October 30, 2002 1:17 PM PST

Workstation makers switch off Intel tool

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Hyperthreading--a performance-enhancing technology that lets one chip act something like two--has been available on workstations since April, but it's mostly been inactive.

Hewlett-Packard and Dell, among other workstation manufacturers, have been shipping their systems with the function turned off, according to company representatives. Right now, workstation makers say, the broad array of software used in that segment of the market doesn't take advantage of the technology yet. Users, though, can easily turn on the hyperthreading function if they wish.

Although the situation will change, the wrinkle in the workstation market--where Intel said users could see performance benefits of up to 30 percent on select applications--underscores the difficulties in gaining broad acceptance and use for a new technology. Only 30 applications had been fully optimized for Intel's Pentium 4 processor in the first nine months the chip was on sale.

Conceivably, the workstation experience could also provide a litmus test of what some PC makers might do with hyperthreading come Nov. 14, when the technology arrives on desktop computers.

If not enough desktop software comes out that is separated into multiple computing strands, a process known as threading, computer makers might decide to keep the new Intel technology dormant, said Peter Glaskowsky, editor in chief of The Microprocessor Report. With other software, hyperthreading could even be a drawback.

"If you are running single-threaded applications, it will reduce your performance," Glaskowsky said.

Intel disputes this. Although a small number of applications might see a minor dip in performance, "the very, very vast majority of applications" will benefit or, at a minimum, not be affected when running on Windows XP, said Shervin Kheradpir, director of performance benchmarks at Intel.

Users running multithreaded applications, such as Photoshop, will see up to a 25 percent to 30 percent boost in performance, Intel said. Users running two applications at once will see similar performance boosts and experience far fewer hang-ups.

An Intel representative said the company is recommending that PC makers turn on the technology in upcoming Windows XP machines.

Nonetheless, the company acknowledged that acceptance in the workstation market remains largely on hold because software adjustment takes time.

The threading primer
Hyperthreading, announced in August 2001, is Intel's take on simultaneous multithreading, a microprocessor design concept that essentially makes a chip behave more efficiently. With threading, different regions inside the processor, such as the floating-point unit for decimal math and the integer unit, can process different applications, or application threads, at the same time.

In contrast, most current processors behave like a wood chipper, processing threads in a fairly linear fashion. Therefore, many of the traditional processor's resources remain dormant while others work.

When the technology was announced, Intel said that a workstation with hyperthreaded Xeon chips running Alias-Wavefront, a graphics application, achieved a 30 percent improvement in tests.

To operating systems and applications, chips with hyperthreading look like two chips, and that's where the hitch lies. Software needs to be broken into threads before it can run on two chips simultaneously.

In the server market, applications and operating systems have already been threaded. In workstations, the practice isn't as prevalent, said an HP representative. As a result, the function is turned off in the company's X4000 workstation.

HP in the coming weeks plans to come out with a new line of Windows 2000 and Windows XP workstations, but hyperthreading won't be available. An HP representative said most of the applications for workstations, predominately tailored for Windows 2000, don't take advantage of the technology. A Dell representative echoed the sentiment.

"In workstations, hyperthreading remains application-dependent," said the representative, who added that Dell's Precision 530 workstation comes with the hyperthreading function turned off. Both HP and Dell, though, make the technology easy to turn on.

With upcoming desktops, the situation will be reversed. Windows XP has been optimized for the technology and so have many applications.

Performance gains will be the largest when the application is also threaded (as well as optimized specifically for hyperthreading), but gains will still occur on unvarnished applications, said Dean McCarron, an analyst at Mercury Research.

"I'm fully expecting at least a modest improvement" in most situations, McCarron said.

Still, Glaskowsky said problems could occur with single-threaded applications even on a multithreaded operating system. If the processor is running two threads, the chip has to split its cache--a reservoir of memory located on the processor--and other shared resources. Historical examples have shown that regular software that?s run on computers with two chips runs worse than on single-processor boxes.

"You need something that was designed to run on two processors," said Glaskowsky. Otherwise, "it adds a dose of dissatisfaction."

 

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