Heat Got You Down? Double Up

There are certain physical laws that sometimes limit what one can do. At least, that's true until technology finds a solution to what had been a conundrum. A good example is the so-called "sound barrier." The "sound barrier" turned out to be no barrier at all once there was sufficient power available in aircraft engines, and airframe designs had been modified to handle the buffeting at trans-sonic speeds.

But in processor performance, we're coming up to a decision point. As processors get faster and faster, the heat they generate is making other alternatives seem more attractive.

Power dissipation in processors varies directly with frequency: As frequency goes up, so does the power the chip uses, and that means it gets hotter. So if you want to increase performance, heat becomes more of a problem. "We can get some performance gains with increasing clock speeds," says Intel spokesman Howard High, "but there are some other engineering challenges. As frequency goes up, so does heat. You have to manage it."

Well, users, and that means IT folks who want their servers to go faster, demand more performance. So both Intel and AMD are now talking about making dual-core X86-code-based processors that will boost performance at nominal clock-speed increases, rather than relying only on higher clock speeds.

"If you can end up with two processors instead of one in each CPU socket, then you can get the ability to perform tasks in less time," says Barry Crume, a director in the server and workstation segment for AMD.It's the same basic idea as using multiple processors in a server, of course. In the multiprocessor case, two (or more) separate packaged processors go on the motherboard to increase performance. With dual-core processors, you wind up with two processor cores inside one package on the motherboard. So you double the capability of the package. More than that, because the interconnects are all so short, inter-core communication takes place essentially at the clock rate, so bus speeds are not a bottleneck.

Of course, things had to happen on the software side to make dual-core processing something worth doing. "Today's operating systems are now multi-tasking," explains Crume. "So you can get an instant performance boost on executables that are running under a multi-tasking OS."

But in addition, many applications running on servers today are multi-threaded, which means they can run operations in parallel if more than one processor is available to do the work. "In the server and the workstation space, the OS and a large proportion of the applications are multi-threaded, so the opportunity is there to take advantage of dual-core technology."

So what will happen when these companies offer the dual-core processors? Well, the performance gains promise to be impressive. High says that in the case of multi-threaded applications and OS, you should be able to see some performance gains in the range of 50 to 60 percent, just by putting a dual-core processor into the mix. Crume says it can be better than that: He predicts performance gains of 25 to 90 percent, under the right circumstances. Your results may vary, of course.

We should point out that dual-core processors are already here, in the case of RISC processors. But AMD and Intel are now taking dual-core processors into the x86 world. AMD has announced that it has a design taped out, while Intel has announced the intention to bring these products out. "You'll see the first from us next year," says Intel's High. AMD's Crume is also talking about next year as a time frame, and he says that there will be further announcements as developments occur. In this way, he says, large system OEMs and the software community can get ready for this next technology step.David Gabel has been testing and writing about computers for more than 25 years.