Sean M. Carey

Design methodology for the S/390 parallel enterprise server G4 microprocessors

This paper describes the design methodology employed in the design of the S/390® Parallel Enterprise Server G4 microprocessors. Issues of verifying design metrics of area, power, noise, timing, testability, and functional correctness are discussed within the context of a transistor-level custom design approach. Practical issues of managing the complexity of a 7.8-million-transistor design and encouraging design productivity are introduced.

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.

760 MHz G6 S/390 microprocessor exploiting multiple Vt and copper interconnects

The G6 system is a sixth generation CMOS server for the S/390 line of products featuring a 12+2 SMP size and significant frequency improvements obtained through the use of low-Vt devices and copper interconnects. The microprocessor operates at 760 MHz at the fast end of the process distribution. The system ships at 637 MHz in a 12+2 chilled SMP configuration. Measured system performance on the 12 way is 1600 S/390 MIPs, providing over 50% more performance than the G5. This microprocessor uses CMOS7S technology, which has a 0.2 /spl mu/m process. The chip uses 6 levels of copper metal plus an additional layer of local interconnect on a 14.6/spl times/14.7 mm/sup 2/ die with 25M transistors (7M logic/18M array). The power supply is 1.9 V and the chip power is 33 W at 637 MHz.

Circuit and Physical Design Implementation of the Microprocessor Chip for the zEnterprise System

This paper describes the circuit and physical design features of the z196 processor chip, implemented in a 45 nm SOI technology. The chip contains 4 super-scalar, out-of-order processor cores, running at 5.2 GHz, on a die with an area of 512 mm2 containing an estimated 1.4 billion transistors. The core and chip design methodology and specific design features are presented, focusing on techniques used to enable high-frequency operation. In addition, chip power, IR drop, and supply noise are discussed, being key design focus areas. The chips ground-breaking RAS features are also described, engineered for maximum reliability and system stability.

Voltage Noise in Multi-Core Processors: Empirical Characterization and Optimization Opportunities

Voltage noise characterization is an essential aspect of optimizing the shipped voltage of high-end processor based systems. Voltage noise, i.e. Variations in the supply voltage due to transient fluctuations on current, can negatively affect the robustness of the design if it is not properly characterized. Modeling and estimation of voltage noise in a pre-silicon setting is typically inadequate because it is difficult to model the chip/system packaging and power distribution network (PDN) parameters very precisely. Therefore, a systematic, direct measurement-based characterization of voltage noise in a post-silicon setting is mandatory in validating the robustness of the design. In this paper, we present a direct measurement-based voltage noise characterization of a state-of-the-art mainframe class multicoreprocessor. We develop a systematic methodology to generate noise stress marks. We study the sensitivity of noise in relation to the different parameters involved in noise generation: (a) stimulus sequence frequency, (b) supply current delta, (c) number of noise events and, (d) degree of alignment or synchronization of events in a multi-core context. By sensing per-core noise in a multi-core chip, we characterize the noise propagation across the cores. This insight opens up new opportunities for noise mitigation via workload mappings and dynamic voltage guard banding.

Circuit and Physical Design of the zEnterprise™ EC12 Microprocessor Chips and Multi-Chip Module

This work describes the circuit and physical design implementation of the processor chip (CP), level-4 cache chip (SC), and the multi-chip module at the heart of the EC12 system. The chips were implemented in IBMs high-performance 32nm high-k/metal-gate SOI technology. The CP chip contains 6 super-scalar, out-of-order processor cores, running at 5.5 GHz, while the SC chip contains 192 MB of eDRAM cache. Six CP chips and two SC chips are mounted on a high-performance glass-ceramic substrate, which provides high-bandwidth, low-latency interconnections. Various aspects of the design are explored in detail, with most of the focus on the CP chip, including the circuit design implementation, clocking, thermal modeling, reliability, frequency tuning, and comparison to the previous design in 45nm technology.

609 MHz G5 S/399 microprocessor

The IBM G5 system is a fifth-generation CMOS server for the S/390 line of products with functionality improvements such as an instruction branch target buffer (BTB) and an IEEE compliant binary floating-point. The microprocessor operates at 600 MHz at the fast end of the process distribution, although the system is shipped at 500 MHz in a 10+2 SMP configuration. Measured system performance on the 10 way is 1069 S/390 MIPs. This microprocessor uses a 0.25 mum CMOS process. The chip uses 6 levels of metal plus an additional layer of local interconnect and is 14.6times14.7 mm2 with 25 M transistors (7 M logic/18 M array). Power supply is 1.9 V. Chip power is 25 W at 500 MHz

4.1 22nm Next-generation IBM System z microprocessor

The next-generation System z design introduces a new microprocessor chip (CP) and a system controller chip (SC) aimed at providing a substantial boost to maximum system capacity and performance compared to the previous zEC12 design in 32nm [1,2]. As shown in the die photo, the CP chip includes 8 high-frequency processor cores, 64MB of eDRAM L3 cache, interface IOs (“XBUS”) to connect to two other processor chips and the L4 cache chip, along with memory interfaces, 2 PCIe Gen3 interfaces, and an I/O bus controller (GX). The design is implemented on a 678 mm2 die with 4.0 billion transistors and 17 levels of metal interconnect in IBMs high-performance 22nm high-x CMOS SOI technology [3]. The SC chip is also a 678 mm2 die, with 7.1 billion transistors, running at half the clock frequency of the CP chip, in the same 22nm technology, but with 15 levels of metal. It provides 480 MB of eDRAM L4 cache, an increase of more than 2× from zEC12 [1,2], and contains an 18 MB eDRAM L4 directory, along with multi-processor cache control/coherency logic to manage inter-processor and system-level communications. Both the CP and SC chips incorporate significant logical, physical, and electrical design innovations.

Robust power management in the IBM z13

The power management strategy adopted for the IBM z13™ processor chip (referred to as the CP or Central Processor chip) is guided by three basic principles: (a) controlling the peak power consumption by setting a realistic limit on the so-called thermal design power or thermal design point (TDP) driven by customer workloads and maximum-power stress microbenchmarks; (b) reduction of the voltage margin by using a novel dynamic guard-banding technique; and (c) the creation of a rich new set of fine-grained, time-synchronized sensors that track performance, power, temperature, and power management behavior for a running machine. A prime requirement of the power management architecture is that the efficient control mechanisms be designed in such a manner that the high standards of IBM z Systems™ application performance and reliability be maintained without any compromise. In this paper, we describe the key features constituting the z13 CP robust power management architecture and design that meet the stipulated objectives.

5.5GHz system z microprocessor and multi-chip module

The new System z microprocessor chip (“CP chip”) features a high-frequency processor core running at 5.5GHz in a 32nm high-κ CMOS technology [1], using 15 levels of metal. This chip is a successor to the 45nm product [2], with significant improvements made to the core and nest (i.e. the logic external to the cores) in order to increase the performance and throughput of the design. Also, special considerations were necessary to ensure robust circuit operation in the high-κ technology used for implementation. As seen in the die photo, the chip contains 6 processor cores (compared to 4 cores in the 45nm version), and a large shared 48MB DRAM L3 cache. Each core includes a pair of data and instruction L2 SRAM caches of 1MB each. In addition, the chip contains a memory control unit (MCU), an I/O bus controller (GX), and two sets of interfaces to the L4 cache chips (also in 32nm technology). The CP chip occupies 598 mm2, contains about 2.75B transistors, and has 1071 signal IOs.