The Battle in 64 bit Land Revisited

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[This is an update of an article I wrote a year ago entitled “The Looming Battle in 64 bit Land“. Since then there have been a number of important events (and non-events) in this important market segment. The milestones achieved by each of the major players over the past 12 months are reviewed and the near future competitive prospects of the major 64 bit microprocessor families are examined.]

The New Guy Ships While the Incumbents Slip

The most important event in the 64-bit universe over the past year happened mere weeks ago. Intel officially unveiled its Itanium processor. HP, SGI, and Dell were quick to show off moderately priced entry-level technical workstations based on Itanium. IBM and Compaq also pledged support for Itanium in future products. This event is significant because Itanium’s IA64 instruction set architecture is the subject of considerable technical controversy. Itanium also marks the introduction of a new business model for 64 bit processors that could thoroughly shake up the “old boy’s club”, a select group of high-end system vendors, each with their own associated RISC processor architecture. To add insult to injury, McKinley, the second generation IA64 device, saw first silicon and was functional enough to show off to the faithful at Intel’s developer’s forum in February.

Although the development delays associated with Itanium and the entire IA64 program are now legendary, and even the source of amusement for some in the industry, the past year hasn’t been kind to the 64-bit RISC incumbents either. Sun Microsystems finally shipped their UltraSPARC-III (US-III) after a multi-year post design development cycle that included at least one full process shrink. Despite its extended gestation period the US-III is a surprisingly weak performer. The promised higher frequency follow-on US-III device based on copper interconnect has yet to materialize. This has lent credibility to rumors that the US-III was experiencing yield problems and Sun was considering an alternative fab partner to complement or replace Texas Instruments.

The traditional 64 bit performance leader, Compaq’s Alpha, had yet another year of showing great technical promise in ISSCC presentations, yet having precious little in the way of new speed grades or devices with higher levels of integration drop out of the product development pipeline. The EV7, desperately needed to yank Alpha performance safely above the x86 rising tide and confront the specter of McKinley, apparently taped out only recently after a conspicuous and unexplained delay. An anticipated speed bump of EV68 up to 1 GHz, to be officially unveiled this month or next, should allow Alpha, currently in third place in both SPECint2k and SPECfp2k, to pull into the lead on both performance metrics.

With Itanium unveiled, much speculative attention now shifts to IBM and its POWER4 chip level multiprocessor (CMP). Described in a previous article, this dual processor device demonstrates IBM’s clear intention to compete head to head with future IA64 and Alpha processors for performance supremacy in the server arena. The initial version of this device, in 0.18 um SOI copper CMOS, was scheduled to be revealed later this year. However, there are rumors that IBM may delay introducing the POWER4 commercially until it is ported/shrunk to a 0.13 um process.

Even if POWER4 skips the current process generation, IBM’s 0.18 um fab will not lack a 64-bit processor. HP’s third and most recent attempt to hide a superscalar RISC CPU in an SRAM, the PA-8700, looks set to make a summer introduction courtesy of big blue. At 750 MHz the new HP processor is fast enough to grab the lead in SPECint2k (peak).

HP’s efforts to keep its proprietary RISC family competitive long enough move its customer base to IA64 are mirrored by SGI. SGI bravely soldiers on with derivatives of the short pipeline MIPS R10k processor core. Its latest incarnation, called the R14k, manages to easily outperform the US-III despite the Sun device’s 50% clock rate advantage.

The performance of 64 bit microprocessors currently available, or available within several months, are shown below in Figure 1. The performance of the fastest Intel and AMD x86 processors currently available are also included for reference purposes.


Figure 1 Current and Imminent 64 Bit MPUs (x86 MPUs shown for reference)

Figure 1 shows clearly that while the Itanium leads all currently available 64-bit RISC MPUs in floating point performance as measured by SPECfp_base2k, its integer performance as measured by SPECint_base2k barely matches that of the weakest RISC processor shown, the UltraSPARC-III.


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