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nuttx/sched/sched/sched_setscheduler.c

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/****************************************************************************
* sched/sched/sched_setscheduler.c
*
* Copyright (C) 2007, 2009, 2012, 2015-2016 Gregory Nutt. All rights reserved.
* Author: Gregory Nutt <gnutt@nuttx.org>
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
* 3. Neither the name NuttX nor the names of its contributors may be
* used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*
****************************************************************************/
/****************************************************************************
* Included Files
****************************************************************************/
#include <nuttx/config.h>
#include <sys/types.h>
#include <unistd.h>
#include <sched.h>
#include <assert.h>
#include <errno.h>
#include <nuttx/irq.h>
#include <nuttx/arch.h>
#include "sched/sched.h"
#include "clock/clock.h"
/****************************************************************************
* Public Functions
****************************************************************************/
/****************************************************************************
* Name:sched_setscheduler
*
* Description:
* sched_setscheduler() sets both the scheduling policy and the priority
* for the task identified by pid. If pid equals zero, the scheduler of
* the calling task will be set. The parameter 'param' holds the priority
* of the thread under the new policy.
*
* Inputs:
* pid - the task ID of the task to modify. If pid is zero, the calling
* task is modified.
* policy - Scheduling policy requested (either SCHED_FIFO or SCHED_RR)
* param - A structure whose member sched_priority is the new priority.
* The range of valid priority numbers is from SCHED_PRIORITY_MIN
* through SCHED_PRIORITY_MAX.
*
* Return Value:
* On success, sched_setscheduler() returns OK (zero). On error, ERROR
* (-1) is returned, and errno is set appropriately:
*
* EINVAL The scheduling policy is not one of the recognized policies.
* ESRCH The task whose ID is pid could not be found.
*
* Assumptions:
*
****************************************************************************/
int sched_setscheduler(pid_t pid, int policy,
FAR const struct sched_param *param)
{
FAR struct tcb_s *tcb;
irqstate_t flags;
#ifdef CONFIG_SCHED_SPORADIC
int errcode;
#endif
int ret;
/* Check for supported scheduling policy */
if (policy != SCHED_FIFO
#if CONFIG_RR_INTERVAL > 0
&& policy != SCHED_RR
#endif
#ifdef CONFIG_SCHED_SPORADIC
&& policy != SCHED_SPORADIC
#endif
)
{
set_errno(EINVAL);
return ERROR;
}
/* Check if the task to modify the calling task */
if (pid == 0)
{
pid = getpid();
}
/* Verify that the pid corresponds to a real task */
tcb = sched_gettcb(pid);
if (!tcb)
{
set_errno(ESRCH);
return ERROR;
}
/* Prohibit any context switches while we muck with priority and scheduler
* settings.
*/
sched_lock();
/* Further, disable timer interrupts while we set up scheduling policy. */
flags = enter_critical_section();
tcb->flags &= ~TCB_FLAG_POLICY_MASK;
switch (policy)
{
default:
DEBUGPANIC();
case SCHED_FIFO:
{
#ifdef CONFIG_SCHED_SPORADIC
/* Cancel any on-going sporadic scheduling */
if ((tcb->flags & TCB_FLAG_POLICY_MASK) == TCB_FLAG_SCHED_SPORADIC)
{
DEBUGVERIFY(sched_sporadic_stop(tcb));
}
#endif
/* Save the FIFO scheduling parameters */
tcb->flags |= TCB_FLAG_SCHED_FIFO;
#if CONFIG_RR_INTERVAL > 0 || defined(CONFIG_SCHED_SPORADIC)
tcb->timeslice = 0;
#endif
}
break;
#if CONFIG_RR_INTERVAL > 0
case SCHED_RR:
{
#ifdef CONFIG_SCHED_SPORADIC
/* Cancel any on-going sporadic scheduling */
if ((tcb->flags & TCB_FLAG_POLICY_MASK) == TCB_FLAG_SCHED_SPORADIC)
{
DEBUGVERIFY(sched_sporadic_stop(tcb));
}
#endif
/* Save the round robin scheduling parameters */
tcb->flags |= TCB_FLAG_SCHED_RR;
tcb->timeslice = MSEC2TICK(CONFIG_RR_INTERVAL);
}
break;
#endif
#ifdef CONFIG_SCHED_SPORADIC
case SCHED_SPORADIC:
{
FAR struct sporadic_s *sporadic;
int repl_ticks;
int budget_ticks;
if (param->sched_ss_max_repl < 1 ||
param->sched_ss_max_repl > CONFIG_SCHED_SPORADIC_MAXREPL)
{
errcode = EINVAL;
goto errout_with_irq;
}
/* Convert timespec values to system clock ticks */
(void)clock_time2ticks(&param->sched_ss_repl_period, &repl_ticks);
(void)clock_time2ticks(&param->sched_ss_init_budget, &budget_ticks);
/* Avoid zero/negative times */
if (repl_ticks < 1)
{
repl_ticks = 1;
}
if (budget_ticks < 1)
{
budget_ticks = 1;
}
/* The replenishment period must be greater than or equal to the
* budget period.
*/
#if 1
/* REVISIT: In the current implementation, the budget cannot
* exceed half the duty.
*/
if (repl_ticks < (2 * budget_ticks))
#else
if (repl_ticks < budget_ticks)
#endif
{
errcode = EINVAL;
goto errout_with_irq;
}
/* Initialize/reset current sporadic scheduling */
if ((tcb->flags & TCB_FLAG_POLICY_MASK) == TCB_FLAG_SCHED_SPORADIC)
{
ret = sched_sporadic_reset(tcb);
}
else
{
ret = sched_sporadic_initialize(tcb);
}
/* Save the sporadic scheduling parameters. */
if (ret >= 0)
{
tcb->flags |= TCB_FLAG_SCHED_SPORADIC;
tcb->timeslice = budget_ticks;
sporadic = tcb->sporadic;
DEBUGASSERT(sporadic != NULL);
sporadic->hi_priority = param->sched_priority;
sporadic->low_priority = param->sched_ss_low_priority;
sporadic->max_repl = param->sched_ss_max_repl;
sporadic->repl_period = repl_ticks;
sporadic->budget = budget_ticks;
/* And restart at the next replenishment interval */
ret = sched_sporadic_start(tcb);
}
/* Handle errors */
if (ret < 0)
{
errcode = -ret;
goto errout_with_irq;
}
}
break;
#endif
#if 0 /* Not supported */
case SCHED_OTHER:
tcb->flags |= TCB_FLAG_SCHED_OTHER;
break;
#endif
}
leave_critical_section(flags);
/* Set the new priority */
ret = sched_reprioritize(tcb, param->sched_priority);
sched_unlock();
return (ret >= 0) ? OK : ERROR;
#ifdef CONFIG_SCHED_SPORADIC
errout_with_irq:
set_errno(errcode);
leave_critical_section(flags);
sched_unlock();
return ERROR;
#endif
}
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