AMD Phenom TLB patch - massive performance hit

Posted on Thursday, Dec 06 2007 @ 12:58 CET by Thomas De Maesschalck
The Tech Report really is the main source if you want to learn about the TLB erratum that is plaguing AMD. The site just got their hands on a BIOS update which features a microcode update workaround for the problem and ran some benchmarks to see how bad the patch affects the performance.
This week's developments have included the revelation that this bug affects all "Barcelona" quad-core Opterons, leading to a "stop ship" order on quad-core Opterons to most customers. The erratum also affects all speed grades of Phenom processors, which are still shipping to PC makers and resellers. AMD admitted the presence of the erratum prior to the Phenom's public introduction, but the firm's initial statements gave many the impression that the erratum affected only the 2.4GHz version of the Phenom, which it had decided to delay. In truth, all current Phenom variants have the bug, and systems with those processors will have to be patched and suffer the accompanying performance penalty.

One thing we haven't known is exactly how that performance penalty would look—until today. We can now offer you some preliminary benchmarks that demonstrate the impact of the BIOS-based workaround for the problem.
You can check it out over here. The results don't look pretty for AMD. The Phenom didn't really have impressive performance to begin with and The Tech Report found that the TLB patch drops the performance by an average of 19.8% in their benchmark suite. If they rule out synthetic memory tests the difference drops to 13.9% but that's still a massive performance hit.

If you really want a Phenom processor you should wait until the B3 revision arrives but that means you'll have to keep your money in your pocket for at least a couple of months as the B3 Phenoms are expected in mid-to-late Q1 2008. Hopefully the firm will have their act together by then.

About the Author

Thomas De Maesschalck

Thomas has been messing with computer since early childhood and firmly believes the Internet is the best thing since sliced bread. Enjoys playing with new tech, is fascinated by science, and passionate about financial markets. When not behind a computer, he can be found with running shoes on or lifting heavy weights in the weight room.

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