Dual-core CPUs have been commercially available since 2000 when IBM first introduced the IBM POWER4. They provide a method for gaining greater performance while avoiding the increases in form-factor, incremental heat and power requirements associated with the higher feature density of fast single-core processors. In pursuing dual-core CPUs, the major IC manufacturers have acknowledged that the historical approach of gaining performance by simply increasing CPU feature density has reached diminishing practical returns.

The current generation of high-performance CPUs (Table 1) is 90 nanometers (nm) between surface features, thus entering the realm of bona fide nanotechnology, which is 100 nm and below. However, at this extreme density, there are many unwanted effects. The industry has grown accustomed to ever improving performance with each CPU generation, but the current level of miniaturization of feature sizes is forcing IC manufacturers to look to more innovative solutions.

The problems caused by extreme feature density are interrelated. Electrical features in extreme proximity produce quantum effects, i.e., electrons that randomly tunnel across the CPU’s features causing interference with normal signal transmission. At the highest frequencies, tunneling can become so extreme that it totally negates signal recognition.

To drive high performance across smaller, more powerful transistors requires more power. In turn, higher power results in unacceptable levels of waste heat as power (wattage) increases and produces more unwanted quantum effects. Machines with dense CPUs running at higher wattage are noisier, because they require additional, more powerful fans for cooling. Fan motors add yet more electrical noise.

Dual-core processors, such as the AMD Opteron, can mitigate these problems while at the same time enabling significant increases in performance.

The AMD Opteron Dual-Core Processor

The AMD Opteron processor is a high-density, 90-nm CPU, packing 233 million transistors on a 199 mm2 die. The chip is microarchitected to lessen unwanted effects, principally through thread-level parallelism. It uses other technology, such as HyperTransport interconnect, in order to work smarter, not hotter.

Dual-core processors are most effective in applications that feature highly parallel processes. However, the technology can realize significant gains when applied to nearly any application that involves all but the simplest sequential number crunching. IBM, which has incorporated the dual-core AMD processor in some of its servers, reports 60% faster processing with a 2.2 GHz dual-core AMD Opteron processor versus AMD’s 2.6 GHz single-core processor in tests using the Linpack HPL benchmark. Other tests, such as floating-point and integer processing, have yielded even better gains (Figure 1).

This increase in performance has generated interest among OEMs designing embedded systems for demanding, low-latency, high-performance applications, such as industrial automation, military, medical and security imaging, storage and telecommunications. The dual-core AMD Opteron processor enables basic reference designs that can be modified to meet these systems’ needs for compactness, design longevity, lower power consumption, low latency and high reliability, often in harsh environments.

In response to market forces and evolving technology in x86 processors, such as the AMD Opteron and Pentium M, many designers of high-performance embedded systems are turning from highly specialized platforms to x86-based solutions. These systems typically run either Windows Embedded XP or Linux.

Regardless of the operating system chosen, it should be dual-core-aware in order to provide the benefit of multithreading. The dual-core AMD Opteron provides improved 32-bit legacy application support, in addition to concurrent 64-bit performance. This ability to support legacy applications enables a smooth upgrade path in the enterprise market and expands the dual-core Opteron’s flexibility in the high-performance embedded market.

Terascala, which manufactures storage appliances for Linux-based clusters, is utilizing the dual-core Opteron CPU on motherboards co-designed and manufactured by WIN Enterprises. The combination of HyperTransport connectivity, improved microarchitecture and dual-core CPUs enables these storage systems to provide the high performance, scalability and high I/O throughput required by their enterprise customers.

Since Terascala rack-mounts several storage units into its cabinets, the benefits of a high-performance processor with a smaller footprint and less waste heat are especially important in serving data storage application needs. In addition, transaction-intensive storage environments require the dual-core architecture’s low latency, which approaches real-time performance (Figure 2).