mirror of https://github.com/rusefi/ChibiOS.git
51 lines
2.6 KiB
Plaintext
51 lines
2.6 KiB
Plaintext
/*
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ChibiOS/RT - Copyright (C) 2006,2007,2008,2009,2010 Giovanni Di Sirio.
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This file is part of ChibiOS/RT.
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ChibiOS/RT is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 3 of the License, or
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(at your option) any later version.
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ChibiOS/RT is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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/**
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* @page article_roundrobin Round Robin scheduling explained
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* Unlike many other RTOSes, ChibiOS/RT supports multiple threads at the
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* same priority level and schedules them using an <i>aggressive</i>
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* round-robin strategy.<br>
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* The strategy is defined as aggressive because any scheduling event
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* causes the round-robin threads to rotate.<br>
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* A round-robin rotation can happen because of the following events:
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* - The currently executed thread voluntarily invokes the @p chThdYield()
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* API in order to allow the execution of another thread at the same
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* priority level, if any.
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* - The currently executed thread voluntarily goes into a sleep state
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* (see @ref thread_states), when the thread is awakened it goes behind
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* any other thread at the same priority level.
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* - The currently executed thread is preempted by an higher priority
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* thread, the thread is reinserted in the ready list (see @ref scheduling)
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* behind any other thread at the same priority level.
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* - If the @p CH_TIME_QUANTUM configuration constant is set to a value
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* greater than zero and if the specified time quantum expired and if
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* a thread with equal priority is ready then the currently executing
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* thread is automatically reinserted in the ready list behind any
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* other thread at the same priority level.
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* .
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* As you can see the @p CH_TIME_QUANTUM setting is really useful only if
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* there are threads at the same priority level that can run not preempted
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* for long periods of time and that do not explicitly yield using
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* @p chThdYield(). Because of this you should consider setting
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* @p CH_TIME_QUANTUM to zero in your configuration file, this makes the
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* kernel much faster and smaller and <b>does not</b> forbid the use of
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* multiple threads at the same priority level.
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*/
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