134 lines
4.2 KiB
C
134 lines
4.2 KiB
C
/****************************************************************************
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* sched/sched/sched_rrgetinterval.c
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*
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* Copyright (C) 2007, 2009 Gregory Nutt. All rights reserved.
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* Author: Gregory Nutt <gnutt@nuttx.org>
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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*
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in
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* the documentation and/or other materials provided with the
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* distribution.
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* 3. Neither the name NuttX nor the names of its contributors may be
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* used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
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* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
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* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
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* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
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* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
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* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
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* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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*
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****************************************************************************/
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/****************************************************************************
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* Included Files
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****************************************************************************/
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#include <nuttx/config.h>
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#include <sys/types.h>
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#include <sched.h>
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#include <errno.h>
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#include <nuttx/arch.h>
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#include "sched/sched.h"
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#include "clock/clock.h"
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/****************************************************************************
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* Public Functions
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****************************************************************************/
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/****************************************************************************
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* Name: sched_rr_get_interval
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*
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* Description:
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* sched_rr_get_interval() writes the timeslice interval for task
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* identified by 'pid' into the timespec structure pointed to by
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* 'interval.' If pid is zero, the timeslice for the calling process
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* is written into 'interval. The identified process should be running
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* under the SCHED_RRscheduling policy.'
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*
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* Inputs:
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* pid - the task ID of the task. If pid is zero, the priority of the
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* calling task is returned.
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* interval - a structure used to return the time slice
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*
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* Return Value:
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* On success, sched_rr_get_interval() returns OK (0). On error,
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* ERROR (-1) is returned, and errno is set to:
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*
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* EFAULT -- Cannot copy to interval
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* EINVAL Invalid pid.
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* ENOSYS The system call is not yet implemented.
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* ESRCH The process whose ID is pid could not be found.
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*
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* Assumptions:
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*
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****************************************************************************/
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int sched_rr_get_interval(pid_t pid, struct timespec *interval)
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{
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#if CONFIG_RR_INTERVAL > 0
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FAR struct tcb_s *rrtcb;
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/* If pid is zero, the timeslice for the calling process is written
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* into 'interval.'
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*/
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if (!pid)
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{
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rrtcb = this_task();
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}
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/* Return a special error code on invalid PID */
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else if (pid < 0)
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{
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set_errno(EINVAL);
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return ERROR;
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}
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/* Otherwise, lookup the TCB associated with this PID */
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else
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{
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rrtcb = sched_gettcb(pid);
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if (!rrtcb)
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{
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set_errno(ESRCH);
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return ERROR;
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}
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}
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if (!interval)
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{
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set_errno(EFAULT);
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return ERROR;
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}
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/* Convert the timeslice value from ticks to timespec */
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interval->tv_sec = CONFIG_RR_INTERVAL / MSEC_PER_SEC;
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interval->tv_nsec = (CONFIG_RR_INTERVAL % MSEC_PER_SEC) * NSEC_PER_MSEC;
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return OK;
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#else
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set_errno(ENOSYS);
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return ERROR;
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#endif
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}
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