diff options
| -rw-r--r-- | c-user/symmetric_multiprocessing_services.rst | 22 |
1 files changed, 22 insertions, 0 deletions
diff --git a/c-user/symmetric_multiprocessing_services.rst b/c-user/symmetric_multiprocessing_services.rst index b2773e7..91c1d27 100644 --- a/c-user/symmetric_multiprocessing_services.rst +++ b/c-user/symmetric_multiprocessing_services.rst @@ -809,3 +809,25 @@ RTEMS provides two means for per-processor data: `<rtems/score/percpudata.h> <https://git.rtems.org/rtems/tree/cpukit/include/rtems/score/percpudata.h>`_. This API is not intended for general application use. Please ask on the development mailing list in case you want to use it. + +Thread Pinning +-------------- + +Thread pinning ensures that a thread is only dispatched to the processor on +which it is pinned. It may be used to access per-processor data structures in +critical sections with enabled thread dispatching, e.g. a pinned thread is +allowed to block. The `_Thread_Pin()` operation will pin the executing thread +to its current processor. A thread may be pinned recursively, the last unpin +request via `_Thread_Unpin()` revokes the pinning. + +Thread pinning should be used only for short critical sections and not all +the time. Thread pinning is a very low overhead operation in case the +thread is not preempted during the pinning. A preemption will result in +scheduler operations to ensure that the thread executes only on its pinned +processor. Thread pinning must be used with care, since it prevents help +through the locking protocols. This makes the :ref:`OMIP <OMIP>` and +:ref:`MrsP <MrsP>` locking protocols ineffective if pinned threads are +involved. + +The thread pinning is not intended for general application use. Please ask on +the development mailing list in case you want to use it. |