Documentation/scheduler/sched-deadline.rst

2 Deadline Task Scheduling
9     2. Scheduling algorithm
12     3. Scheduling Real-Time Tasks
33  system behavior. As for -rt (group) scheduling, it is assumed that root users
40  The SCHED_DEADLINE policy contained inside the sched_dl scheduling class is
41  basically an implementation of the Earliest Deadline First (EDF) scheduling
46 2. Scheduling algorithm
57  every time the task wakes up, the scheduler computes a "scheduling deadline"
59  scheduled using EDF[1] on these scheduling deadlines (the task with the
60  earliest scheduling deadline is selected for execution). Notice that the
65  Summing up, the CBS[2,3] algorithm assigns scheduling deadlines to tasks so
68  algorithm selects the task with the earliest scheduling deadline as the one
73  In more details, the CBS algorithm assigns scheduling deadlines to
79   - The state of the task is described by a "scheduling deadline", and
87         scheduling deadline - current time           period
89     then, if the scheduling deadline is smaller than the current time, or
90     this condition is verified, the scheduling deadline and the
93          scheduling deadline = current time + deadline
96     otherwise, the scheduling deadline and the remaining runtime are
109     and cannot be scheduled until its scheduling deadline. The "replenishment
111     value of the scheduling deadline;
114     throttled task, the scheduling deadline and the remaining runtime are
117          scheduling deadline = scheduling deadline + period
286 2.3 Energy-aware scheduling
299 3. Scheduling Real-Time Tasks
309    scheduling theory, and how it applies to SCHED_DEADLINE.
311    how the scheduling policy can be used. Anyway, we strongly recommend
318  scheduling discipline, even if it must be said that it is particularly
371  If M=1 (uniprocessor system), or in case of partitioned scheduling (each
416  On multiprocessor systems with global EDF scheduling (non partitioned
449  about schedulability tests for multi-processor real-time scheduling can be
454  (in other words, global EDF is not an optimal scheduling algorithm). However,
467  SCHED_DEADLINE scheduling parameters described in Section 2 (runtime,
471  SCHED_DEADLINE schedules the tasks according to scheduling deadlines (see
473  If an admission test is used to guarantee that the scheduling deadlines
482  IOW, if runtime >= WCET and if period is <= P, then the scheduling deadlines
491   1 - C. L. Liu and J. W. Layland. Scheduling algorithms for multiprogram-
499   4 - J. Y. Leung and M.L. Merril. A Note on Preemptive Scheduling of
502   5 - S. K. Baruah, A. K. Mok and L. E. Rosier. Preemptively Scheduling
506       Concerning the Preemptive Scheduling of Periodic Real-Time tasks on
509   7 - S. J. Dhall and C. L. Liu. On a real-time scheduling problem. Operations
516   10 - J. Goossens, S. Funk and S. Baruah, Priority-Driven Scheduling of
519   11 - R. Davis and A. Burns. A Survey of Hard Real-Time Scheduling for
523        Scheduling on a Multiprocessor. Real-Time Systems Journal, vol. 32,
540   18 - J. Lelli, C. Scordino, L. Abeni, D. Faggioli, Deadline scheduling in the
543   19 - C. Scordino, L. Abeni, J. Lelli, Energy-Aware Real-Time Scheduling in
551  As previously mentioned, in order for -deadline scheduling to be
556  no guarantee can be given on the actual scheduling of the -deadline tasks.
567  tasks with real-time group scheduling (a.k.a. RT-throttling - see
580  sched_setattr()). Scheduling is then performed considering actual tasks'
623   * the new scheduling related syscalls that manipulate it, i.e.,
642  and the cpuset mechanism is used to implement partitioned scheduling (see
704   - (c)group based bandwidth management, and maybe scheduling;
723  SCHED_{OTHER,FIFO,RR,DEADLINE} scheduling policies and their related