Lee Evan Eisen

IBM POWER6 accelerators: VMX and DFU

The IBM POWER6™ microprocessor core includes two accelerators for increasing performance of specific workloads. The vector multimedia extension (VMX) provides a vector acceleration of graphic and scientific workloads. It provides single instructions that work on multiple data elements. The instructions separate a 128-bit vector into different components that are operated on concurrently. The decimal floating-point unit (DFU) provides acceleration of commercial workloads, more specifically, financial transactions. It provides a new number system that performs implicit rounding to decimal radix points, a feature essential to monetary transactions. The IBM POWER™ processor instruction set is substantially expanded with the addition of these two accelerators. The VMX architecture contains 176 instructions, while the DFU architecture adds 54 instructions to the base architecture. The IEEE 754R Binary Floating-Point Arithmetic Standard defines decimal floating-point formats, and the POWER6 processor--on which a substantial amount of area has been devoted to increasing performance of both scientific and commercial workloads--is the first commercial hardware implementation of this format.

Stretching the limits of clock-gating efficiency in server-class processors

Clock-gating has been introduced as the primary means of dynamic power management in recent high-end commercial microprocessors. The temperature drop resulting from active power reduction can result in additional leakage power savings in future processors. In this paper we first examine the realistic benefits and limits of clock-gating in current generation high-performance processors (e.g. of the POWER4/spl trade/ or POWER5/spl trade/ class). We then look beyond classical clock-gating: we examine additional opportunities to avoid unnecessary clocking in real workload executions. In particular, we examine the power reduction benefits of a couple of newly invented schemes called transparent pipeline clock-gating and elastic pipeline clock-gating. Based on our experiences with current designs, we try to bound the practical limits of clock gating efficiency in future microprocessors.

A 5.2GHz microprocessor chip for the IBM zEnterprise™ system

The microprocessor chip for the IBM zEnterprise 196 (z 196) system is a high-frequency, high-performance design that adds support for out-of-order instruction execution and increases operating frequency by almost 20% compared to the previous 65nm design, while still fitting within the same power envelope. Despite the many difficult engineering hurdles to be overcome, the design team was able to achieve a product frequency of 5.2GHz, providing a significant performance boost for the new system.

The zEnterprise 196 System and Microprocessor

The zEnterprise 196 is the latest IBM System zSeries mainframe computer, which builds on IBMs 46-year heritage of compatible enterprise-class machines. This design advances the prior z10 processor pipeline with out-of-order execution to achieve considerable performance gains in legacy online transaction processing and computationally intensive workloads. This article describes the system structure and details of this new high-frequency microprocessor.

A 3.0 W 75SPECint92 85SPECfp92 superscalar RISC microprocessor

This superscalar microprocessor is a 32b implementation of the PowerPC Architecture. With an estimated performance/power ratio of 25SPECint92/W at 80 MHz, this RISC style chip offers workstation-level performance packed into a low-power consumption, low-cost design ideal for notebooks and desktop computers.<<ETX>>

A 1.2 W 66 MHz superscalar RISC microprocessor for set-tops, video games, and PDAs

This 32 b superscalar processor, having 18 mW/MHz projected power consumption at 66 MHz, is designed for desktop companions and high-end embedded multimedia applications with graphics-intensive requirements such as high-performance video games. This processor, the latest member of the PowerPC microprocessor family, can also be used in other low-power computing applications. The processor is fabricated in a 3.3 V, 0.5 m, 4-level metal CMOS resulting in 1 M transistors in a 7.07/spl times/7.07 mm/sup 2/ chip. Dual 4 kB instruction and data caches coupled to a high-performance 64 b multiplexed bus and separate execution units (float, integer, branch, and load-store) result in 2 instructions per clock cycle peak rate. Low-power design includes dynamically-powered-down execution units. Standby power is <2 mW. CPU to bus clock ratios of 2/spl times/ and 3/spl times/ allow control of system power while maintaining processor performance.