Heterogeneous System Architecture
||It has been suggested that HSA Foundation be merged into this article. (Discuss) Proposed since May 2014.|
Heterogeneous System Architecture (HSA) is a type of computer processor architecture that integrates central processing units and graphics processors on the same bus, with shared tasking and memory. The HSA is being developed by the HSA Foundation, which includes (among many others) AMD and ARM. The platform's stated aim is to reduce communication latency between CPUs, GPUs and other compute devices, and make these various devices more compatible from a programmer's perspective,:3 relieving the programmer of the task of planning the moving of data between devices' disjoint memories (as must be done with OpenCL or CUDA).
Heterogeneous computing is widely used in system-on-chip devices, such as tablets, smartphones, and other mobile devices. HSA allows programs to use the graphics processor for floating point calculations without separate memory or scheduling.
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Heterogeneous System Architecture is a set of features that define a system architecture which intends to facilitate the propagation heterogeneous computing, i.e. operation of systems that contain multiples processing units, CPUs, GPUs, DSPs and/or any other type of ASICs. The system architecture allows any accelerator, for instance, graphics processor, to operate at the same processing level as the system's CPU.
Among its main features, HSA defines a unified virtual address space space for compute devices: where GPUs traditionally have their own memory, separate from the main (CPU) memory, it requires these devices to share page tables so that devices can exchange data by sharing pointers. This is to be supported by custom memory management units.:6–7
To render interoperability possible and also to ease various aspects of programming:
- Be ISA-agnostic for both CPUs and accelerators.
- Support high-level programming languages.
So far, the HSA specifications comprehend:
- HSA Intermediate Layer (HSAIL)
- virtual instruction set for parallel programs
- similar to LLVM IR and OpenCL SPIR
- finalized to a specific instruction set by a JIT compiler
- make late decisions on which core(s) should run a task
- explicitly parallel
- supports exceptions, virtual functions and other high-level features
- syscall methods (I/O, printf, etc.)
- debugging support
- HSA memory model
- compatible with C++11, OpenCL, Java and .NET memory models
- relaxed consistency
- designed to support both managed languages (e.g. Java) and unmanaged languages (e.g. C)
- will make it much easier to develop 3rd party compilers for a wide range of heterogeneous products programmed in Fortran, C++, C++ AMP, Java, et al.
- HSA dispatcher and run-time
- designed to enable heterogeneous task queueing: a work queue per core, distribution of work into queues, load balancing by work stealing
- any core can schedule work for any other, including itself
- significant reduction of overhead of scheduling work for a core
Mobile devices are one of the HSA's application areas, in which it yields improved power efficiency.
Some of the HSA-specific features implemented in the hardware need to be supported by the operating system's kernel and by specific device drivers. For example, in July 2014 AMD published a set of 83 patches to be merged into version 3.17 of the Linux kernel mainline, aimed at supporting its Radeon and AMD FirePro graphics cards, and APUs based on so-called Graphics Core Next (GCN). This very first implementation focuses on "Kaveri" or "Berlin" APU and works alongside the existing radeon kernel graphics driver (kgd).
|Wikimedia Commons has media related to Heterogeneous System Architecture.|
- Tarun Iyer (30 April 2013). "AMD Unveils its Heterogeneous Uniform Memory Access (hUMA) Technology". Tom's Hardware.
- George Kyriazis (30 August 2012). Heterogeneous System Architecture: A Technical Review (Report). AMD. http://amd-dev.wpengine.netdna-cdn.com/wordpress/media/2012/10/hsa10.pdf.
- "What is Heterogeneous System Architecture (HSA)?". AMD. Retrieved 23 May 2014.
- Joel Hruska (2013-08-26). "Setting HSAIL: AMD explains the future of CPU/GPU cooperation". ExtremeTech. Ziff Davis.
- "Heterogeneous System Architecture: Purpose and Outlook". gpuscience.com. 2012-11-09. Archived from the original on 2014-02-01. Retrieved 2014-05-24.
- "Heterogeneous system architecture: Multicore image processing using a mix of CPU and GPU elements". Embedded Computing Design. Retrieved 23 May 2014.
- "Kaveri microarchitecture". SemiAccurate. 2014-01-15.
- "AMD Is Exploring A Very Interesting, More-Open Linux Driver Strategy". 2014-03-22. Retrieved 2014-03-23.
- "/drivers/gpu/drm". kernel.org.
- Alex Woodie (26 August 2013). "HSA Foundation Aims to Boost Java’s GPU Prowess". HPCwire.