Lines Matching refs:time

44  "runtime" microseconds of execution time every "period" microseconds, and
47  every time the task wakes up, the scheduler computes a "scheduling deadline"
51  task actually receives "runtime" time units within "deadline" if a proper
60  with the "traditional" real-time task model (see Section 3) can effectively
77         scheduling deadline - current time           period
79     then, if the scheduling deadline is smaller than the current time, or
83          scheduling deadline = current time + deadline
89   - When a SCHED_DEADLINE task executes for an amount of time t, its
98     said to be "throttled" (also known as "depleted" in real-time literature)
100     time" for this task (see next item) is set to be equal to the current
103   - When the current time is equal to the replenishment time of a
126  suited for periodic or sporadic real-time tasks that need guarantees on their
129  A typical real-time task is composed of a repetition of computation phases
133  arrival time r_j (the time when the job starts), an amount of computation
134  time c_j needed to finish the job, and a job absolute deadline d_j, which
135  is the time within which the job should be finished. The maximum execution
136  time max_j{c_j} is called "Worst Case Execution Time" (WCET) for the task.
137  A real-time task can be periodic with period P if r_{j+1} = r_j + P, or
138  sporadic with minimum inter-arrival time P is r_{j+1} >= r_j + P. Finally,
140  The utilisation of a real-time task is defined as the ratio between its
141  WCET and its period (or minimum inter-arrival time), and represents
142  the fraction of CPU time needed to execute the task.
148  WCET_i/P_i over all the real-time tasks in the system. When considering
149  multiple real-time tasks, the parameters of the i-th task are indicated
152  non- real-time tasks by real-time tasks.
153  If, instead, the total utilisation is smaller than M, then non real-time
158  between the finishing time of a job and its absolute deadline).
166  real-time task is statically assigned to one and only one CPU), it is
182  than M is enough to guarantee that non real-time tasks are not starved and
183  that the tardiness of real-time tasks has an upper bound.
185  SCHED_DEADLINE can be used to schedule real-time tasks guaranteeing that
202       ming in a hard-real-time environment. Journal of the Association for
205       Real-Time Systems. Proceedings of the 19th IEEE Real-time Systems
214  effective and useful (that is, to be able to provide "runtime" time units
216  of the available fractions of CPU time to the various tasks under control.
221  correctly schedule a set of real-time tasks is that the total utilisation
225  of a "traditional" real-time task, and is also often referred to as
229  tasks with real-time group scheduling (a.k.a. RT-throttling - see
241  only used at admission control time (i.e., when the user calls
276   - a (maximum/typical) instance execution time,
278   - a time constraint by which each instance must be completed.
294  This means that non -deadline tasks will receive at least 5% of the CPU time,
406  showing how SCHED_DEADLINE reservations can be created by a real-time
414  #include <time.h>