In-Depth

Intel Promises Improved Performance

Software will enhance Itanium’s 32-bit performance later this year

• By Stephen Swoyer
• 04/29/2003

Intel’s new software technology, called the IA-32 Execution Layer, is expected to debut later this year. The upshot, Intel representatives said last week, is that it will enable a 1.5 GHz Itanium 2 to crunch 32-bit code about as fast as a 1.5 GHz Xeon MP chip. Intel’s current fastest microprocessor is its 2.0 GHz Xeon MP.AMD’s 64-bit Opteron chip is said to run 32-bit code with little, if any, performance loss. The chip also boasts 64-bit support, as well. Some analysts have suggested that Itanium’s poor 32-bit performance creates an opening for Opteron, as most IT organizations already have substantial investments in 32-bit applications designed to run on Intel hardware. (See http://info.101com.com/default.asp?id=1153)

“Itanium has not really taken off for this reason,” comments Gordon Haff, a senior analyst with consultancy Illuminata Inc. “There is an opportunity here for AMD to come in with [Opteron] and maybe attract some customers with its message.”

Intel describes the IA-32 Execution Layer as a software module that plugs into an operating system and which emulates a 32-bit x86 microprocessor. This approach presupposes ISV support, of course, and Intel confirms that it is working with Microsoft and with a variety of Linux distributors to develop IA-32 Execution Layer modules for their operating environments.

The 32-bit performance of Intel’s Itanium Processor Family (IPF) architecture has been problematic since the first-generation Itanium microprocessor debuted in 2001. That’s largely because Itanium was designed from the ground up as a 64-bit microprocessor, complete with a new instruction set, dubbed EPIC. Even when Itanium 2 debuted last spring, the next-generation 64-bit chip was still plagued by sub-par performance when executing 32-bit x86 (IA-32) code.

The IA-32 Execution Layer represents a departure for Intel, which up to now had incorporated IA-32 support directly into Itanium’s silicon. Aside from dreadful 32-bit performance, this resulted in a number of other feature set shortcomings, specifically with respect to accommodating new extensions to the x86 instruction set, such as Intel’s SSE and SSE II 3-D and multimedia enhancements. Because the IA-32 Execution Layer runs 32-bit code in emulation, it can easily be updated to incorporate these and other x86 extensions.

Among analysts, Nathan Brookwood, a principal with microprocessor consultancy Insight64, expects that “if [the IA-32 Execution Layer] works, it will mitigate AMD’s 32/64-bit capability claim.” At the same time, Brookwood acknowledges that he doesn’t “have any way to assess how effective the IA32 Execution Layer will be.”

After all, analysts say, software emulation has traditionally entailed performance shortcomings of its own. Whether the IA-32 Execution Layer offers substantial performance gains over Itanium’s integrated silicon-based 32-bit execution routines remains to be seen.

In the final analysis, suggests Insight64’s Brookwood, much of the hype surrounding the clash of Itanium and Opteron misses the point. “In my view, it will be many years before Opteron and Itanium actually compete directly in the market. For the foreseeable future, Itanium is (mostly) a high-end play, and Opteron is (mostly) a low-end [under $25,000] play.”