Introduction to Khronos SYCL
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SYCL (Khronos SYCL) is an open standard for single-source heterogeneous programming that uses C++ templates. It aims to provide a more native C++ interface for OpenCL-like programming while retaining compatibility with OpenCL. The key aspects covered are the SYCL programming model which supports most C++11/14 features, its single-source approach across devices, and memory model including shared virtual memory. However, it currently lacks official implementations and support is mainly through the triSYCL library.
Introduction to Khronos SYCL
- 1. C++ Single-Source Heterogeneous Programming for OpenCL Khronos SYCL Bekket McClane @ Advanced Programming Language, Jenq-Kuen Lee 2016 Spring, NTHU
- 2. Syllabus ❖ Heterogeneous Computing By OpenCL ❖ Introducing to SYCL ❖ SYCL Internals ❖ Programming Model ❖ Execution Model ❖ Memory Model ❖ Summary
- 3. OpenCL Host Program (C/C++, …) OpenCL Kernel (OpenCL C) Dispatch Propertied Device Compiler Accelerated Devices (GPU, DSP…) SPIR-V Compiler Source Propertied SPIR-V Compiler SPIR-V
- 4. OpenCL the Bad Part 1
- 5. OpenCL the Bad Part 1 Kernel Code
- 6. OpenCL the Bad Part 1 Kernel Code Host Code
- 7. OpenCL the Bad Part 2
- 8. OpenCL the Bad Part 3 OPENCL (CPU) FALLBACK IMPLEMENTATION?
- 9. OpenCL the Bad Part 3 OPENCL (CPU) FALLBACK IMPLEMENTATION?
- 10. SYCL Start Up
- 11. SYCL Start Up Single Source
- 12. SYCL Start Up Single Source Multiple Implementations
- 13. SYCL Programming Model ❖ All C++14 features. Except Runtime Type Information(RTTI) ❖ Exception Handling ❖ C++11 lambda ❖ C++11 variadic templates, template aliases ❖ C++11 rvalue reference ❖ C++11 std::function, std::string, std::vector
- 14. SYCL Data Parallel 101
- 15. SYCL Data Parallel With Workgroup
- 16. SYCL Execution Model ❖ Platforms ❖ Devices ❖ Command Queue ❖ Command Group ❖ Kernel ❖ Context ❖ Program Terms
- 17. SYCL Execution Model ❖ Platforms ❖ Devices ❖ Command Queue ❖ Command Group ❖ Kernel ❖ Context ❖ Program Terms Same as OpenCL
- 18. SYCL Command Group ❖ Group of OpenCL commands ❖ Commands in group are executed in-order ❖ The smallest scheduling unit ❖ Different command groups may executed out-of-order
- 20. SYCL Kernel
- 21. SYCL Kernel
- 22. SYCL Device-side Enqueue ❖ Has same behavior as that in OpenCL 2.x ❖ Sub-kernel has separated command queue ❖ Use out-of-order command queue like OpenCL (No command group?) ❖ Use events to manage command orders ❖ No concrete examples so far
- 23. SYCL Memory Model ❖ Global, Constant, Local, Private just like OpenCL ❖ cl::sycl::accessor ❖ cl::sycl::buffer : Unified handle to many kinds of memory ❖ Allow Shared Virtual Memory ❖ Allow atomic access
- 26. Powerful Accessor Template • Read • Write • Read/Write Atomic Related* SVM Related
- 27. SYCL Shared Virtual Memory
- 28. SYCL Shared Virtual Memory SVM buffer allocation
- 29. SYCL Shared Virtual Memory Host Access SVM buffer allocation
- 30. SYCL Shared Virtual Memory Host Access SVM buffer allocation Device Access
- 31. SYCL the Good Part - Memory ❖ Both cl::sycl::buffer and cl::sycl::accessor encapsulate underlying memory into a “handle” ❖ The “handle” provides a flexible way to manipulate data ❖ Adoption of C++ template reserves spaces for features in the future
- 32. Summary
- 33. triSYCL ❖ Use Boost library(http://www.boost.org) to simulate ❖ The only implementation(and header files) seen so far ❖ Latest SYCL 2.2! ❖ Need to be compiled with C++14 ! (-std=c++14) https://github.com/amd/triSYCL
- 34. SYCL the Missing Part ❖ Where are the (official)header files? ❖ Little examples ❖ SYCL to SPIR-V compiler? ❖ Still a young project
- 35. SYCL in a Nutshell ❖ Single source. Neat syntax ❖ All the shiny C++ features ❖ Easy-implement fallbacks ❖ Follow the version(steps) of OpenCL ❖ No real devices(platforms) available for playing so far ❖ *NOT intended to replace OpenCL (Still needs exist OpenCL drivers/implementations)
- 36. Thank You Q & A