Documentation/scheduler/sched-eevdf.rst

9 of EEVDF proposed by Peter Zijlstra in 2023 [2-4]. More information
11 Documentation/scheduler/sched-design-CFS.rst.
13 Similarly to CFS, EEVDF aims to distribute CPU time equally among all
14 runnable tasks with the same priority. To do so, it assigns a virtual run
15 time to each task, creating a "lag" value that can be used to determine
16 whether a task has received its fair share of CPU time. In this way, a task
17 with a positive lag is owed CPU time, while a negative lag means the task
21 allows latency-sensitive tasks with shorter time slices to be prioritized,
25 tasks; but at the time of writing EEVDF uses a "decaying" mechanism based
26 on virtual run time (VRT). This prevents tasks from exploiting the system
28 remains on the run queue but marked for "deferred dequeue," allowing its
29 lag to decay over VRT. Hence, long-sleeping tasks eventually have their lag
31 can request specific time slices using the new sched_setattr() system call,
32 which further facilitates the job of latency-sensitive applications.
39 [2] https://lore.kernel.org/lkml/a79014e6-ea83-b316-1e12-2ae056bda6fa@linux.vnet.ibm.com/