Heterogeneous computing

Heterogeneous computing systems refer to electronic systems that use a variety of different types of computational units. A computational unit could be a general-purpose processor (GPP), a special-purpose processor (i.e. digital signal processor (DSP) or graphics processing unit (GPU)), a co-processor, or custom acceleration logic (application-specific integrated circuit (ASIC) or field-programmable gate array (FPGA)). In general, a heterogeneous computing platform consists of processors with different instruction set architectures (ISAs). The demand for increased heterogeneity in computing systems is partially due to the need for high-performance, highly reactive systems that interact with other environments (audio/video systems, control systems, networked applications, etc.). In the past, huge advances in technology and frequency scaling allowed the majority of computer applications to increase in performance without requiring structural changes or custom hardware acceleration. While these advances continue, their effect on modern applications is not as dramatic as other obstacles such as the memory-wall and power-wall come into play.12 Now, with these additional constraints, the primary method of gaining extra performance out of computing systems is to introduce additional specialized resources, thus making a computing system heterogeneous.34 This allows a designer to use multiple types of processing elements, each able to perform the tasks that it is best suited for.5 The addition of extra, independent computing resources necessarily allows most heterogeneous systems to be considered parallel computing, or multi-core (computing) systems. Another term sometimes seen for this type of computing is "hybrid computing".6 Hybrid-core computing is a form of heterogeneous computing wherein asymmetric computational units coexist with a "commodity" processor.
The level of heterogeneity in modern computing systems gradually rises as increases in chip area and further scaling of fabrication technologies allows for formerly discrete components to become integrated parts of a system-on-chip, or SoC. As an example, many new processors now include built-in logic for interfacing with other devices (SATA, PCI, Ethernet, RFID, Radios, UARTs, and Memory Controllers), as well as programmable functional units and hardware accelerators (GPUs, Encryption Co-processors, programmable network processors, A/V encoders/decoders, etc.).