The fast show

At the Intel Developer Forum, the microprocessor giant demonstrated the impact that 'hyper-threading' will have on a PC's performance. But is the megahertz race over, asks Jack Schofield?

The fast show


'Consumers don't care about megahertz," the number we use to describe a microprocessor's speed, "what they really care about is realised performance." So says Pat Gelsinger, Intel's chief technology officer, and the man who directs its research. This sounds almost heretical from a company that has spent three decades shipping chips that run faster and faster. However, the not-so-hidden message from Paul Otellini, Intel's president and chief operating officer, is that the next range of desktop processors "will give up to a 25% increase in performance" at the same clock speeds, thanks to a new ingredient - "hyper-threading".

The basic idea is to enable a Pentium to run different streams of program instructions - threads - in parallel. On a multiprocessor server, the different threads might be run on separate processors. With Intel's hyper-threading (HT), a single processor does the job. In theory, you get two "logical" processors for the price of one physical processor.

The catch is that you have to buy a new processor to get it, and Otellini says a 3GHz HT Pentium will be out by the end of the year. "We'll have 20m desktops shipping with hyper-threading next year."

HT is not new: it's already available in Intel's Xeon versions of the Pentium, designed for high-powered workstations and multiprocessor servers. Multi-threading has also been used in software for almost 30 years. Why hasn't Intel offered it to desktop users before?

"What's changed is that, with Windows XP, you now have a multi-threaded operating system that you can take advantage of in the desktop space," says Gelsinger. He concedes that Windows NT has supported multiprocessing and multi-threading since 1993, "but now it's come to the mainstream for the first time."

This is good news for consumers, who will get a PC that operates more smoothly and is better at doing more than one thing at a time - particularly if one of those things is something like speech recognition or capturing video. It's great for a depressed PC industry, which can now sell a slightly better PC to people who already have a perfectly adequate one. And it's best of all for the deadly duo, Intel and Microsoft, when a new version of Windows justifies buying a PC with a new Intel processor, and vice versa. It's called "the upgrade spiral". It's very profitable.

Intel demonstrated HT at its latest Intel Developer Forum, held in San Jose, California, last week. More than 4,000 developers turned up from all over the globe for classes that ranged from a hands-on workshop on accelerating your Universal Plug & Play development to the easy-peasy Designing an IXP425 network processor-based residential gateway. It also invited, as usual, more than 400 journalists and industry analysts for briefings, including, not as usual, me. The attraction is the chance to cross-question top management, though it helps if you recognise them. At IDF, they all wear the same Intel blue shirts: it is not always obvious which ones are running multibillion dollar divisions.

Nor surprisingly, Intel focused on the forthcoming chips it wants IDF attendees to use in their forthcoming PCs. Most are Pentiums for notebook and desktop PCs, but the company also has the Xeon and Itanium 2 ranges for workstations and servers, the XScale (nee ARM) chips used in mobile phones and handheld computers such as HP's Compaq iPaq, plus the IXP425 network processor and other chips designed for communications.

Besides hyper-threading Pentiums, the next major launch will be Banias: the codename for a power-efficient version of the Pentium 4 designed from the ground up for "thin and light" internet-attached notebook PCs. Banias is expected to appear in the first quarter of next year, running at 1.4GHz. (Intel says "first half".) It should enable PC manufacturers to build standard notebooks that offer eight hours of battery life, which doesn't mean they will.

Anand Chandrasekher, general manager of Intel's mobile platforms group, says: "Banias is going to take over the majority of mobile platforms." Intel has also, he says, been collaborating with Microsoft and the Tablet PC manufacturers, and "we absolutely expect all of those designs will migrate to the Banias architecture." If all that happens, it will be bad news for Transmeta, which had hoped to find a niche for its Crusoe chips in the low-power market.

I ribbed Gelsinger, in our one-on-one, that HT and Banias made it look as though Intel was giving up on the megahertz race which, after all, could not go on much longer. He emphatically did not agree with that. "Paul [Otellini] showed a Pentium 4 running at 4.7GHz this morning," he said, "and within the next 10 years we'll have multibillion transistor chips operating in excess of 30GHz delivering 1 tera-instruction per second of performance within one piece of silicon. So we have a long way to go yet, and I believe it continues well past that." (Tera means 2 to the power of 40 or 1,099,511,627,776.)

One of the advantages of having billions of transistors on a chip is that you can have bigger cache memories. This means the processor can get data very quickly instead of waiting perhaps hundreds of clock cycles while it is fetched from slow main memory. "There is no end to the benefits of bigger caches in sight," says Gelsinger. "Another direction is chip-level multiprocessing, where you put multiple processors on a single die. But the big theme is not just thinking about transistors but thinking about applying silicon in new areas. Wireless - integrating radios into silicon; integrating photonics, and even integrating sensors into silicon. Further out, there are biological things you could think about integrating as well.

"But multi-threaded execution - chip-level multiprocessing - is the next big thing, which is why our hyper-threading announcement is such a big deal for the consumer desktop space. You get 30% extra performance and it doesn't cost you an extra penny. And this is just the beginning. What you're going to see us do with threaded machines in the future is dramatically beyond what we've announced today."