Silicon Valley Watcher - Former FT journalist Tom Foremski reporting from the intersection of technology and media

Multi-Core Microprocessors Break the Software Performance Gains of Moore's Law

Posted by Tom Foremski - September 10, 2007

43512A Quadcore Grn 120X90 Advanced Micro Devices Monday unveiled its quad-core Opteron server chip also known as “Barcelona.” It is an impressive chip designed for server applications and featuring four-processor cores plus several electric power-saving technologies.

AMD is hoping that Barcelona will help it build on the success of its Opteron server family. And it has lined up hardware partners such as IBM, Sun, HP, Dell, Cray and many others.

Bruce Shaw, director of worldwide commercial and enterprise marketing said, “Data centers that face space and power constraints are prime customers for Barcelona based servers, they can provide more computing for less power.” The chips can switch off large sections when not in use and without causing any lag in performance.

The new chip has been criticized for not being as fast as rival chips. It operates at 2 GHz. However, the clock speed of the chip is a poor measure of overall system performance.

“The type of memory used in the system makes a big difference on power consumption and performance,” says Mr Shaw. The AMD chip offers faster access to memory than in rival Intel chips, and it supports types of low-power consuming memory chips.

The biggest challenge, in terms of driving performance for AMD and Intel's multi-core chips, comes from the software industry.

Both companies make use of Moore's Law which doubles the number of transistors on a chip about every 18 to 24 months. Chip makers have consistently been able to push their production process to keep up with Moore's Law. And by doing so, software automatically runs faster on their latest chips.

Moore's Law and Software Performance

However, with multi-core microprocessors, the automatic performance increases due to Moore's Law start to quickly diminish. That's because the vast majority of software is designed to run on a single processor. Developers would need to rewrite their software to spread the work across two or more cores in order to gain the performance benefits of multi-core processors.

Margaret Lewis, director of Commercial Solutions at AMD, says it is a problem. “My job is to work with the software development community to educate them on developing applications for multi-core microprocessors. But these techniques have to be taught in the beginning, in the classroom, so that developers naturally think about how to create parallel processing within their software.”

Sometimes using compilers and operating systems can help spread the load of an application across several cores. But these offer incremental improvements compared with writing software for multi-core environments. “There are quite a few issues to deal with, such as having the right development tools. Also, debugging the software is more complicated.”

Ms Lewis doesn't believe in a technology breakthrough. “I don't think there is one silver bullet, this is a difficult problem. The solution will come from many smaller silver bullets.” Collecting those silver bullets will take years. In the meantime, Moore's Law will help create 8, 16, and 32 core processors, but the free ride for software developers is over.

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Overview from AMD: http://multicore.amd.com/us-en/AMD-Multi-Core.aspx

Review: AMD's New Quad Core Barcelona

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