Intel shows off simultaneous multithreading

Intel demonstrated its 'hyperthreading' technology (formerly known as Jackson) at the IDF. Here's how it works, according to CNet:

Technically, hyperthreading takes advantage of additional registers--circuits that help manage data inside a chip--that come on existing Pentium 4's but aren't used. Through these registers, the processor can handle more tasks at once by taking better advantage of its own resources. The chip can direct instructions from one application on its floating-point unit, which is where the heavy math is done, and run parts of another application through its integer unit.

A chip with hyperthreading won't equal the computing power of two Pentium 4's, but the performance boost is substantial, Poulin said. A workstation with hyperthreaded Xeon chips running Alias-Wavefront, a graphics application, has achieved a 30 percent improvement in tests, he said. Servers with hyperthreaded chips can manage 30 percent more users.

The downside is that apps have to be rewritten to take advantage of 'hyperthreading'. This might be difficult to get developers to do, but if the performance gains to be offered by hyperthreading are as substantial as Intel claims, I suspect developers of high-performance applications might get aboard reasonably quickly. The CNet article seems a little unclear on whether already multithreaded apps would need to be modified to use Intel's hyperthreading. (Every time I read that part of their article, I decide they mean a different thing...) The technology will show up in server and workstation (read: Xeon) chips in 2002, and on the desktop in 2003. Intel also showed off a 3.5 Ghz Pentium 4 (supercooled, I'm guessing, but still impressive), running Quake 3 "and managing different video streams simultaneously". The last week has been a good one for Intel...

SAN JOSE, Calif.--Intel showed off a new chip technology Tuesday that, if successful, will allow one chip to act like two.

Called "hyperthreading," the new technology essentially takes advantage of formerly unused circuitry on the Pentium 4 that lets the chip operate far
more efficiently--and almost as well as a dual-processor computer. With it, a desktop can run two different applications simultaneously or run a single application much faster than it would on a standard one-processor box.

"It makes a single processor look like two processors to the operating
system," said Shannon Poulin, enterprise launch and disclosure manager at
Intel. "It effectively looks like two processors on a chip."

Paul Otellini, general manager of the Intel Architecture Group, demonstrated the hyperthreading technology at the Intel Developer's Forum here Tuesday.

In the same speech, he showed off a 3.5GHz Pentium 4 running the computer game "Quake 3" and managing four different video streams simultaneously. The Pentium 4 demonstration didn't depend on Hyper-Threading; instead, it came out as part of Intel's effort to show how consumers and software developers will continue to need faster PCs.

"There are a lot of tremendous applications on the horizon that will consume the MIPS (millions of instructions per second)," Otellini said. "Gigahertz are necessary for the evolution and improvement of computing."

Technically, hyperthreading takes advantage of additional registers--circuits that help manage data inside a chip--that come on existing
Pentium 4's but aren't used. Through these registers, the processor
can handle more tasks at once by taking better advantage of its own
resources. The chip can direct instructions from one application on its
floating-point unit, which is where the heavy math is done, and run parts of another application through its integer unit.

A chip with hyperthreading won't equal the computing power of two Pentium
4's, but the performance boost is substantial, Poulin said. A workstation with hyperthreaded Xeon chips running Alias-Wavefront, a graphics application, has achieved a 30 percent improvement in tests, he
said. Servers with hyperthreaded chips can manage 30 percent more users.

Will developers climb aboard?

The open question is whether software developers will latch onto the idea.
Software applications will need to be rewritten to take advantage of
hyperthreading, and getting developers to tweak their products can take an
enormous amount of time.

Intel, for instance, has been working for well over a year to get developers
to rewrite their programs to take full advantage of the features of the
Pentium 4, which has been out for approximately nine months. The company
even changed the migration program to speed the process of optimizing
Pentium III applications for the Pentium 4.

Still, to date, only 30 applications have been enhanced to take full
advantage of the Pentium 4, according to Louis Burns, vice president and
general manager of the Desktop Platforms Group at Intel. But more are
on the way, he said.

Otellini acknowledged that recruiting developers will take time.

"The real key is going to be to get the applications threaded, and that takes a lot of work," he said.

Nonetheless, adopting the technology to server and workstations applications should be fairly easy if the application already runs on dual-processor systems, other Intel officials said. "Thread your applications and drivers and OSes to take advantage of this relatively free performance," Otellini asked developers during his speech.

Hyperthreading, which will appear in servers and workstations in 2002 and
desktops in 2003, is part of an overall Intel strategy to find new ways to
squeeze more performance out of silicon. For years, the company has largely
relied on boosting the clock speed and tweaking parts of the
chip's architecture to eke out gains.

The performance gains to be achieved from boosting the clock speed, however,
are limited. In all practicality, most users won't experience that much
realistic difference between a 1GHz computer and one that contains a 2GHz
chip, according to, among others, Dean McCarron, an analyst at Mercury
Research.

Ideally, hyperthreading, which has been under development for four and a
half years, will show meatier benefits. An individual could play games
while simultaneously downloading multimedia files from the Internet with a
computer containing the technology, Poulin predicted.

Hyperthreaded chips would also be cheaper than dual-processor computers.
"You only need one heat sink, one fan, one cooling solution," he said, along
with, of course, one chip.

Chips running hyperthreading have been produced, and both Microsoft's
Windows XP and Linux can take advantage of the technology, according to Poulin.

Computers containing a single hyperthreaded chip differ from dual-processor
computers in that two applications can't take advantage of the same processor substructure at the same time.

"Only one gets to use the floating point at a single time," Poulin said.

On other fronts, Intel on Tuesday also unveiled Machine Check Architecture, which allows servers to catch data errors more efficiently. The
company will also demonstrate McKinley for the first time. McKinley is the
code name for the next version of Itanium, Intel's 64-bit chip that competes
against Sun's UltraSparc. McKinley is due in demonstration systems by the
end of this year.

CNet.