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Diffstat (limited to 'doc/user/rtmon.t')
| -rw-r--r-- | doc/user/rtmon.t | 65 |
1 files changed, 58 insertions, 7 deletions
diff --git a/doc/user/rtmon.t b/doc/user/rtmon.t index da9e2de2cf..3e2dbeeab8 100644 --- a/doc/user/rtmon.t +++ b/doc/user/rtmon.t @@ -14,6 +14,9 @@ @chapter Rate Monotonic Manager +@cindex rate mononitonic tasks +@cindex periodic tasks + @section Introduction The rate monotonic manager provides facilities to @@ -46,6 +49,8 @@ A clock tick is required to support the functionality provided by this manager. @subsection Rate Monotonic Manager Definitions +@cindex periodic task, definition + A periodic task is one which must be executed at a regular interval. The interval between successive iterations of the task is referred to as its period. Periodic tasks can be @@ -61,12 +66,16 @@ the execution time may be the average, worst, or best case, the worst-case execution time is more appropriate for use when analyzing system behavior under transient overload conditions. +@cindex aperiodic task, definition + In contrast, an aperiodic task executes at irregular intervals and has only a soft deadline. In other words, the deadlines for aperiodic tasks are not rigid, but adequate response times are desirable. For example, an aperiodic task may process user input from a terminal. +@cindex sporadic task, definition + Finally, a sporadic task is an aperiodic task with a hard deadline and minimum interarrival time. The minimum interarrival time is the minimum period of time which exists @@ -78,6 +87,9 @@ but the missile must be launched by a hard deadline. @subsection Rate Monotonic Scheduling Algorithm +@cindex Rate Monotonic Scheduling Algorithm, definition +@cindex RMS Algorithm, definition + The Rate Monotonic Scheduling Algorithm (RMS) is important to real-time systems designers because it allows one to guarantee that a set of tasks is schedulable. A set of tasks @@ -196,6 +208,8 @@ schedulability is only guaranteed for the critical task set. @subsection Schedulability Analysis +@cindex RMS schedulability analysis + RMS allows application designers to insure that tasks can meet all deadlines, even under transient overload, without knowing exactly when any given task will execute by applying @@ -233,6 +247,8 @@ side-effects accounted for. @subsection Processor Utilization Rule +@cindex RMS Processor Utilization Rule + The Processor Utilization Rule requires that processor utilization be calculated based upon the period and execution time of each task. The fraction of processor time @@ -347,6 +363,8 @@ this task set is guaranteed to be schedulable using RMS. @subsection First Deadline Rule +@cindex RMS First Deadline Rule + If a given set of tasks do exceed the processor utilization upper limit imposed by the Processor Utilization Rule, they can still be guaranteed to meet all their deadlines @@ -828,13 +846,18 @@ directives. A subsection is dedicated to each of this manager's directives and describes the calling sequence, related constants, usage, and status codes. +@c +@c +@c @page @subsection RATE_MONOTONIC_CREATE - Create a rate monotonic period +@cindex create a period + @subheading CALLING SEQUENCE: @ifset is-C -@c @findex rtems_rate_monotonic_create +@findex rtems_rate_monotonic_create @example rtems_status_code rtems_rate_monotonic_create( rtems_name name, @@ -872,13 +895,19 @@ initializes it. This directive will not cause the calling task to be preempted. +@c +@c +@c @page @subsection RATE_MONOTONIC_IDENT - Get ID of a period +@cindex get ID of a period +@cindex obtain ID of a period + @subheading CALLING SEQUENCE: @ifset is-C -@c @findex rtems_rate_monotonic_ident +@findex rtems_rate_monotonic_ident @example rtems_status_code rtems_rate_monotonic_ident( rtems_name name, @@ -915,13 +944,18 @@ access this period in other rate monotonic manager directives. This directive will not cause the running task to be preempted. +@c +@c +@c @page @subsection RATE_MONOTONIC_CANCEL - Cancel a period +@cindex cancel a period + @subheading CALLING SEQUENCE: @ifset is-C -@c @findex rtems_rate_monotonic_cancel +@findex rtems_rate_monotonic_cancel @example rtems_status_code rtems_rate_monotonic_cancel( rtems_id id @@ -957,13 +991,18 @@ preempted. The rate monotonic period specified by id must have been created by the calling task. +@c +@c +@c @page @subsection RATE_MONOTONIC_DELETE - Delete a rate monotonic period +@cindex delete a period + @subheading CALLING SEQUENCE: @ifset is-C -@c @findex rtems_rate_monotonic_delete +@findex rtems_rate_monotonic_delete @example rtems_status_code rtems_rate_monotonic_delete( rtems_id id @@ -998,13 +1037,20 @@ preempted. A rate monotonic period can be deleted by a task other than the task which created the period. +@c +@c +@c @page @subsection RATE_MONOTONIC_PERIOD - Conclude current/Start next period +@cindex conclude current period +@cindex start current period +@cindex period initiation + @subheading CALLING SEQUENCE: @ifset is-C -@c @findex rtems_rate_monotonic_period +@findex rtems_rate_monotonic_period @example rtems_status_code rtems_rate_monotonic_period( rtems_id id, @@ -1049,14 +1095,19 @@ the state or period of the period. This directive will not cause the running task to be preempted. ---------------------- +@c +@c +@c @page @subsection RATE_MONOTONIC_GET_STATUS - Obtain status information on period +@cindex get status of period +@cindex obtain status of period + @subheading CALLING SEQUENCE: @ifset is-C -@c @findex rtems_rate_monotonic_get_status +@findex rtems_rate_monotonic_get_status @example rtems_status_code rtems_rate_monotonic_get_status( rtems_id id, |