[489740f] | 1 | .. comment SPDX-License-Identifier: CC-BY-SA-4.0 |
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| 2 | |
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[0d86b71] | 3 | .. COMMENT: COPYRIGHT (c) 1989-2011. |
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| 4 | .. COMMENT: On-Line Applications Research Corporation (OAR). |
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| 5 | .. COMMENT: All rights reserved. |
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| 6 | |
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[3384994] | 7 | .. index:: cbs |
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| 8 | |
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[fd6dc8c8] | 9 | Constant Bandwidth Server Scheduler API |
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[4da4a15] | 10 | *************************************** |
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[fd6dc8c8] | 11 | |
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| 12 | Introduction |
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| 13 | ============ |
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| 14 | |
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[0d86b71] | 15 | Unlike simple schedulers, the Constant Bandwidth Server (CBS) requires a |
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| 16 | special API for tasks to indicate their scheduling parameters. The directives |
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| 17 | provided by the CBS API are: |
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[fd6dc8c8] | 18 | |
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[0d86b71] | 19 | - rtems_cbs_initialize_ - Initialize the CBS library |
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[fd6dc8c8] | 20 | |
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[0d86b71] | 21 | - rtems_cbs_cleanup_ - Cleanup the CBS library |
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[fd6dc8c8] | 22 | |
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[0d86b71] | 23 | - rtems_cbs_create_server_ - Create a new bandwidth server |
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[fd6dc8c8] | 24 | |
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[0d86b71] | 25 | - rtems_cbs_attach_thread_ - Attach a thread to server |
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[fd6dc8c8] | 26 | |
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[0d86b71] | 27 | - rtems_cbs_detach_thread_ - Detach a thread from server |
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[fd6dc8c8] | 28 | |
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[0d86b71] | 29 | - rtems_cbs_destroy_server_ - Destroy a bandwidth server |
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[fd6dc8c8] | 30 | |
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[0d86b71] | 31 | - rtems_cbs_get_server_id_ - Get an ID of a server |
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[fd6dc8c8] | 32 | |
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[0d86b71] | 33 | - rtems_cbs_get_parameters_ - Get scheduling parameters of a server |
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[fd6dc8c8] | 34 | |
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[0d86b71] | 35 | - rtems_cbs_set_parameters_ - Set scheduling parameters of a server |
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[fd6dc8c8] | 36 | |
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[0d86b71] | 37 | - rtems_cbs_get_execution_time_ - Get elapsed execution time |
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[fd6dc8c8] | 38 | |
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[0d86b71] | 39 | - rtems_cbs_get_remaining_budget_ - Get remainig execution time |
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[fd6dc8c8] | 40 | |
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[0d86b71] | 41 | - rtems_cbs_get_approved_budget_ - Get scheduler approved execution time |
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[fd6dc8c8] | 42 | |
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[6c56401] | 43 | .. index:: CBS parameters |
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| 44 | .. index:: rtems_cbs_parameters |
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[fd6dc8c8] | 45 | |
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[3384994] | 46 | Background |
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| 47 | ========== |
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| 48 | |
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[fd6dc8c8] | 49 | Constant Bandwidth Server Definitions |
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| 50 | ------------------------------------- |
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| 51 | |
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[0d86b71] | 52 | The Constant Bandwidth Server API enables tasks to communicate with the |
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| 53 | scheduler and indicate its scheduling parameters. The scheduler has to be set |
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| 54 | up first (by defining ``CONFIGURE_SCHEDULER_CBS`` macro). |
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| 55 | |
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| 56 | The difference to a plain EDF is the presence of servers. It is a budget aware |
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| 57 | extention of the EDF scheduler, therefore, tasks attached to servers behave in |
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| 58 | a similar way as with EDF unless they exceed their budget. |
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| 59 | |
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| 60 | The intention of servers is reservation of a certain computation time (budget) |
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| 61 | of the processor for all subsequent periods. The structure |
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| 62 | ``rtems_cbs_parameters`` determines the behavior of a server. It contains |
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| 63 | ``deadline`` which is equal to period, and ``budget`` which is the time the |
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| 64 | server is allowed to spend on CPU per each period. The ratio between those two |
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| 65 | parameters yields the maximum percentage of the CPU the server can use |
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| 66 | (bandwidth). Moreover, thanks to this limitation the overall utilization of CPU |
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| 67 | is under control, and the sum of bandwidths of all servers in the system yields |
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| 68 | the overall reserved portion of processor. The rest is still available for |
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| 69 | ordinary tasks that are not attached to any server. |
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| 70 | |
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| 71 | In order to make the server effective to the executing tasks, tasks have to be |
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| 72 | attached to the servers. The ``rtems_cbs_server_id`` is a type denoting an id |
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| 73 | of a server and ``rtems_id`` a type for id of tasks. |
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[6c56401] | 74 | .. index:: CBS periodic tasks |
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[fd6dc8c8] | 75 | |
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| 76 | Handling Periodic Tasks |
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| 77 | ----------------------- |
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| 78 | |
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[0d86b71] | 79 | Each task's execution begins with a default background priority (see the |
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| 80 | chapter Scheduling Concepts to understand the concept of priorities in |
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| 81 | EDF). Once you decide the tasks should start periodic execution, you have two |
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| 82 | possibilities. Either you use only the Rate Monotonic manager which takes care |
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| 83 | of periodic behavior, or you declare deadline and budget using the CBS API in |
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| 84 | which case these properties are constant for all subsequent periods, unless you |
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| 85 | change them using the CBS API again. Task now only has to indicate and end of |
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[fd6dc8c8] | 86 | each period using ``rtems_rate_monotonic_period``. |
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[6c56401] | 87 | .. index:: CBS overrun handler |
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[fd6dc8c8] | 88 | |
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| 89 | Registering a Callback Function |
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| 90 | ------------------------------- |
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| 91 | |
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[0d86b71] | 92 | In case tasks attached to servers are not aware of their execution time and |
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| 93 | happen to exceed it, the scheduler does not guarantee execution any more and |
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| 94 | pulls the priority of the task to background, which would possibly lead to |
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| 95 | immediate preemption (if there is at least one ready task with a higher |
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| 96 | pirority). However, the task is not blocked but a callback function is |
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| 97 | invoked. The callback function (``rtems_cbs_budget_overrun``) might be |
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| 98 | optionally registered upon a server creation (``rtems_cbs_create_server``). |
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[fd6dc8c8] | 99 | |
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| 100 | This enables the user to define what should happen in case of budget |
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[0d86b71] | 101 | overrun. There is obviously no space for huge operations because the priority |
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| 102 | is down and not real time any more, however, you still can at least in release |
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| 103 | resources for other tasks, restart the task or log an error information. Since |
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| 104 | the routine is called directly from kernel, use ``printk()`` instead of |
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| 105 | ``printf()``. |
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| 106 | |
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| 107 | The calling convention of the callback function is: |
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[fd6dc8c8] | 108 | |
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[0d86b71] | 109 | .. index:: rtems_asr |
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[fd6dc8c8] | 110 | |
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[0d86b71] | 111 | .. code-block:: c |
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[fd6dc8c8] | 112 | |
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| 113 | void overrun_handler( |
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[0d86b71] | 114 | rtems_cbs_server_id server_id |
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[fd6dc8c8] | 115 | ); |
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[6c56401] | 116 | .. index:: CBS limitations |
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[fd6dc8c8] | 117 | |
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| 118 | Limitations |
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| 119 | ----------- |
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| 120 | |
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| 121 | When using this scheduler you have to keep in mind several things: |
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| 122 | |
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| 123 | - it_limitations |
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| 124 | |
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[0d86b71] | 125 | - In the current implementation it is possible to attach only a single task to |
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| 126 | each server. |
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[fd6dc8c8] | 127 | |
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[0d86b71] | 128 | - If you have a task attached to a server and you voluntatily block it in the |
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| 129 | beginning of its execution, its priority will be probably pulled to |
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| 130 | background upon unblock, thus not guaranteed deadline any more. This is |
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| 131 | because you are effectively raising computation time of the task. When |
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| 132 | unbocking, you should be always sure that the ratio between remaining |
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| 133 | computation time and remaining deadline is not higher that the utilization |
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| 134 | you have agreed with the scheduler. |
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[fd6dc8c8] | 135 | |
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| 136 | Operations |
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| 137 | ========== |
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| 138 | |
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| 139 | Setting up a server |
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| 140 | ------------------- |
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| 141 | |
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[0d86b71] | 142 | The directive ``rtems_cbs_create_server`` is used to create a new server that |
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| 143 | is characterized by ``rtems_cbs_parameters``. You also might want to register |
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| 144 | the ``rtems_cbs_budget_overrun`` callback routine. After this step tasks can be |
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| 145 | attached to the server. The directive ``rtems_cbs_set_parameters`` can change |
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| 146 | the scheduling parameters to avoid destroying and creating a new server again. |
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[fd6dc8c8] | 147 | |
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| 148 | Attaching Task to a Server |
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| 149 | -------------------------- |
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| 150 | |
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[0d86b71] | 151 | If a task is attached to a server using ``rtems_cbs_attach_thread``, the task's |
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| 152 | computation time per period is limited by the server and the deadline (period) |
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| 153 | of task is equal to deadline of the server which means if you conclude a period |
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| 154 | using ``rate_monotonic_period``, the length of next period is always determined |
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| 155 | by the server's property. |
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[fd6dc8c8] | 156 | |
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[0d86b71] | 157 | The task has a guaranteed bandwidth given by the server but should not exceed |
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| 158 | it, otherwise the priority is pulled to background until the start of next |
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| 159 | period and the ``rtems_cbs_budget_overrun`` callback function is invoked. |
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[fd6dc8c8] | 160 | |
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[0d86b71] | 161 | When attaching a task to server, the preemptability flag of the task is raised, |
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| 162 | otherwise it would not be possible to control the execution of the task. |
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[fd6dc8c8] | 163 | |
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| 164 | Detaching Task from a Server |
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| 165 | ---------------------------- |
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| 166 | |
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[0d86b71] | 167 | The directive ``rtems_cbs_detach_thread`` is just an inverse operation to the |
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| 168 | previous one, the task continues its execution with the initial priority. |
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[fd6dc8c8] | 169 | |
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| 170 | Preemptability of the task is restored to the initial value. |
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| 171 | |
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| 172 | Examples |
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| 173 | -------- |
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| 174 | |
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| 175 | The following example presents a simple common use of the API. |
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| 176 | |
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[0d86b71] | 177 | You can see the initialization and cleanup call here, if there are multiple |
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| 178 | tasks in the system, it is obvious that the initialization should be called |
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| 179 | before creating the task. |
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[fd6dc8c8] | 180 | |
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| 181 | Notice also that in this case we decided to register an overrun handler, |
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[0d86b71] | 182 | instead of which there could be ``NULL``. This handler just prints a message to |
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| 183 | terminal, what else may be done here depends on a specific application. |
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[fd6dc8c8] | 184 | |
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[0d86b71] | 185 | During the periodic execution, remaining budget should be watched to avoid |
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| 186 | overrun. |
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| 187 | |
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| 188 | .. code-block:: c |
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[fd6dc8c8] | 189 | |
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| 190 | void overrun_handler ( |
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[0d86b71] | 191 | rtems_cbs_server_id server_id |
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[fd6dc8c8] | 192 | ) |
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| 193 | { |
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[0d86b71] | 194 | printk( "Budget overrun, fixing the task\\n" ); |
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| 195 | return; |
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[fd6dc8c8] | 196 | } |
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[0d86b71] | 197 | |
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[fd6dc8c8] | 198 | rtems_task Tasks_Periodic( |
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[0d86b71] | 199 | rtems_task_argument argument |
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[fd6dc8c8] | 200 | ) |
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| 201 | { |
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[0d86b71] | 202 | rtems_id rmid; |
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| 203 | rtems_cbs_server_id server_id; |
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| 204 | rtems_cbs_parameters params; |
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| 205 | |
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| 206 | params.deadline = 10; |
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| 207 | params.budget = 4; |
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| 208 | |
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| 209 | rtems_cbs_initialize(); |
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| 210 | rtems_cbs_create_server( ¶ms, &overrun_handler, &server_id ) |
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| 211 | rtems_cbs_attach_thread( server_id, SELF ); |
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| 212 | rtems_rate_monotonic_create( argument, &rmid ); |
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| 213 | |
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| 214 | while ( 1 ) { |
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| 215 | if (rtems_rate_monotonic_period(rmid, params.deadline) == RTEMS_TIMEOUT) |
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| 216 | break; |
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[36def91] | 217 | /* Perform some periodic action */ |
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[0d86b71] | 218 | } |
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| 219 | |
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| 220 | rtems_rate_monotonic_delete( rmid ); |
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| 221 | rtems_cbs_cleanup(); |
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| 222 | exit( 1 ); |
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[fd6dc8c8] | 223 | } |
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| 224 | |
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| 225 | Directives |
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| 226 | ========== |
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| 227 | |
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[0d86b71] | 228 | This section details the Constant Bandwidth Server's directives. A subsection |
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| 229 | is dedicated to each of this manager's directives and describes the calling |
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| 230 | sequence, related constants, usage, and status codes. |
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| 231 | |
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[53bb72e] | 232 | .. raw:: latex |
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| 233 | |
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| 234 | \clearpage |
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| 235 | |
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[6c56401] | 236 | .. index:: initialize the CBS library |
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| 237 | .. index:: rtems_cbs_initialize |
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[3384994] | 238 | .. _rtems_cbs_initialize: |
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[fd6dc8c8] | 239 | |
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| 240 | CBS_INITIALIZE - Initialize the CBS library |
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| 241 | ------------------------------------------- |
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| 242 | |
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[53bb72e] | 243 | CALLING SEQUENCE: |
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| 244 | .. code-block:: c |
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[fd6dc8c8] | 245 | |
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[53bb72e] | 246 | int rtems_cbs_initialize( void ); |
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[fd6dc8c8] | 247 | |
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[53bb72e] | 248 | DIRECTIVE STATUS CODES: |
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| 249 | .. list-table:: |
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| 250 | :class: rtems-table |
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[fd6dc8c8] | 251 | |
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[53bb72e] | 252 | * - ``RTEMS_CBS_OK`` |
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| 253 | - successful initialization |
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| 254 | * - ``RTEMS_CBS_ERROR_NO_MEMORY`` |
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| 255 | - not enough memory for data |
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[0d86b71] | 256 | |
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[53bb72e] | 257 | DESCRIPTION: |
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| 258 | This routine initializes the library in terms of allocating necessary |
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| 259 | memory for the servers. In case not enough memory is available in the |
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| 260 | system, ``RTEMS_CBS_ERROR_NO_MEMORY`` is returned, otherwise |
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| 261 | ``RTEMS_CBS_OK``. |
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[fd6dc8c8] | 262 | |
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[53bb72e] | 263 | NOTES: |
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| 264 | Additional memory per each server is allocated upon invocation of |
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| 265 | ``rtems_cbs_create_server``. |
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[fd6dc8c8] | 266 | |
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[53bb72e] | 267 | Tasks in the system are not influenced, they still keep executing with |
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| 268 | their initial parameters. |
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[fd6dc8c8] | 269 | |
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[53bb72e] | 270 | .. raw:: latex |
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[fd6dc8c8] | 271 | |
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[53bb72e] | 272 | \clearpage |
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[0d86b71] | 273 | |
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[6c56401] | 274 | .. index:: cleanup the CBS library |
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| 275 | .. index:: rtems_cbs_cleanup |
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[fd6dc8c8] | 276 | |
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[3384994] | 277 | .. _rtems_cbs_cleanup: |
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| 278 | |
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[fd6dc8c8] | 279 | CBS_CLEANUP - Cleanup the CBS library |
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| 280 | ------------------------------------- |
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| 281 | |
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[53bb72e] | 282 | CALLING SEQUENCE: |
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| 283 | .. code-block:: c |
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[fd6dc8c8] | 284 | |
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[53bb72e] | 285 | int rtems_cbs_cleanup( void ); |
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[fd6dc8c8] | 286 | |
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[53bb72e] | 287 | DIRECTIVE STATUS CODES: |
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| 288 | .. list-table:: |
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| 289 | :class: rtems-table |
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[fd6dc8c8] | 290 | |
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[53bb72e] | 291 | * - ``RTEMS_CBS_OK`` |
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| 292 | - always successful |
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[0d86b71] | 293 | |
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[53bb72e] | 294 | DESCRIPTION: |
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| 295 | This routine detaches all tasks from their servers, destroys all servers |
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| 296 | and returns memory back to the system. |
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[fd6dc8c8] | 297 | |
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[53bb72e] | 298 | NOTES: |
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| 299 | All tasks continue executing with their initial priorities. |
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[fd6dc8c8] | 300 | |
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[53bb72e] | 301 | .. raw:: latex |
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[fd6dc8c8] | 302 | |
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[53bb72e] | 303 | \clearpage |
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[fd6dc8c8] | 304 | |
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[6c56401] | 305 | .. index:: create a new bandwidth server |
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| 306 | .. index:: rtems_cbs_create_server |
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[0d86b71] | 307 | |
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[3384994] | 308 | .. _rtems_cbs_create_server: |
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| 309 | |
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[fd6dc8c8] | 310 | CBS_CREATE_SERVER - Create a new bandwidth server |
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| 311 | ------------------------------------------------- |
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| 312 | |
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[53bb72e] | 313 | CALLING SEQUENCE: |
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| 314 | .. code-block:: c |
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| 315 | |
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| 316 | int rtems_cbs_create_server ( |
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| 317 | rtems_cbs_parameters *params, |
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| 318 | rtems_cbs_budget_overrun budget_overrun_callback, |
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| 319 | rtems_cbs_server_id *server_id |
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| 320 | ); |
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| 321 | |
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| 322 | DIRECTIVE STATUS CODES: |
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| 323 | .. list-table:: |
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| 324 | :class: rtems-table |
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| 325 | |
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| 326 | * - ``RTEMS_CBS_OK`` |
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| 327 | - successfully created |
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| 328 | * - ``RTEMS_CBS_ERROR_NO_MEMORY`` |
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| 329 | - not enough memory for data |
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| 330 | * - ``RTEMS_CBS_ERROR_FULL`` |
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| 331 | - maximum servers exceeded |
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| 332 | * - ``RTEMS_CBS_ERROR_INVALID_PARAMETER`` |
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| 333 | - invalid input argument |
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| 334 | |
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| 335 | DESCRIPTION: |
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| 336 | This routine prepares an instance of a constant bandwidth server. The |
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| 337 | input parameter ``rtems_cbs_parameters`` specifies scheduling parameters of |
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| 338 | the server (period and budget). If these are not valid, |
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| 339 | ``RTEMS_CBS_ERROR_INVALID_PARAMETER`` is returned. The |
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| 340 | ``budget_overrun_callback`` is an optional callback function, which is |
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| 341 | invoked in case the server's budget within one period is exceeded. Output |
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| 342 | parameter ``server_id`` becomes an id of the newly created server. If |
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| 343 | there is not enough memory, the ``RTEMS_CBS_ERROR_NO_MEMORY`` is |
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| 344 | returned. If the maximum server count in the system is exceeded, |
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| 345 | ``RTEMS_CBS_ERROR_FULL`` is returned. |
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| 346 | |
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| 347 | NOTES: |
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| 348 | No task execution is being influenced so far. |
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| 349 | |
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| 350 | .. raw:: latex |
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| 351 | |
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| 352 | \clearpage |
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[fd6dc8c8] | 353 | |
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[6c56401] | 354 | .. index:: attach a thread to server |
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| 355 | .. index:: rtems_cbs_attach_thread |
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[0d86b71] | 356 | |
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[3384994] | 357 | .. _rtems_cbs_attach_thread: |
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| 358 | |
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[fd6dc8c8] | 359 | CBS_ATTACH_THREAD - Attach a thread to server |
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| 360 | --------------------------------------------- |
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| 361 | |
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[53bb72e] | 362 | CALLING SEQUENCE: |
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| 363 | .. code-block:: c |
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[fd6dc8c8] | 364 | |
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[53bb72e] | 365 | int rtems_cbs_attach_thread ( |
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| 366 | rtems_cbs_server_id server_id, |
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| 367 | rtems_id task_id |
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| 368 | ); |
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[fd6dc8c8] | 369 | |
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[53bb72e] | 370 | DIRECTIVE STATUS CODES: |
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| 371 | .. list-table:: |
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| 372 | :class: rtems-table |
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[fd6dc8c8] | 373 | |
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[53bb72e] | 374 | * - ``RTEMS_CBS_OK`` |
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| 375 | - successfully attached |
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| 376 | * - ``RTEMS_CBS_ERROR_FULL`` |
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| 377 | - server maximum tasks exceeded |
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| 378 | * - ``RTEMS_CBS_ERROR_INVALID_PARAMETER`` |
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| 379 | - invalid input argument |
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| 380 | * - ``RTEMS_CBS_ERROR_NOSERVER`` |
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| 381 | - server is not valid |
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[0d86b71] | 382 | |
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[53bb72e] | 383 | DESCRIPTION: |
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| 384 | Attaches a task (``task_id``) to a server (``server_id``). The server has |
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| 385 | to be previously created. Now, the task starts to be scheduled according to |
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| 386 | the server parameters and not using initial priority. This implementation |
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| 387 | allows only one task per server, if the user tries to bind another task to |
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| 388 | the same server, ``RTEMS_CBS_ERROR_FULL`` is returned. |
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[fd6dc8c8] | 389 | |
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[53bb72e] | 390 | NOTES: |
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| 391 | Tasks attached to servers become preemptible. |
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[fd6dc8c8] | 392 | |
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[53bb72e] | 393 | .. raw:: latex |
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[fd6dc8c8] | 394 | |
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[53bb72e] | 395 | \clearpage |
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[fd6dc8c8] | 396 | |
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[6c56401] | 397 | .. index:: detach a thread from server |
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| 398 | .. index:: rtems_cbs_detach_thread |
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[0d86b71] | 399 | |
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[3384994] | 400 | .. _rtems_cbs_detach_thread: |
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| 401 | |
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[fd6dc8c8] | 402 | CBS_DETACH_THREAD - Detach a thread from server |
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| 403 | ----------------------------------------------- |
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| 404 | |
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[53bb72e] | 405 | CALLING SEQUENCE: |
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| 406 | .. code-block:: c |
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[fd6dc8c8] | 407 | |
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[53bb72e] | 408 | int rtems_cbs_detach_thread ( |
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| 409 | rtems_cbs_server_id server_id, |
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| 410 | rtems_id task_id |
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| 411 | ); |
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[fd6dc8c8] | 412 | |
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[53bb72e] | 413 | DIRECTIVE STATUS CODES: |
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| 414 | .. list-table:: |
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| 415 | :class: rtems-table |
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[0d86b71] | 416 | |
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[53bb72e] | 417 | * - ``RTEMS_CBS_OK`` |
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| 418 | - successfully detached |
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| 419 | * - ``RTEMS_CBS_ERROR_INVALID_PARAMETER`` |
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| 420 | - invalid input argument |
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| 421 | * - ``RTEMS_CBS_ERROR_NOSERVER`` |
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| 422 | - server is not valid |
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[fd6dc8c8] | 423 | |
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[53bb72e] | 424 | DESCRIPTION: |
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| 425 | This directive detaches a thread from server. The task continues its |
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| 426 | execution with initial priority. |
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[fd6dc8c8] | 427 | |
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[53bb72e] | 428 | NOTES: |
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| 429 | The server can be reused for any other task. |
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[fd6dc8c8] | 430 | |
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[53bb72e] | 431 | .. raw:: latex |
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[fd6dc8c8] | 432 | |
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[53bb72e] | 433 | \clearpage |
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[fd6dc8c8] | 434 | |
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[6c56401] | 435 | .. index:: destroy a bandwidth server |
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| 436 | .. index:: rtems_cbs_destroy_server |
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[0d86b71] | 437 | |
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[3384994] | 438 | .. _rtems_cbs_destroy_server: |
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| 439 | |
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[fd6dc8c8] | 440 | CBS_DESTROY_SERVER - Destroy a bandwidth server |
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| 441 | ----------------------------------------------- |
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| 442 | |
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[53bb72e] | 443 | CALLING SEQUENCE: |
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| 444 | .. code-block:: c |
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[fd6dc8c8] | 445 | |
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[53bb72e] | 446 | int rtems_cbs_destroy_server ( |
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| 447 | rtems_cbs_server_id server_id |
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| 448 | ); |
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[fd6dc8c8] | 449 | |
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[53bb72e] | 450 | DIRECTIVE STATUS CODES: |
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| 451 | .. list-table:: |
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| 452 | :class: rtems-table |
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[fd6dc8c8] | 453 | |
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[53bb72e] | 454 | * - ``RTEMS_CBS_OK`` |
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| 455 | - successfully destroyed |
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| 456 | * - ``RTEMS_CBS_ERROR_INVALID_PARAMETER`` |
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| 457 | - invalid input argument |
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| 458 | * - ``RTEMS_CBS_ERROR_NOSERVER`` |
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| 459 | - server is not valid |
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[0d86b71] | 460 | |
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[53bb72e] | 461 | DESCRIPTION: |
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| 462 | This directive destroys a server. If any task was attached to the server, |
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| 463 | the task is detached and continues its execution according to EDF rules |
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| 464 | with initial properties. |
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[fd6dc8c8] | 465 | |
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[53bb72e] | 466 | NOTES: |
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| 467 | This again enables one more task to be created. |
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[fd6dc8c8] | 468 | |
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[53bb72e] | 469 | .. raw:: latex |
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[fd6dc8c8] | 470 | |
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[53bb72e] | 471 | \clearpage |
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[fd6dc8c8] | 472 | |
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[6c56401] | 473 | .. index:: get an ID of a server |
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| 474 | .. index:: rtems_cbs_get_server_id |
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[0d86b71] | 475 | |
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[3384994] | 476 | .. _rtems_cbs_get_server_id: |
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| 477 | |
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[fd6dc8c8] | 478 | CBS_GET_SERVER_ID - Get an ID of a server |
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| 479 | ----------------------------------------- |
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| 480 | |
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[53bb72e] | 481 | CALLING SEQUENCE: |
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| 482 | .. code-block:: c |
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[fd6dc8c8] | 483 | |
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[53bb72e] | 484 | int rtems_cbs_get_server_id ( |
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| 485 | rtems_id task_id, |
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| 486 | rtems_cbs_server_id *server_id |
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| 487 | ); |
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[fd6dc8c8] | 488 | |
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[53bb72e] | 489 | DIRECTIVE STATUS CODES: |
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| 490 | .. list-table:: |
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| 491 | :class: rtems-table |
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[fd6dc8c8] | 492 | |
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[53bb72e] | 493 | * - ``RTEMS_CBS_OK`` |
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| 494 | - successful |
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| 495 | * - ``RTEMS_CBS_ERROR_NOSERVER`` |
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| 496 | - server is not valid |
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[0d86b71] | 497 | |
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[53bb72e] | 498 | DESCRIPTION: |
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| 499 | This directive returns an id of server belonging to a given task. |
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[fd6dc8c8] | 500 | |
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[53bb72e] | 501 | .. raw:: latex |
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[fd6dc8c8] | 502 | |
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[53bb72e] | 503 | \clearpage |
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[fd6dc8c8] | 504 | |
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[6c56401] | 505 | .. index:: get scheduling parameters of a server |
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| 506 | .. index:: rtems_cbs_get_parameters |
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[0d86b71] | 507 | |
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[3384994] | 508 | .. _rtems_cbs_get_parameters: |
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| 509 | |
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[fd6dc8c8] | 510 | CBS_GET_PARAMETERS - Get scheduling parameters of a server |
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| 511 | ---------------------------------------------------------- |
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| 512 | |
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[53bb72e] | 513 | CALLING SEQUENCE: |
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| 514 | .. code-block:: c |
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[fd6dc8c8] | 515 | |
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[53bb72e] | 516 | rtems_cbs_get_parameters ( |
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| 517 | rtems_cbs_server_id server_id, |
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| 518 | rtems_cbs_parameters *params |
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| 519 | ); |
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[fd6dc8c8] | 520 | |
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[53bb72e] | 521 | DIRECTIVE STATUS CODES: |
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| 522 | .. list-table:: |
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| 523 | :class: rtems-table |
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[0d86b71] | 524 | |
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[53bb72e] | 525 | * - ``RTEMS_CBS_OK`` |
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| 526 | - successful |
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| 527 | * - ``RTEMS_CBS_ERROR_INVALID_PARAMETER`` |
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| 528 | - invalid input argument |
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| 529 | * - ``RTEMS_CBS_ERROR_NOSERVER`` |
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| 530 | - server is not valid |
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[fd6dc8c8] | 531 | |
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[53bb72e] | 532 | DESCRIPTION: |
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| 533 | This directive returns a structure with current scheduling parameters of a |
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| 534 | given server (period and execution time). |
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[fd6dc8c8] | 535 | |
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[53bb72e] | 536 | NOTES: |
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| 537 | It makes no difference if any task is assigned or not. |
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[fd6dc8c8] | 538 | |
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[53bb72e] | 539 | .. raw:: latex |
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[fd6dc8c8] | 540 | |
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[53bb72e] | 541 | \clearpage |
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[fd6dc8c8] | 542 | |
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[6c56401] | 543 | .. index:: set scheduling parameters |
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| 544 | .. index:: rtems_cbs_set_parameters |
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[0d86b71] | 545 | |
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[3384994] | 546 | .. _rtems_cbs_set_parameters: |
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| 547 | |
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[fd6dc8c8] | 548 | CBS_SET_PARAMETERS - Set scheduling parameters |
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| 549 | ---------------------------------------------- |
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| 550 | |
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[53bb72e] | 551 | CALLING SEQUENCE: |
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| 552 | .. code-block:: c |
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[fd6dc8c8] | 553 | |
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[53bb72e] | 554 | int rtems_cbs_set_parameters ( |
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| 555 | rtems_cbs_server_id server_id, |
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| 556 | rtems_cbs_parameters *params |
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| 557 | ); |
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[fd6dc8c8] | 558 | |
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[53bb72e] | 559 | DIRECTIVE STATUS CODES: |
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| 560 | .. list-table:: |
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| 561 | :class: rtems-table |
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[0d86b71] | 562 | |
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[53bb72e] | 563 | * - ``RTEMS_CBS_OK`` |
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| 564 | - successful |
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| 565 | * - ``RTEMS_CBS_ERROR_INVALID_PARAMETER`` |
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| 566 | - invalid input argument |
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| 567 | * - ``RTEMS_CBS_ERROR_NOSERVER`` |
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| 568 | - server is not valid |
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[fd6dc8c8] | 569 | |
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[53bb72e] | 570 | DESCRIPTION: |
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| 571 | This directive sets new scheduling parameters to the server. This operation |
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| 572 | can be performed regardless of whether a task is assigned or not. If a |
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| 573 | task is assigned, the parameters become effective imediately, therefore it |
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| 574 | is recommended to apply the change between two subsequent periods. |
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[fd6dc8c8] | 575 | |
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[53bb72e] | 576 | NOTES: |
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| 577 | There is an upper limit on both period and budget equal to (2^31)-1 ticks. |
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[fd6dc8c8] | 578 | |
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[53bb72e] | 579 | .. raw:: latex |
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[fd6dc8c8] | 580 | |
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[53bb72e] | 581 | \clearpage |
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[fd6dc8c8] | 582 | |
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[6c56401] | 583 | .. index:: get elapsed execution time |
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| 584 | .. index:: rtems_cbs_get_execution_time |
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[0d86b71] | 585 | |
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[3384994] | 586 | .. _rtems_cbs_get_execution_time: |
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| 587 | |
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[fd6dc8c8] | 588 | CBS_GET_EXECUTION_TIME - Get elapsed execution time |
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| 589 | --------------------------------------------------- |
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| 590 | |
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[53bb72e] | 591 | CALLING SEQUENCE: |
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| 592 | .. code-block:: c |
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[fd6dc8c8] | 593 | |
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[53bb72e] | 594 | int rtems_cbs_get_execution_time ( |
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| 595 | rtems_cbs_server_id server_id, |
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| 596 | time_t *exec_time, |
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| 597 | time_t *abs_time |
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| 598 | ); |
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[fd6dc8c8] | 599 | |
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[53bb72e] | 600 | DIRECTIVE STATUS CODES: |
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| 601 | .. list-table:: |
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| 602 | :class: rtems-table |
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[fd6dc8c8] | 603 | |
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[53bb72e] | 604 | * - ``RTEMS_CBS_OK`` |
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| 605 | - successful |
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| 606 | * - ``RTEMS_CBS_ERROR_INVALID_PARAMETER`` |
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| 607 | - invalid input argument |
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| 608 | * - ``RTEMS_CBS_ERROR_NOSERVER`` |
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| 609 | - server is not valid |
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[0d86b71] | 610 | |
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[53bb72e] | 611 | DESCRIPTION: |
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| 612 | This routine returns consumed execution time (``exec_time``) of a server |
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| 613 | during the current period. |
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[fd6dc8c8] | 614 | |
---|
[53bb72e] | 615 | NOTES: |
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| 616 | Absolute time (``abs_time``) not supported now. |
---|
[fd6dc8c8] | 617 | |
---|
[53bb72e] | 618 | .. raw:: latex |
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[fd6dc8c8] | 619 | |
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[53bb72e] | 620 | \clearpage |
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[fd6dc8c8] | 621 | |
---|
[6c56401] | 622 | .. index:: get remaining execution time |
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| 623 | .. index:: rtems_cbs_get_remaining_budget |
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[0d86b71] | 624 | |
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[3384994] | 625 | .. _rtems_cbs_get_remaining_budget: |
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| 626 | |
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[fd6dc8c8] | 627 | CBS_GET_REMAINING_BUDGET - Get remaining execution time |
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| 628 | ------------------------------------------------------- |
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| 629 | |
---|
[53bb72e] | 630 | CALLING SEQUENCE: |
---|
| 631 | .. code-block:: c |
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[fd6dc8c8] | 632 | |
---|
[53bb72e] | 633 | int rtems_cbs_get_remaining_budget ( |
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| 634 | rtems_cbs_server_id server_id, |
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| 635 | time_t *remaining_budget |
---|
| 636 | ); |
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[fd6dc8c8] | 637 | |
---|
[53bb72e] | 638 | DIRECTIVE STATUS CODES: |
---|
| 639 | .. list-table:: |
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| 640 | :class: rtems-table |
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[0d86b71] | 641 | |
---|
[53bb72e] | 642 | * - ``RTEMS_CBS_OK`` |
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| 643 | - successful |
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| 644 | * - ``RTEMS_CBS_ERROR_INVALID_PARAMETER`` |
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| 645 | - invalid input argument |
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| 646 | * - ``RTEMS_CBS_ERROR_NOSERVER`` |
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| 647 | - server is not valid |
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[fd6dc8c8] | 648 | |
---|
[53bb72e] | 649 | DESCRIPTION: |
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| 650 | This directive returns remaining execution time of a given server for |
---|
| 651 | current period. |
---|
[fd6dc8c8] | 652 | |
---|
[53bb72e] | 653 | NOTES: |
---|
| 654 | If the execution time approaches zero, the assigned task should finish |
---|
| 655 | computations of the current period. |
---|
[fd6dc8c8] | 656 | |
---|
[53bb72e] | 657 | .. raw:: latex |
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[fd6dc8c8] | 658 | |
---|
[53bb72e] | 659 | \clearpage |
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[fd6dc8c8] | 660 | |
---|
[6c56401] | 661 | .. index:: get scheduler approved execution time |
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| 662 | .. index:: rtems_cbs_get_approved_budget |
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[0d86b71] | 663 | |
---|
[3384994] | 664 | .. _rtems_cbs_get_approved_budget: |
---|
| 665 | |
---|
[fd6dc8c8] | 666 | CBS_GET_APPROVED_BUDGET - Get scheduler approved execution time |
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| 667 | --------------------------------------------------------------- |
---|
| 668 | |
---|
[53bb72e] | 669 | CALLING SEQUENCE: |
---|
| 670 | .. code-block:: c |
---|
[fd6dc8c8] | 671 | |
---|
[53bb72e] | 672 | int rtems_cbs_get_approved_budget ( |
---|
| 673 | rtems_cbs_server_id server_id, |
---|
| 674 | time_t *appr_budget |
---|
| 675 | ); |
---|
[0d86b71] | 676 | |
---|
[53bb72e] | 677 | DIRECTIVE STATUS CODES: |
---|
| 678 | .. list-table:: |
---|
| 679 | :class: rtems-table |
---|
[fd6dc8c8] | 680 | |
---|
[53bb72e] | 681 | * - ``RTEMS_CBS_OK`` |
---|
| 682 | - successful |
---|
| 683 | * - ``RTEMS_CBS_ERROR_INVALID_PARAMETER`` |
---|
| 684 | - invalid input argument |
---|
| 685 | * - ``RTEMS_CBS_ERROR_NOSERVER`` |
---|
| 686 | - server is not valid |
---|
[fd6dc8c8] | 687 | |
---|
[53bb72e] | 688 | DESCRIPTION: |
---|
| 689 | This directive returns server's approved budget for subsequent periods. |
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