April 23, 2003 4:00 AM PDT
Intel plans Itanium course correction
The move is meant to address a weakness that hampered the adoption of high-end, Itanium-based systems.
Itanium chips currently include circuitry that lets them run the 32-bit software of "IA-32" processors such as Xeon or Pentium. But that circuitry's performance has been so poor that not even Intel advocates its use.
The new software approach, called the IA-32 Execution Layer and code-named btrans, will give the forthcoming 1.5GHz Itanium 2 the ability to run 32-bit software about as fast as a 1.5GHz Xeon MP, Intel spokeswoman Barbara Grimes confirmed.
The software could make Itanium processors more appealing to customers that have been reluctant to use Itanium systems because of the difficulty of running older 32-bit software, analysts said. In addition, Intel's new strategy could undermine one of the key advantages of the Opteron processor AMD introduced Tuesday because it allows customers to gradually transition to new applications without having to discard their current applications.
AMD's Opteron is designed to run 32-bit code as fast as possible, meaning current applications don't need to be replaced. Itanium, on the other hand, emphasizes 64-bit software with the ability to run older 32-bit software as only a second priority. With both Opteron and Itanium, the software must be rebuilt if it is to take advantage of the 64-bit features, such as the ability to address large amounts of memory.
"A customer who likes Itanium but also has 32-bit workloads they can't move immediately to Itanium is really in a quandary. AMD's claim to fame is that you can run that 32-bit software till the cows come home and have 64 bits, too," said Insight 64 analyst Nathan Brookwood. However, Intel's software emulation technology "does blunt AMD's story a bit," he said.
The emulation software's speed, if it meets Intel's expectations, wouldn't be far behind the top 2GHz speed of today's Xeon MP, a chip that like Itanium is designed for multiprocessor servers. It would lag more substantially behind the speed of 3.06GHz Xeons for dual-processor computers, though.
Still, it would be vastly better than the current technology for executing software for IA-32, also called x86 after earlier Intel processors such as the 386 and 486.
"They said Itanium would never be their fastest 32-bit processor, but it would be in the ballpark. The original x86 hardware execution mechanism wasn't in the ballpark. It was barely in the parking lot around the ballpark," Brookwood said.
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The emulation move is also likely to be more palatable to customers than "Yamhill," an Intel project that sources have said is similar to AMD's 64-bit extensions to Intel's 32-bit design rather than the dramatic departure Itanium represents. "This could be another way to respond to AMD without necessarily compromising their Itanium strategy," Brookwood said.
There are risks, though. Emulating one chip on another has historically been difficult and is most often used as a crutch during migrations, such as when Digital Equipment switched from VAX microprocessors to the Alpha. Apple managed the feat when it moved its computers from Motorola's 68000 line of processors to its PowerPC line, but could do so only because the new chip represented such a performance bump that it could offset some of the performance hit caused by running an emulator.
Intel's Execution Layer software is a module that plugs into an operating system and emulates the IA-32 processor, Grimes said. Intel is working with Microsoft and Linux sellers on having the software included in their operating systems.
Microsoft and top Linux seller Red Hat didn't immediately respond to requests for comment. SuSE declined to comment, but a source at the company said the second-largest Linux seller is working to support the technology.
"We are working with Microsoft, with the Linux (project) maintainers and Linux operating system distributors to ensure the Execution Layer is functional and ready for quick, broad deployment when it's validated," Grimes said.
The Itanium effort
Itanium is an ambitious attempt to create a chip architecture that will last for more than a decade. Hewlett-Packard initiated the project in 1988 then signed a partnership with Intel to design and manufacture the chip in an effort to spread the processor as widely as Pentium instead of seeing it consigned to the small niche many high-end processors occupy.
Although the second-generation Itanium solved performance problems, it didn't change the larger problem: that software has to be rebuilt to take advantage of the chip's abilities. And because the anemic 32-bit performance made it hard to run older software, Intel rivals such as AMD and Sun Microsystems were able to exploit the fact that their new chips don't force customers to deal with a "binary break" that makes older software useless.
And that led Intel to consider emulation technology.
"If Intel could find a way to have IA-32 code run reliably and relatively quickly on an Itanium processor, it could only help its adoption," said Illuminata analyst Gordon Haff.
HP, the company with the biggest stake in the success of Itanium--because it's moving its entire server line to the chip family--is supportive of the move.
"We're pleased with any technology that will boost the performance of Itanium-based systems for our customers. We expect this (IA-32 Execution Layer) to help customers as they migrate their applications from 32-bit to 64-bit on Windows and Linux," said Brian Cox, worldwide product line manager for HP Business Critical Systems.
Intel will keep the hardware-based IA-32 support at least through the Itanium II 9M model due to arrive in 2004, Grimes said. She declined to say whether the company would rely solely on the Execution Layer software after that, but analysts believe that move is likely.
Removing the hardware component likely would liberate Itanium from design compromises the chip needed to accommodate the 32-bit code, Brookwood said. And Mercury Research analyst Dean McCarron noted that "getting rid of the hardware piece of it means fewer transistors, smaller die size, and (that Itanium would be) more manufacturable."
Grimes, however, said removing the hardware support wouldn't change the processor size significantly.
Several factors will determine the future of the emulation layer. On one hand, Intel engineers could improve the software in succeeding generations, and its performance will increase as newer, faster Itanium models debut. On the other hand, Intel has been aggressively boosting the speeds of its 32-bit chips.
One advantage of the emulation software is that it can be more easily adapted to execute IA-32 instructions that older IA-32 chips lacked. For example, the existing Itanium circuitry can't execute the SSE instructions that have been boosting some mathematical operations since the days of Pentium III, much less the SSE2 follow-on in Pentium 4 and whatever might come later.
The new layer doesn't change Intel's overall Itanium strategy of encouraging computing companies to rebuild their software for Itanium, Grimes said. Customers needing top 32-bit software performance should still buy Xeon systems, she said.
"Itanium is first and foremost designed to run 64-bit," Grimes said. "The 32-bit support is in there as a migration path for people as they get over to 64-bit, or for nonperformance (critical) applications they might not want to migrate."