/*
    ChibiOS/RT - Copyright (C) 2006,2007,2008,2009,2010 Giovanni Di Sirio.

    This file is part of ChibiOS/RT.

    ChibiOS/RT is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation; either version 3 of the License, or
    (at your option) any later version.

    ChibiOS/RT is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this program.  If not, see <http://www.gnu.org/licenses/>.
*/

/**
 * @page article_roundrobin Round Robin scheduling explained
 * Unlike many other RTOSes, ChibiOS/RT supports multiple threads at the
 * same priority level and schedules them using an <i>aggressive</i>
 * round-robin strategy.<br>
 * The strategy is defined as aggressive because any scheduling event
 * can cause the round-robin threads to rotate.<br>
 * A round-robin rotation can happen because of the following events:
 * - The currently executed thread voluntarily invokes the @p chThdYield()
 *   API in order to allow the execution of another thread at the same
 *   priority level, if any.
 * - The currently executed thread voluntarily goes into a sleep state
 *   (see @ref thread_states), when the thread is waken it goes behind
 *   all the other threads at the same priority level.
 * - The currently executed thread is preempted by an higher priority
 *   thread, the thread is reinserted in the ready list (see @ref scheduling)
 *   behind all the other threads at the same priority level.
 * - If the @p CH_TIME_QUANTUM configuration constant is set to a value
 *   greater than zero and if the specified time quantum expired and if
 *   a thread with equal priority is ready then the currently executing
 *   thread is automatically reinserted in the ready list behind all the
 *   other threads at the same priority level.
 * .
 * As you can see the @p CH_TIME_QUANTUM setting is really useful only if
 * there are threads at the same priority level that can run not preempted
 * for long periods of time and that do not explicitly yield using
 * @p chThdYield(). Because of this you should consider to set
 * @p CH_TIME_QUANTUM to zero in your configuration file, this makes the
 * kernel much faster and smaller and <b>does not</b> forbid the use of
 * multiple threads at the same priority level.
 */