Linux system bugs have affected the performance of AMD processors for 20 years

Linux system bugs have affected the performance of AMD processors for 20 years.

On Linux systems, people often find that some bugs will greatly affect the performance of current processors.

The old bugs found recently can even be traced back to 20 years ago, causing AMD’s current processor performance to decline in Linux. But Intel’s processors are not affected.

This problem was reported by AMD engineer K Prateek Nayak and is related to the fact that Linux systems began to support ACPI in 2002.

At that time, an operation dummy wait op was designed to deal with the problem that STPCLK# was not processed in time in some chipsets.

However, this process will Delay further instruction processing until the CPU is stopped.

This operation was fine on systems from many years ago, however on the latest generations of AMD processors, such as the Zen3 architecture Ryzen, this operation instruction causes severe performance degradation in some cases, especially when it comes to tbench loads.

This issue has affected AMD processors for years, but not Intel processors, whose platforms use a different code path instead.

The good news is that this problem will be fixed. AMD and Intel engineers have submitted new patches, and the above method is no longer used to deal with the problem.

The relevant patches have been merged into the Linux 6.0 kernel, and there will be no accidents in the future.