Last month I ran benchmarks showing the very positive performance impact FRED has on Intel's new Panther Lake processors while wondering why Flexible Return and Event Deliver wasn't enabled by default yet on Linux. Hours after that story was published, an Intel engineer posted the patch to enable FRED by default with the rationale they were waiting for hardware to be publicly released in order to evaluate the performance benefit. Days after that the FRED-by-default patch hit tip/tip.git and now as of yesterday that patch is merged for Linux 7.1.

What this means for Intel Core Ultra Series 3 "Panther Lake" users on Linux is better performance when moving to Linux 7.1+ -- assuming you aren't already booting your existing kernel with the manual fred=on option for enabling this functionality. As the FRED benchmarks showed there can be nice gains for I/O tasks including various database software, in-memory key-value stores, networking applications, digital signal processing and digital audio processing applications, some graphics/gaming software, and much more.

This merge is what provides FRED by default on Linux 7.1. The merge message was:

"We made the FRED support an opt-in initially out of fear of it breaking machines left and right in the case of a hw bug in the first generation of machines supporting it.

Now that that the FRED code has seen a lot of hammering, flip the logic to be opt-out as is the usual case with new hw features."

Great news for Panther Lake on Linux and pairs nicely with the Panther Lake intel_idle driver C-state additions for Linux 7.1 as well as ongoing Xe kernel graphics driver improvements and other enhancements to the mainline kernel via Intel engineers.

FRED is also expected to be used by upcoming AMD Zen 6 processors as well as Intel Xeon Diamond Rapids server processors, among other future Intel/AMD CPUs.