Randal C. Swanberg

Advanced virtualization capabilities of POWER5 systems

IBM POWER5TM systems combine enhancements in the IBM PowerPCTM processor architecture with greatly enhanced firmware to significantly increase the virtualization capabilities of IBM POWERTM servers. The POWER hypervisor, the basis of the IBM Virtualization EngineTM technologies on POWER5 systems, delivers leading-edge mainframe virtualization technologies to the UNIX® marketplace. In addition to being able to create computing-intensive partitions with dedicated resources (processors, memory, and I/O adapters), customers can harness idle processor capacity to configure micropartitions with virtualized resources in order to consolidate many AIXTM, i5/OSTM, and Linux® servers onto a single platform. The POWER hypervisor provides support for virtualized processors, an IEEE virtual local area network (VLAN)- compatible virtual Ethernet switch, virtual small computer system interface (VSCSI) adapters, and virtual consoles. Many of these features are dependent upon, or take advantage of the new facilities provided in the POWER5 processor, including the hypervisor decrementer, a fast page mover, and simultaneous multithreading support. The technology behind the virtualization capabilities that are available on the POWER5 servers, enabling customers to better utilize the industry-leading computing capacity of the POWER5 processor, is discussed in this paper.

Operating system exploitation of the POWER5 system

The POWER5TM system incorporates several features designed to improve performance by eliminating bottlenecks and accelerating common functions used in operating systems. This paper discusses how two of the supported operating systems for POWER5--AIX® and LinuxTM--make use of these features to deliver improved system scalability and performance. In particular, the overheads for synchronizing translation-lookaside buffer (TLB) invalidations between processors, and for ensuring that the instruction cache is kept coherent by software, have been removed. The POWER5 simultaneous multithreading (SMT) implementation has features which allow operating systems to optimize the system for the kinds of applications being executed. We discuss how the operating systems approach the problems of scheduling tasks across the system, of determining when to switch processors between single-threaded (ST) and SMT mode, and of accounting accurately for CPU usage when in the SMT mode.

Advanced features in IBM POWER8 systems

The IBM POWER8™ processor includes many innovative features that enable efficient and flexible computing, along with enhancements in virtualization, security, and serviceability. These features benefit application performance, and big data and analytics computing, as well as the cloud environment. Notable features include the capabilities to dynamically and efficiently change the number of threads active on a processor, enhancing application performance via integer vector operations, encryption accelerations, and reference history arrays. Also notable is improved virtual machine density (supporting multiple simultaneous partitions per core and providing fine-grain power management), allowing continuous monitoring of system performance as well as significantly enhanced system RAS (reliability, availability, and serviceability) and security. Each of these features is technologically complex and advanced. This paper provides an in-depth description of some of these features and their exploitation through systems software and middleware. These features will continue to bring value to the system-of-record workloads in the enterprise. They also make POWER8 systems well-suited for serving the needs of newer workloads such as big data and analytics, while efficiently supporting deployment in cloud environments.