Intel's fifth-generation Xeon Emerald Rapids series CPUs are set to launch in December 2023. Recently, a small patch has pushed their performance to new heights.

Canonical engineer Pedro Henrique Kopper submitted a patch to the Linux Kernel Mailing List (LKML) titled "Update Balance performance EPP for Emerald Rapids."

This seemingly minor adjustment is an optimization of the EPP (Energy Performance Preference) value, which has significantly improved the performance and energy efficiency of Intel's data center CPUs.

By default, the EPP value in balanced performance mode is 128. However, in a joint internal investigation with Intel, the team found that setting the EPP value to 32 is more appropriate.

This change not only boosts performance but also maintains better energy efficiency. Specifically, this adjustment brings significant improvements in the following areas:

• POV-Ray rendering speed increased by 32% with a 12% reduction in energy consumption

• OpenSSL encryption speed increased by 12% with energy consumption changing within 1%

• Building a Linux kernel was 29% faster with an 18% reduction in energy consumption

Pedro recommends changing the default EPP value in balanced performance mode to 32, consistent with changes made last year to Sapphire Rapids, when a simple one-line code patch brought significant performance improvements.

It is worth noting that this performance improvement and power reduction only affect the default balanced performance mode in Ubuntu Linux and other Linux-based operating systems.

Users switching to modes such as "Performance" will not experience these optimizations, but even so, an EPP value of 32 can still save more power than 128.

Linux PM maintainer Rafael Wysocki expects to implement the patch for the Linux 6.11 kernel in a week or two.