x-glossary.html

vxworks相关论文

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<ul class="Dash" type="circle"><li><a name="89990"> </a>Periods of priority inheritance, shown as a striped line (<img class="figure" border="0" src="images/x-glossary5.gif">
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<dd><p class="Body"><a name="89992"> </a>See also event-logging level.</p>
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<h5 class="HU"><i><a name="89995">continuous upload mode</a></i></h5>
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<dd><p class="Body"><a name="89997"> </a>In this mode, the event buffer is initialized and the WindView upload task, <b class="task">tWVUpload</b>, is spawned. When event logging is active, event data is written to the dynamic ring buffer. When the buffer threshold is reached, <b class="task">tWVUpload</b> uploads the buffer's contents to the host. On the host, the event data is streamed to the WindView view graph, to a file, or to the <b class="command">evtRecv</b> tool. See also deferred upload mode and post-mortem mode.</p>
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<h5 class="HU"><i><a name="90004">Control window</a></i></h5>
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<dd><p class="Body"><a name="90005"> </a>The <b class="guiLabel"><font face="Helvetica, sans-serif" size="-1" class="sans">Control</font></b> window displays status information about the WindView configuration and WindView event logging. It also has a toolbar for controlling data collection and upload. </p>
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<h5 class="HU"><i><a name="90009">counting semaphore</a></i></h5>
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<dd><p class="Body"><a name="90011"> </a>A counting semaphore is similar to a binary semaphore except that it keeps track of the number of times the semaphore has been given. Every time the semaphore is given, the count is incremented; every time the semaphore is taken, the count is decremented. If the count reaches zero, any task that tries to take the semaphore makes a transition to the pended state.</p>
<dd><p class="Body"><a name="90016"> </a>Counting semaphores can be used for mutual exclusion and synchronization. They are most useful, however, in guarding resources of which there are multiple copies. For example, the use of five tape drives can be coordinated using a counting semaphore with an initial count of five. See also mutual exclusion semaphore.</p>
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<h5 class="HU"><i><a name="90021">CPU starvation</a></i></h5>
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<dd><p class="Body"><a name="90022"> </a>CPU starvation refers to a task that is "starving" for CPU time. In other words, the task never gets to run, because it is never the highest-priority ready task. This is a common bug in multitasking real-time systems, easily diagnosed with WindView. </p>
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<h5 class="HU"><i><a name="90029">cross-development</a></i></h5>
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<dd><p class="Body"><a name="90031"> </a>Cross-development is the development of an application on one platform (the host) for eventual execution on another platform (the target). This allows you to use the powerful host development resources, while minimizing the run-time effect on the target resources. For example, you might be developing a real-time application on a Windows NT workstation that when finished will run on a 68040 target board. Cross-development requires the use of special tools (such as cross compilers) that can handle this host versus target dichotomy.</p>
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<h5 class="HU"><i><a name="90035">CSE level </a></i></h5>
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<dd><p class="Body"><a name="90037"> </a>See <i class="term">context switch event-logging level</i>. </p>
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<h5 class="HU"><i><a name="90040">current context</a></i></h5>
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<dd><p class="Body"><a name="90042"> </a>In real-time systems, the term "current context" usually refers to the currently executing task and information needed to restore the task's state, such as the state of the processor registers, operating system control information, and the stack (see task context). For WindView, the meaning has been extended to include ISRs and the kernel's idle loop.</p>
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<h5 class="HU"><i><a name="90049">deadlock</a></i></h5>
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<dd><p class="Body"><a name="90052"> </a>Two or more tasks are in deadlock when they keep each other from running. For example, <b class="task">taskA</b> and <b class="task">taskB</b> are deadlocked when <b class="task">taskA</b> is pending on a semaphore waiting to be unblocked by <b class="task">taskB</b>, but <b class="task">taskB</b> is pending on another semaphore waiting to be unblocked by <b class="task">taskA</b>. This is a common bug in real-time systems, easily diagnosed with WindView. </p>
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<h5 class="HU"><i><a name="90056">dead state</a></i></h5>
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<dd><p class="Body"><a name="90058"> </a>A task is in the dead state if it has been deleted with the <b class="routine"><i class="routine">taskDelete</i></b><b>(&nbsp;)</b> or <b class="routine"><i class="routine">taskDeleteForce</i></b><b>(&nbsp;)</b> routine, or if it has exited. There is no stipple for this state, but users can define one if they wish to track it. See also task state, task state transition, deletion safety.</p>
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<h5 class="HU"><i><a name="90065">deferred upload mode</a></i></h5>
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<dd><p class="Body"><a name="90066"> </a>This is the default event-upload mode. In this mode, data is written to the dynamic ring buffer until the maximum number of buffers is full. Then data collection stops. Data is uploaded when the user requests it. See also continuous upload mode and post-mortem mode.</p>
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<h5 class="HU"><i><a name="90071">delayed state</a></i></h5>
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<dd><p class="Body"><a name="90077"> </a>A task is in the delayed state (shown by the <img class="figure" border="0" src="images/x-glossary6.gif">
 stipple) if it has been delayed with the <b class="routine"><i class="routine">taskDelay</i></b><b>(&nbsp;)</b> routine. See also task state, task state transition.</p>
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<h5 class="HU"><i><a name="90082">deletion safety</a></i></h5>
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<dd><p class="Body"><a name="90084"> </a>A task can make itself "safe" from deletion by other tasks by calling the <b class="routine"><i class="routine">taskSafe</i></b><b>(&nbsp;)</b> routine. This protection is often needed when a task executes in a critical region or engages a critical resource. Any task that attempts to delete a protected task makes a transition to the pended state. When finished with its critical resource, the protected task can make itself eligible for deletion by issuing <b class="routine"><i class="routine">taskUnsafe</i></b><b>(&nbsp;)</b>, which unblocks any deleting task. <b class="routine"><i class="routine">taskSafe</i></b><b>(&nbsp;)</b> routines can be nested; a task can only be deleted when the number of <b class="routine"><i class="routine">taskUnsafe</i></b><b>(&nbsp;)</b> routines equals the number of <b class="routine"><i class="routine">taskSafe</i></b><b>(&nbsp;)</b> routines. A task is also safe from deletion if it takes a mutual exclusion semaphore with the <b class="symbol_UC">SEM_DELETE_SAFE</b> option set. See also dead state.</p>
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<h5 class="HU"><i><a name="90096">download</a></i></h5>
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<dd><p class="Body"><a name="90098"> </a>Downloading refers to the transference of programs and data from the host to the target.</p>
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<dd><font face="Helvetica, sans-serif" size="-1" class="sans">
<h5 class="HU"><i><a name="90102">dynamic ring buffer</a></i></h5>
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<dd><p class="Body"><a name="90103"> </a>The dynamic ring buffer is a buffer ring that grows and shrinks dynamically between user-defined limits by adding or deleting buffers of user-specified size to the ring.</p>
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<h5 class="HU"><i><a name="90106">embedded system</a></i></h5>
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<dd><p class="Body"><a name="90107"> </a>An embedded system is a system built into a larger device that is dedicated to performing a specific task, such as a coffee maker or a satellite tracking system.</p>
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<h5 class="HU"><i><a name="90110">event</a></i></h5>
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<dd><p class="Body"><a name="90113"> </a>In WindView, an event is any action undertaken by a task or an ISR that can affect the state of the real-time system. Examples of events are semaphore gives and takes, task spawns and deletions, timer expirations, and interrupts. VxWorks has been instrumented to log this event information. See also event-logging level, instrumented code, user-generated events.</p>
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<dd><font face="Helvetica, sans-serif" size="-1" class="sans">
<h5 class="HU"><i><a name="90119">event buffer</a></i></h5>
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<dd><p class="Body"><a name="90121"> </a>The event buffer is a user-configurable area of memory on the target into which instrumented events are logged. In the default event upload mode (<i class="term">deferred mode</i>) when this buffer becomes full, data collection stops. In <i class="term">continuous mode</i>, when this buffer becomes full, its contents are uploaded to the host by the WindView upload task (<b class="task">tWVUpload</b>).</p>
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<dd><font face="Helvetica, sans-serif" size="-1" class="sans">
<h5 class="HU"><i><a name="90129">event data</a></i></h5>
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<dd><p class="Body"><a name="90131"> </a>This is information that is logged to the WindView event buffer. This data is uploaded to the host by the WindView upload task, <b class="task">tWVUpload</b>.</p>
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<dd><font face="Helvetica, sans-serif" size="-1" class="sans">
<h5 class="HU"><i><a name="90136">event data collection</a></i></h5>
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<dd><p class="Body"><a name="90139"> </a>This is the process of starting event logging on the VxWorks target, and then capturing the event data as it is uploaded to the host.</p>
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<h5 class="HU"><i><a name="90144">Event Dictionary</a></i></h5>
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<dd><p class="Body"><a name="90146"> </a>The event dictionary lists all possible events generated by WindView logging. It provides information about the circumstances under which the real-time system could generate each event, the icon associated with it, and the information logged. The event dictionary is available in the <i class="title"><a href="./index.html">WindView User's Guide</a></i> and in the online help. It can be reached online by selecting <b class="guiLabel"><font face="Helvetica, sans-serif" size="-1" class="sans">WindView Help&gt;Legend</font></b> in the main <b class="guiLabel"><font face="Helvetica, sans-serif" size="-1" class="sans">Help</font></b> menu, by selecting <b class="guiLabel"><font face="Helvetica, sans-serif" size="-1" class="sans">Help</font></b> in the WindView event pop-up menu, or by double-clicking on the appropriate item in the <b class="guiLabel"><font face="Helvetica, sans-serif" size="-1" class="sans">Legend</font></b> window.</p>
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<dd><font face="Helvetica, sans-serif" size="-1" class="sans">
<h5 class="HU"><i><a name="90152">event icon</a></i></h5>
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<dd><p class="Body"><a name="90154"> </a>Depending on the event-logging level that is specified, various icons are displayed in the view graph that correspond to events. For information on what each event icon represents, see the Legend window. To learn specific information on a particular instance of an icon, use the Show Event dialog box.</p>
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<dd><font face="Helvetica, sans-serif" size="-1" class="sans">
<h5 class="HU"><i><a name="90161">event log</a></i></h5>
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<dd><p class="Body"><a name="90163"> </a>An event log is a finite collection of event data that resides on the host. </p>
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<dd><font face="Helvetica, sans-serif" size="-1" class="sans">
<h5 class="HU"><i><a name="90166">event logging</a></i></h5>
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