Lines Matching refs:task

47  "deadline", to schedule tasks. A SCHED_DEADLINE task should receive
51  every time the task wakes up, the scheduler computes a "scheduling deadline"
53  scheduled using EDF[1] on these scheduling deadlines (the task with the
55  task actually receives "runtime" time units within "deadline" if a proper
60  that each task runs for at most its runtime every period, avoiding any
62  algorithm selects the task with the earliest scheduling deadline as the one
64  with the "traditional" real-time task model (see Section 3) can effectively
70   - Each SCHED_DEADLINE task is characterized by the "runtime",
73   - The state of the task is described by a "scheduling deadline", and
76   - When a SCHED_DEADLINE task wakes up (becomes ready for execution),
93   - When a SCHED_DEADLINE task executes for an amount of time t, its
99     task is descheduled / preempted);
101   - When the remaining runtime becomes less or equal than 0, the task is
104     time" for this task (see next item) is set to be equal to the current
108     throttled task, the scheduling deadline and the remaining runtime are
128  There are no limitations on what kind of task can exploit this new
136  A typical real-time task is composed of a repetition of computation phases
137  (task instances, or jobs) which are activated on a periodic or sporadic
139  Each job J_j (where J_j is the j^th job of the task) is characterized by an
143  time max{c_j} is called "Worst Case Execution Time" (WCET) for the task.
144  A real-time task can be periodic with period P if r_{j+1} = r_j + P, or
146  d_j = r_j + D, where D is the task's relative deadline.
147  Summing up, a real-time task can be described as
150  The utilization of a real-time task is defined as the ratio between its
152  the fraction of CPU time needed to execute the task.
159  multiple real-time tasks, the parameters of the i-th task are indicated
170  maximum tardiness of each task is smaller or equal than
180  real-time task is statically assigned to one and only one CPU), it is
185  If D_i != P_i for some task, then it is possible to define the density of
186  a task as WCET_i/min{D_i,P_i}, and EDF is able to respect all the deadlines
191  necessary: there are task sets that are schedulable, but do not respect the
192  condition. For example, consider the task set {Task_1,Task_2} composed by
222  utilizations or densities: it can be shown that even if D_i = P_i task
227  CPUs, with the first task Task_1=(P,P,P) having period, relative deadline
230  period smaller than the one of the first task. Hence, if all the tasks
236  task set is U = M · e / (P - 1) + P / P = M · e / (P - 1) + 1, and for small
270  deadline and period) and the real-time task parameters (WCET, D, P)
277  guaranteeing that all the jobs' deadlines of a task are respected.
278  In order to do this, a task must be scheduled by setting:
286  allows to respect the jobs' absolute deadlines for this task (this is what is
289  this task, as it is not possible to respect its temporal constraints.
349  of a "traditional" real-time task, and is also often referred to as
358  figure out how we want to manage SCHED_DEADLINE bandwidth at the task group
397  Specifying a periodic/sporadic task that executes for a given amount of
427  -deadline task cannot fork.
439  An example of a simple configuration (pin a -deadline task to CPU0)
440  follows (rt-app is used to create a -deadline task).
454  task affinity)