forked from Imagelibrary/rtems
e8f4303a4c
* Makefile.am, configure.ac: Add support for proper stacking of priority inheritance on mutexes as well as enforce proper order of release. * sp36/.cvsignore, sp36/Makefile.am, sp36/sp36.doc, sp36/sp36.scn: New files.
43 lines
1.1 KiB
Plaintext
43 lines
1.1 KiB
Plaintext
This is a simple test program to demonstrate strict order mutex.
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1)What's strict order mutex ?
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In rtems,when a task release a priority_inheritance or
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priority ceiling semaphore,the kernel detect whether
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this task holds priority_inheritance or priority
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ceiling semaphore, if not, set the priority of task
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back to real priority of task.
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This method is right, but in theory, we would like
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to reset the priority after releasing the mutex if
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releasing it in LIFO order.Do it like this can decrease
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the blocking time of a higher priority task .
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2)How to enable "strict order mutex " ?
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When configuring the rtems , add
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ENABLE_STRICT_ORDER_MUTEX=1
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to your configure parameter.
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3)About this test program
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T0,T1,S0,S1
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T0,priority 4
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T1,priority 1
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S0,priority inheritance
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S1,priority ceiling,priority ceiling 1
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1,T0 obtain S0 then obtain S1, priority of T0 should be improved to 1
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2,T0 try to release S0, but not in strict order, return error code
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3,T0 release S1,the priority of T0 back to 4
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4,T1 try to obtain S0
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5,T1 should be blocked and the priority of T0 should be improved to 1
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6,T0 release S0
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7,T1 obtain S0
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8,OVER.
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