Completely Fair Scheduler (CFS)
Completely Fair Scheduler (CFS
TLDR: The Completely Fair Scheduler (CFS) is the default process scheduler in the Linux Kernel since 2007, introduced with Linux Kernel 2.6.23. It is designed to ensure fairness in CPU time allocation among processes, prioritizing efficiency and responsiveness. By employing a virtual runtime system, CFS ensures that each process receives CPU time proportional to its priority, making it a robust solution for multitasking.
https://en.wikipedia.org/wiki/Completely_Fair_Scheduler
The key innovation of CFS lies in its use of a red-black tree data structure to manage process scheduling. This structure enables CFS to track processes based on their virtual runtime, a metric that accounts for the time a process has used relative to its priority. Processes with the least virtual runtime are scheduled first, ensuring a balanced distribution of CPU resources. CFS replaces the earlier O(1) scheduler by providing a more scalable and flexible approach to scheduling.
https://www.kernel.org/doc/html/latest/scheduler/sched-design-CFS.html
CFS supports advanced features like priority classes, which differentiate between real-time and normal tasks. It is particularly effective in systems with mixed workloads, such as desktop environments and servers, where fairness and responsiveness are critical. Its ability to dynamically adjust scheduling decisions based on system demands makes CFS a cornerstone of modern Linux multitasking, contributing to the kernel's versatility and performance.
https://www.kernel.org/doc/html/latest/scheduler/sched-design-CFS-classes.html