Which CPU Does a Woken Task Run On? Understanding wake_affine and select_idle_sibling

The article explains how the Linux kernel decides the CPU for a newly woken task, detailing the roles of wake_affine and select_idle_sibling, the influence of cache topology, run‑queue load, and various idle‑checking heuristics, with concrete examples and code snippets.

CPU affinityLinux kernelTask Scheduling

0 likes · 9 min read

Which CPU Does a Woken Task Run On? Understanding wake_affine and select_idle_sibling

Linux Code Review Hub

Mar 30, 2025 · Fundamentals

Where Does a Woken Task Run? Exploring wake_affine and select_idle_sibling in the Linux Scheduler

The article analyzes how the Linux kernel decides the CPU for a task that has just been woken, detailing the roles of wake_affine and select_idle_sibling, and examining factors such as cache affinity, idle status, load, and hardware topology that influence the final placement.

CPU affinitykernelselect_idle_sibling

0 likes · 9 min read

Where Does a Woken Task Run? Exploring wake_affine and select_idle_sibling in the Linux Scheduler