64-bit processors: A new bit for the network

The 64-bit processors from Intel Corp. and Advanced Micro Devices Inc. of Sunnyvale, Calif., could alter the landscape of high-performance computing.AMD introduced its 32/64-bit Opteron processor in the spring of 2003 as an implementation of the x86 instruction set with a 64-bit memory space. All versions of the Opteron let you run 32- and 64-bit applications and operating systems simultaneously, without sacrificing performance.HyperTransport Technology, an AMD design feature, provides a scalable bandwidth interconnect between processors, I/O subsystems and other chipsets. Support of up to three coherent HyperTransport links can provide up to 19.2 gigabytes/sec. of bandwidth per processor in the Opteron 800 series models.The Opteron's integrated double-data-rate dynamic RAM memory controller, also a new design feature, improves the way main memory is accessed, resulting in increased bandwidth, reduced memory latencies and increased processor performance.Other features of the Opteron include 64-bit wide data and address paths that incorporate a 48-bit virtual address space and a 40-bit physical address space. The architecture is built around 0.13-micron silicon-on-insulator technology that allows for lower thermal output'they run cooler than most 64-bit processors.The Operton series also has two low-power options, the EE and HE. The EE allows for embedded controllers found in networking, storage environments and telecommunications. The HE enables dense designs and can meet user needs for lower power consumption.The first release of the Intel Itanium processor in May 2001 was far from a stunning commercial success. While it performed well at scientific tasks such as simulation, it did relatively poorly running enterprise business software. According to market researcher International Data Corp. of Framingham, Mass., fewer than 500 Itanium servers were shipped in the United States, and 2,700 worldwide that year.In 2002, Intel released the Itanium 2. Unlike the Opteron, this version represents a new 64-bit architecture, rather than an extension of the x86 32-bit design.The first Itanium 2 had a 400-MHz bus, which is 12 bits wide'compared with the 8-bit width on the original Itanium'for faster data transfer rates. Its 3M integrated Level 3 cache enabled high processing rates for online transaction processing, data analysis, simulation and rendering.Last summer, Intel released several new versions of the Itanium 2 targeted at overlapping but somewhat different performance goals. They are all designed around the Intel-Hewlett-Packard Explicitly Parallel Instruction Computing (EPIC) technology. They all feature a 400-MHz bus that is 128 bits wide with 6.4-Gbps of bandwidth, and combine with the Intel E8870 chipset or OEM custom chipsets.The Itanium 2 with 6M of Level 3 cache is socket-compatible and binary-compatible with existing Itanium-based software.Versions of this chip operate at 1.5 GHz, 1.4 GHz and 1.3 GHz, with Layer 3 caches of 6M, 4M and 3M, respectively. Intel has targeted this processor series at users requiring new levels of parallelism, scalability and reliability for databases, enterprise resource planning, business intelligence and other high-performance applications.Intel also has a 1.4-GHz Itanium 2 with 1.5M of Level 3 cache for dual-processor servers and workstations. The processor is optimized for technical computing platforms and clusters, and high-performance network edge, security and software engineering purposes.For low-power situations, the company has the Low-Voltage Intel Itanium 2 processor, also designed for dual-processor systems. This 1.0-GHz processor with 1.5M of Level 3 cache needs only 62 watts for high-density projects requiring lower power.For more specific information about the Itanium 2, check out the Intel Web site, at .The accompanying chart features Opteron and Itanium 2 servers made by major vendors as well as second-tier, or white-box, server makers. As the market for them is still developing, similar products will likely appear in the months ahead.Bear in mind that a direct comparison of any of the servers is difficult. Some of them are bare-bones systems that include a chassis, motherboard with chipset, power supply and one or more processors; you can add extra hard drives, RAM, processors and storage subsystems as you see fit. Fixed-configuration servers are good to go, and require little or no customization.Which should you choose?While all the bidding isn't in yet, it appears Intel is aiming directly at very high-end 64-bit applications while AMD is concentrating more on lower-end servers in the transitional market for users wanting to move from 32-bit to 64-bit computing.Opteron costs less than Itanium 2, and can run 32-bit code directly, so legacy OSes and applications aren't wasted. Because it is based on the time-tested x86 architecture, applications are generally easier to develop for it than for the Itanium 2. For its part, the Itanium 2 arrives with excellent benchmark scores in almost all categories. Its already large Level 3 cache of 6M will soon be upgraded to 9M and could reach 24M by summer next year. It offers proven scalability.Both the Opteron and Itanium 2 are garnering about equal support from leading operating system vendors and applications developers. J.B. Miles writes from Honomu, Hawaii. E-mail him at .