Changeset 29e6637e in rtems for doc/user/glossary.texi

May 5, 2014, 7:55:13 PM (7 years ago)
Sebastian Huber <sebastian.huber@…>
4.11, 5, master
Sebastian Huber <sebastian.huber@…> (05/05/14 19:55:13)
Sebastian Huber <sebastian.huber@…> (05/08/14 06:43:45)

doc: Move SMP glossary to global glossary

Add some terms.

1 edited


  • doc/user/glossary.texi

    rd9196d1d r29e6637e  
    3333manager are used to service signals.
     35@item atomic operations
     36Atomic operations are defined in terms of @cite{ISO/IEC 9899:2011}.
    3538@item awakened
    3639A term used to describe a task that has
    5053A physically contiguous area of memory.
    52 @item blocked
    53 The task state entered by a task which has
    54 been previously started and cannot continue execution until the
    55 reason for waiting has been satisfied.
     55@item blocked task
     56The task state entered by a task which has been previously started and cannot
     57continue execution until the reason for waiting has been satisfied.  Blocked
     58tasks are not an element of the set of ready tasks of a scheduler instance.
    5760@item broadcast
    8790array in that it is not limited to a predefined size.
     92@item cluster
     93We have clustered scheduling in case the set of processors of a system is
     94partitioned into non-empty pairwise disjoint subsets.  These subsets are called
     95@dfn{clusters}.  Each cluster is owned by exactly one scheduler instance.
    8997@item coalesce
    9098The process of merging adjacent holes into
    186194A synonym for interrupt.
    188 @item executing
    189 The task state entered by a task after it
    190 has been given control of the CPU.
     196@item executing task
     197The task state entered by a task after it has been given control of the
     198processor.  On SMP configurations a task may be registered as executing on more
     199than one processor for short time frames during task migration.  Blocked tasks
     200can be executing until they issue a thread dispatch.
    192202@item executive
    220230A resource that has been released by the
    221231application to RTEMS.
     233@item Giant lock
     234The @dfn{Giant lock} is a recursive SMP lock protecting most parts of the
     235operating system state.  Virtually every operating system service must acquire
     236and release the Giant lock during its operation.
    223238@item global
    243258and deallocate variable sized blocks of memory.
     260@item heir task
     261A task is an @dfn{heir} if it is registered as an heir in a processor of the
     262system.  A task can be the heir on at most one processor in the system.  In
     263case the executing and heir tasks differ on a processor and a thread dispatch
     264is marked as necessary, then the next thread dispatch will make the heir task
     265the executing task.
    245267@item heterogeneous
    246268A multiprocessor computer system composed of dissimilar processors.
    256278A special low priority task which assumes
    257279control of the CPU when no other task is able to execute.
     281@item in the air task
     282A task is @dfn{in the air} if it is in a transient state and has a processor
     283assigned.  The next scheduler operation will turn it into a blocked, ready or
     284scheduled task.  This state is specific to SMP configurations.
    259286@item interface
    436463and deallocate fixed size blocks of memory from an dynamically
    437464specified area of memory.
     466@item partition
     467Clusters with a cardinality of one are @dfn{partitions}.
    439469@item Partition Control Block
    523553An acronym for Message Queue Control Block.
    525 @item ready
    526 A task occupies this state when it is
    527 available to be given control of the CPU.
     555@item ready task
     556A task occupies this state when it is available to be given control of a
     557processor.  A ready task has no processor assigned.  The scheduler decided that
     558other tasks are currently more important.  A task that is ready to execute and
     559has a processor assigned is called scheduled.
    529561@item real-time
    593625state by either expiring or being canceled.
    595 @item schedule
    596 The process of choosing which task should
    597 next enter the executing state.
    599627@item schedulable
    600628A set of tasks which can be guaranteed
     632@item schedule
     633The process of choosing which task should
     634next enter the executing state.
     636@item scheduled task
     637A task is @dfn{scheduled} if it is allowed to execute and has a processor
     638assigned.  Such a task executes currently on a processor or is about to start
     639execution.  A task about to start execution it is an heir task on exactly one
     640processor in the system.
     642@item scheduler
     643A @dfn{scheduler} or @dfn{scheduling algorithm} allocates processors to a
     644subset of its set of ready tasks.  So it manages access to the processor
     645resource.  Various algorithms exist to choose the tasks allowed to use a
     646processor out of the set of ready tasks.  One method is to assign each task a
     647priority number and assign the tasks with the lowest priority number to one
     648processor of the set of processors owned by a scheduler instance.
     650@item scheduler instance
     651A @dfn{scheduler instance} is a scheduling algorithm with a corresponding
     652context to store its internal state.  Each processor in the system is owned by
     653at most one scheduler instance.  The processor to scheduler instance assignment
     654is determined at application configuration time.  @xref{Configuring a System
     655Configuring Clustered/Partitioned Schedulers}.
    604657@item segments
    605658Variable sized memory blocks allocated
    631684@item SMCB
    632685An acronym for Semaphore Control Block.
     687@item SMP locks
     688The @dfn{SMP locks} ensure mutual exclusion on the lowest level and are a
     689replacement for the sections of disabled interrupts.  Interrupts are usually
     690disabled while holding an SMP lock.  They are implemented using atomic
     691operations.  Currently a ticket lock is used in RTEMS.
     693@item SMP barriers
     694The @dfn{SMP barriers} ensure that a defined set of independent threads of
     695execution on a set of processors reaches a common synchronization point in
     696time.  They are implemented using atomic operations.  Currently a sense barrier
     697is used in RTEMS.
    634699@item soft real-time system
    671736@item task
    672 A logically complete thread of execution.  The
    673 CPU is allocated among the ready tasks.
     737A logically complete thread of execution.  It consists normally of a set of
     738registers and a stack.  The terms @dfn{task} and @dfn{thread} are synonym in
     739RTEMS.  The scheduler assigns processors to a subset of the ready tasks.
    675741@item Task Control Block
    676742A data structure associated with
    677743each task used by RTEMS to manage that task.
     745@item task migration
     746@dfn{Task migration} happens in case a task stops execution on one processor
     747and resumes execution on another processor.
     749@item task processor affinity
     750The set of processors on which a task is allowed to execute.
    679752@item task switch
    684757@item TCB
    685758An acronym for Task Control Block.
     760@item thread dispatch
     761The @dfn{thread dispatch} transfers control of the processor from the currently
     762executing thread to the heir thread of the processor.
    687764@item tick
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