Intel's Flexible Return and Event Delivery (FRED) is a new CPU feature debuting with Panther Lake (Core Ultra Series 3) that overhauls privilege-level transitions for lower latency, more efficient NMI handling, and better performance under heavy I/O and network workloads. Despite being merged into the Linux kernel since version 6.9 in 2024, FRED is not enabled by default even on supported hardware through Linux 7.0. Benchmarks on a Core Ultra X7 358H laptop running Ubuntu 26.04 with Linux 7.0 show clear performance gains when manually enabling FRED via the 'fred=on' kernel boot parameter. The reason for the disabled-by-default status remains undocumented and unexplained by Intel. Users can check if FRED is active by searching for 'fred' in /proc/cpuinfo.
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