MEM_USE_HOST_PTR with a buffer allocated at a 4096 byte boundary (aligned to a page and cache line boundary) and a total size that is a multiple of 64 bytes (cache line size).
When reading or writing data to these buffers from the host, use clEnqueueMapBuffer(), operate on the buffer, then call clEnqueueUnmapMemObject().
GPU and CPU memory sharing ?
GPU have multiple cores without control unit but the CPU controls the GPU through control unit. dedicated GPU have its own DRAM=VRAM=GRAM faster then integrated RAM. when we say integrated GPU its mean that GPU placed on same chip with CPU, and CPU & GPU used same RAM memory (shared memory ).
References to other similar Q&As:
GPU - System memory mapping
Data sharing between CPU and GPU on modern x86 hardware with OpenCL or other GPGPU framework
Are coprocessors like Intel Xeon-Phi supposed to be utilized much like the GPUs, so that one should offload a large amount of blocks executing a single kernel, so that only the overall throughput the coprocessor handles results in a speed up, OR offloading independent threads (tasks) will increase the efficiency as well?
The Xeon Phi requires a large degree of both functional parallelism (different threads) and vector parallelism (SIMD). Since the cores are essentially enhanced Pentium processors, serial code runs slowly. This will change somewhat with the next generation as it'll use faster and more modern cores. The current Xeon Phi also suffers from the I/O bottleneck as does any coprocessor, having to communicate over a PCIe bus.
So though you could offload a kernel to every processor and exploit the 512-bit vectorization (similar to a GPGPU), you can also separate your code into many different functional blocks (i.e. different codes/kernels) and run them on different sets of Intel Xeon Phi cores. Again, the different blocks of code must also exploit the 512-bit SIMD vectors.
The Xeon Phi also operates as a native processor, so you can access other resources by mounting NFS directory trees, communication between cards and other processors in the cluster using TCP/IP, using MPI, etc. Note that this is not 'offload' but native execution. But the PCIe bus is still a significant bottle neck limiting I/O.
To summarize,
You can us an offload model similar to that used by GPGPUs,
The Xeon Phi itself also can support functional parallelism (more than one kernel) but each kernel must also exploit the 512-bit SIMD.
You can also write native code and use MPI, treating the Xeon Phi as a conventional (non-offload) node (always remembering the PCIe I/O bottleneck)
I am interested to try out GPU programming. One thing not clear to me is, what hardware do I need? Is it right any PC with graphics card is good? I have very little knowledge of GPU programming, so the starting learning curve is best not steep. If I have to make a lot of hacks just in order to run some tutorial because my hardware is not good enough, I'd rather to buy a new hardware.
I have a retired PC (~10 year old) installed with Ubuntu Linux, I am not sure what graphics card it has, must be some old one.
I am also planning to buy a new sub-$500 desktop which to my casual research normally has AMD Radeon 7x or Nvidia GT 6x graphics card. I assume any new PC is good enough for the programming learning.
Anyway any suggestion is appreciated.
If you want to use CUDA, you'll need a GPU from NVidia, and their site explains the compute capabilities of their different products.
If you want to learn OpenCL, you can start right now with an OpenCL implementation that has a CPU back-end. The basics of writing OpenCL code targeting CPUs or GPUs is the same, and they differ mainly in performance tuning.
For GPU programming, any AMD or NVidia GPU made in the past several years will have some degree of OpenCL support, though there have been some new features introduced with newer generations that can't be easily emulated for older generations.
Intel's integrated GPUs in Ivy Bridge and later support OpenCL, but Intel only provides a GPU-capable OpenCL implementation for Windows, not Linux.
Also be aware that there is a huge difference between a mid-range and high-end GPU in terms of compute capabilities, especially where double-precision arithmetic is supported. Some low-end GPUs don't support double-precision at all, and mid-range GPUs often perform double-precision arithmetic 24 times slower than single-precision. When you want to do a lot of double-precision calculations, it's absolutely worth it to get a compute-oriented GPU (Radeon 7900 series or GeForce Titan and up).
If you want a low-end system with a non-trivial GPU power, you best bet at the moment is probably to get a system built around an AMD APU.