POWER microprocessors

POWER microprocessors. The POWER architecture is a RISC instruction set architecture developed by IBM for its high-performance computing systems. Originating from the pioneering IBM 801 project, the family has evolved through multiple generations, powering everything from IBM RS/6000 workstations to the world's most powerful supercomputers like Summit (supercomputer) and Sierra (supercomputer). Its design philosophy emphasizes raw computational throughput, sophisticated multiprocessing capabilities, and exceptional reliability for enterprise and scientific workloads.

History and development

The lineage of POWER began with the foundational research of the IBM 801 project in the late 1970s, led by computer scientists like John Cocke. This work culminated in the first commercial implementation, the RIOS-1 chipset, which debuted in the IBM RS/6000 series in 1990. A pivotal moment occurred in 1991 with the formation of the AIM alliance between IBM, Apple Inc., and Motorola, which led to the derivation of the PowerPC architecture for personal computers. Subsequent generations, such as the POWER3 which introduced full 64-bit computing, and the POWER4 which pioneered a multicore design, were developed solely by IBM for its servers and supercomputers. Major milestones include the POWER5 with its simultaneous multithreading technology and the POWER7 which excelled in commercial workloads for systems like the IBM Power Systems line.

Architecture and design

The POWER architecture is a superscalar, RISC design known for its rich set of features aimed at performance and scalability. A hallmark is its extensive use of out-of-order execution and aggressive branch prediction to maximize instruction throughput. The architecture has consistently featured a large number of general-purpose registers and floating-point registers to facilitate complex calculations. Key innovations include the integration of the AltiVec single instruction, multiple data (SIMD) unit for vector processing and the implementation of advanced reliability features like Chipkill memory protection. Later generations incorporated simultaneous multithreading and on-chip accelerators for tasks like cryptography and compression, as seen in the POWER9 and POWER10 processors.

Implementations and variants

Numerous distinct processor families have implemented the POWER ISA. Early models like the POWER1 and POWER2 were multi-chip designs, while the POWER3 marked the transition to a single-chip, fully 64-bit microprocessor. The POWER4 was a landmark as the first commercially available multicore processor, integrating two cores on a single die. The POWER5 and POWER6 families further refined simultaneous multithreading and energy efficiency for the IBM System p and IBM System i platforms. The POWER7 series emphasized thread density and memory bandwidth, and the POWER8 introduced support for the OpenPOWER Foundation, enabling broader industry collaboration. The most recent mainstream implementations are the POWER9, which powers the Summit (supercomputer), and the POWER10, announced in 2020.

Performance and applications

POWER processors are engineered for extreme performance in enterprise and technical computing. They have long dominated in commercial OLTP workloads on IBM Db2 and SAP platforms, as well as in memory-intensive applications like the IBM Watson system. In scientific computing, their high memory bandwidth and strong floating-point performance made them the processor of choice for landmark supercomputers such as the ASCI White, Roadrunner (supercomputer), and the CORAL systems Summit (supercomputer) and Sierra (supercomputer). The architecture is also foundational to many cloud computing offerings from IBM Cloud and other members of the OpenPOWER Foundation, providing infrastructure for artificial intelligence and big data analytics.

Software and ecosystem

The primary operating system for POWER-based systems is IBM AIX, a proprietary Unix environment, alongside the IBM i operating system for integrated business systems. Since the advent of the OpenPOWER Foundation, support for open-source software has expanded significantly, with major Linux distributions like Red Hat Enterprise Linux and SUSE Linux Enterprise Server offering full support. Key development tools include the GNU Compiler Collection, the IBM XL C/C++ Compilers, and the OpenJDK Java runtime. The ecosystem is bolstered by enterprise software from partners like SAP, Oracle Corporation, and VMware, and by firmware standards like the Open Firmware boot system used in many designs.