Lines Matching refs:time

48  "runtime" microseconds of execution time every "period" microseconds, and
51  every time the task wakes up, the scheduler computes a "scheduling deadline"
55  task actually receives "runtime" time units within "deadline" if a proper
64  with the "traditional" real-time task model (see Section 3) can effectively
81         scheduling deadline - current time           period
83     then, if the scheduling deadline is smaller than the current time, or
87          scheduling deadline = current time + deadline
93   - When a SCHED_DEADLINE task executes for an amount of time t, its
102     said to be "throttled" (also known as "depleted" in real-time literature)
104     time" for this task (see next item) is set to be equal to the current
107   - When the current time is equal to the replenishment time of a
130  suited for periodic or sporadic real-time tasks that need guarantees on their
136  A typical real-time task is composed of a repetition of computation phases
140  arrival time r_j (the time when the job starts), an amount of computation
141  time c_j needed to finish the job, and a job absolute deadline d_j, which
142  is the time within which the job should be finished. The maximum execution
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
145  sporadic with minimum inter-arrival time P is r_{j+1} >= r_j + P. Finally,
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
151  WCET and its period (or minimum inter-arrival time), and represents
152  the fraction of CPU time needed to execute the task.
158  WCET_i/P_i over all the real-time tasks in the system. When considering
159  multiple real-time tasks, the parameters of the i-th task are indicated
162  non- real-time tasks by real-time tasks.
163  If, instead, the total utilization is smaller than M, then non real-time
168  between the finishing time of a job and its absolute deadline).
180  real-time task is statically assigned to one and only one CPU), it is
195  (Task_1 is scheduled as soon as it is released, and finishes just in time
197  its response time cannot be larger than 50ms + 10ms = 60ms) even if
203  computing the total amount of CPU time h(t) needed by all the tasks to
204  respect all of their deadlines in a time interval of size t, and comparing
205  such a time with the interval size t. If h(t) is smaller than t (that is,
206  the amount of time needed by the tasks in a time interval of size t is
214  time-consuming to be performed on-line. Hence, as explained in Section
229  arbitrarily small worst case execution time (indicated as "e" here) and a
231  activate at the same time t, global EDF schedules these M tasks first
234  result, Task_1 can be scheduled only at time t + e, and will finish at
235  time t + e + P, after its absolute deadline. The total utilization of the
243  real-time literature[8,9], but they are not based on a simple comparison
251  about schedulability tests for multi-processor real-time scheduling can be
257  a total utilization smaller than M is enough to guarantee that non real-time
258  tasks are not starved and that the tardiness of real-time tasks has an upper
260  experienced by real-time tasks have been developed in various papers[13,14],
270  deadline and period) and the real-time task parameters (WCET, D, P)
276  are respected, then SCHED_DEADLINE can be used to schedule real-time tasks
293       ming in a hard-real-time environment. Journal of the Association for
296       Real-Time Systems. Proceedings of the 19th IEEE Real-time Systems
305       11th IEEE Real-time Systems Symposium, 1990.
310   7 - S. J. Dhall and C. L. Liu. On a real-time scheduling problem. Operations
338  effective and useful (that is, to be able to provide "runtime" time units
340  of the available fractions of CPU time to the various tasks under control.
345  correctly schedule a set of real-time tasks is that the total utilization
349  of a "traditional" real-time task, and is also often referred to as
353  tasks with real-time group scheduling (a.k.a. RT-throttling - see
365  only used at admission control time (i.e., when the user calls
400   - a (maximum/typical) instance execution time,
402   - a time constraint by which each instance must be completed.
418  This means that non -deadline tasks will receive at least 5% of the CPU time,
530  showing how SCHED_DEADLINE reservations can be created by a real-time
538  #include <time.h>