| .. _microkernel_fibers: |
| |
| Fiber Services |
| ############## |
| |
| Concepts |
| ******** |
| |
| A fiber is a lightweight, non-preemptible thread of execution that implements |
| a portion of an application's processing. It is is normally used when writing |
| device drivers and other performance critical work. |
| |
| A microkernel application can use all of the fiber capabilities that are |
| available to a nanokernel application; for more information see |
| :ref:`Nanokernel Fiber Services <nanokernel_fibers>`. |
| |
| While a fiber often uses one or more nanokernel object types to carry |
| out its work, it can also interact with microkernel events and semaphores |
| to a limited degree. For example, a fiber can signal a task by giving a |
| microkernel semaphore, but it cannot take a microkernel semaphore. For more |
| information see :ref:`microkernel_events` and :ref:`microkernel_semaphores`. |
| |
| |
| .. _microkernel_server_fiber: |
| |
| Microkernel Server Fiber |
| ======================== |
| |
| The microkernel automatically spawns a system thread, known as the |
| *microkernel server* fiber, which performs most operations involving |
| microkernel objects; see :ref:`Microkernel Server <microkernel_server>`. |
| |
| Both the fiber's stack size and scheduling priority can be configured, |
| using the :option:`MICROKERNEL_SERVER_STACK_SIZE` and |
| :option:`MICROKERNEL_SERVER_PRIORITY` configuration options, respectively. |
| |
| By default, the microkernel server has priority 0 (i.e. highest priority). |
| However, this can be changed so that the nanokernel scheduler gives precedence |
| to other fibers, such as time-sensitive device driver or application fibers. |