source: rtems/cpukit/rtems/src/ratemonperiod.c @ 2d2352b

/**
 *  @file
 *
 *  @brief Rate Monotonic Support
 *  @ingroup ClassicRateMon
 */

/*
 *  COPYRIGHT (c) 1989-2010.
 *  On-Line Applications Research Corporation (OAR).
 *
 *  The license and distribution terms for this file may be
 *  found in the file LICENSE in this distribution or at
 *  http://www.rtems.com/license/LICENSE.
 */

#if HAVE_CONFIG_H
#include "config.h"
#endif

#include <rtems/system.h>
#include <rtems/rtems/status.h>
#include <rtems/rtems/support.h>
#include <rtems/score/isr.h>
#include <rtems/score/object.h>
#include <rtems/rtems/ratemon.h>
#include <rtems/score/thread.h>

bool _Rate_monotonic_Get_status(
  Rate_monotonic_Control        *the_period,
  Rate_monotonic_Period_time_t  *wall_since_last_period,
  Thread_CPU_usage_t            *cpu_since_last_period
)
{
  #ifndef __RTEMS_USE_TICKS_FOR_STATISTICS__
    Timestamp_Control        uptime;
  #endif
    Thread_Control          *owning_thread = the_period->owner;
    Thread_CPU_usage_t       used;

  /*
   *  Determine elapsed wall time since period initiated.
   */
  #ifndef __RTEMS_USE_TICKS_FOR_STATISTICS__
    _TOD_Get_uptime( &uptime );
    _Timestamp_Subtract(
      &the_period->time_period_initiated, &uptime, wall_since_last_period
    );
  #else
    *wall_since_last_period =
      _Watchdog_Ticks_since_boot - the_period->time_period_initiated;
  #endif

  /*
   *  Determine cpu usage since period initiated.
   */
  used = owning_thread->cpu_time_used;

  #ifndef __RTEMS_USE_TICKS_FOR_STATISTICS__
    if (owning_thread == _Thread_Executing) {

      Thread_CPU_usage_t ran;

      /* How much time time since last context switch */
      _Timestamp_Subtract(
        &_Thread_Time_of_last_context_switch, &uptime, &ran
      );

      /* cpu usage += ran */
      _Timestamp_Add_to( &used, &ran );

      /*
       *  The cpu usage info was reset while executing.  Can't
       *  determine a status.
       */
      if (_Timestamp_Less_than(&used, &the_period->cpu_usage_period_initiated))
        return false;

       /* used = current cpu usage - cpu usage at start of period */
      _Timestamp_Subtract(
         &the_period->cpu_usage_period_initiated,
         &used,
         cpu_since_last_period
      );
    }
  #else
      /*
       *  The cpu usage info was reset while executing.  Can't
       *  determine a status.
       */
      if (used < the_period->cpu_usage_period_initiated)
        return false;

      *cpu_since_last_period = used - the_period->cpu_usage_period_initiated;
  #endif
  return true;
}

void _Rate_monotonic_Initiate_statistics(
  Rate_monotonic_Control *the_period
)
{
  Thread_Control *owning_thread = the_period->owner;

  /*
   *  If using nanosecond statistics, we need to obtain the uptime.
   */
  #ifndef __RTEMS_USE_TICKS_FOR_STATISTICS__
    Timestamp_Control  uptime;

    _TOD_Get_uptime( &uptime );
  #endif

  /*
   *  Set the starting point and the CPU time used for the statistics.
   */
  #ifndef __RTEMS_USE_TICKS_FOR_STATISTICS__
    the_period->time_period_initiated = uptime;
  #else
    the_period->time_period_initiated = _Watchdog_Ticks_since_boot;
  #endif

  the_period->cpu_usage_period_initiated = owning_thread->cpu_time_used;

  /*
   *  If using nanosecond statistics and the period's thread is currently
   *  executing, then we need to take into account how much time the
   *  executing thread has run since the last context switch.  When this
   *  routine is invoked from rtems_rate_monotonic_period, the owner will
   *  be the executing thread.  When this routine is invoked from
   *  _Rate_monotonic_Timeout, it will not.
   */
  #ifndef __RTEMS_USE_TICKS_FOR_STATISTICS__
    if (owning_thread == _Thread_Executing) {
      Timestamp_Control ran;

      /*
       *  Adjust the CPU time used to account for the time since last
       *  context switch.
       */
      _Timestamp_Subtract(
        &_Thread_Time_of_last_context_switch, &uptime, &ran
      );

      _Timestamp_Add_to( &the_period->cpu_usage_period_initiated, &ran );
    }
  #endif

  _Scheduler_Release_job(the_period->owner, the_period->next_length);
}

static void _Rate_monotonic_Update_statistics(
  Rate_monotonic_Control    *the_period
)
{
  Thread_CPU_usage_t              executed;
  Rate_monotonic_Period_time_t    since_last_period;
  Rate_monotonic_Statistics      *stats;
  bool                            valid_status;

  /*
   *  Assume we are only called in states where it is appropriate
   *  to update the statistics.  This should only be RATE_MONOTONIC_ACTIVE
   *  and RATE_MONOTONIC_EXPIRED.
   */

  /*
   *  Update the counts.
   */
  stats = &the_period->Statistics;
  stats->count++;

  if ( the_period->state == RATE_MONOTONIC_EXPIRED )
    stats->missed_count++;

  /*
   *  Grab status for time statistics.
   */
  valid_status =
    _Rate_monotonic_Get_status( the_period, &since_last_period, &executed );
  if (!valid_status)
    return;

  /*
   *  Update CPU time
   */
  #ifndef __RTEMS_USE_TICKS_FOR_STATISTICS__
    _Timestamp_Add_to( &stats->total_cpu_time, &executed );

    if ( _Timestamp_Less_than( &executed, &stats->min_cpu_time ) )
      stats->min_cpu_time = executed;

    if ( _Timestamp_Greater_than( &executed, &stats->max_cpu_time ) )
      stats->max_cpu_time = executed;
  #else
    stats->total_cpu_time  += executed;

    if ( executed < stats->min_cpu_time )
      stats->min_cpu_time = executed;

    if ( executed > stats->max_cpu_time )
      stats->max_cpu_time = executed;
  #endif

  /*
   *  Update Wall time
   */
  #ifndef __RTEMS_USE_TICKS_FOR_STATISTICS__
    _Timestamp_Add_to( &stats->total_wall_time, &since_last_period );

    if ( _Timestamp_Less_than( &since_last_period, &stats->min_wall_time ) )
      stats->min_wall_time = since_last_period;

    if ( _Timestamp_Greater_than( &since_last_period, &stats->max_wall_time ) )
      stats->max_wall_time = since_last_period;
  #else

    /* Sanity check wall time */
    if ( since_last_period < executed )
      since_last_period = executed;

    stats->total_wall_time += since_last_period;

    if ( since_last_period < stats->min_wall_time )
      stats->min_wall_time = since_last_period;

    if ( since_last_period > stats->max_wall_time )
      stats->max_wall_time = since_last_period;
  #endif
}

rtems_status_code rtems_rate_monotonic_period(
  rtems_id       id,
  rtems_interval length
)
{
  Rate_monotonic_Control              *the_period;
  Objects_Locations                    location;
  rtems_status_code                    return_value;
  rtems_rate_monotonic_period_states   local_state;
  ISR_Level                            level;

  the_period = _Rate_monotonic_Get( id, &location );

  switch ( location ) {
    case OBJECTS_LOCAL:
      if ( !_Thread_Is_executing( the_period->owner ) ) {
        _Objects_Put( &the_period->Object );
        return RTEMS_NOT_OWNER_OF_RESOURCE;
      }

      if ( length == RTEMS_PERIOD_STATUS ) {
        switch ( the_period->state ) {
          case RATE_MONOTONIC_INACTIVE:
            return_value = RTEMS_NOT_DEFINED;
            break;
          case RATE_MONOTONIC_EXPIRED:
          case RATE_MONOTONIC_EXPIRED_WHILE_BLOCKING:
            return_value = RTEMS_TIMEOUT;
            break;
          case RATE_MONOTONIC_ACTIVE:
          default:              /* unreached -- only to remove warnings */
            return_value = RTEMS_SUCCESSFUL;
            break;
        }
        _Objects_Put( &the_period->Object );
        return( return_value );
      }

      _ISR_Disable( level );
      if ( the_period->state == RATE_MONOTONIC_INACTIVE ) {
        _ISR_Enable( level );

        the_period->next_length = length;

        /*
         *  Baseline statistics information for the beginning of a period.
         */
        _Rate_monotonic_Initiate_statistics( the_period );

        the_period->state = RATE_MONOTONIC_ACTIVE;
        _Watchdog_Initialize(
          &the_period->Timer,
          _Rate_monotonic_Timeout,
          id,
          NULL
        );

        _Watchdog_Insert_ticks( &the_period->Timer, length );
        _Objects_Put( &the_period->Object );
        return RTEMS_SUCCESSFUL;
      }

      if ( the_period->state == RATE_MONOTONIC_ACTIVE ) {
        /*
         *  Update statistics from the concluding period.
         */
        _Rate_monotonic_Update_statistics( the_period );

        /*
         *  This tells the _Rate_monotonic_Timeout that this task is
         *  in the process of blocking on the period and that we
         *  may be changing the length of the next period.
         */
        the_period->state = RATE_MONOTONIC_OWNER_IS_BLOCKING;
        the_period->next_length = length;

        _ISR_Enable( level );

        _Thread_Executing->Wait.id = the_period->Object.id;
        _Thread_Set_state( _Thread_Executing, STATES_WAITING_FOR_PERIOD );

        /*
         *  Did the watchdog timer expire while we were actually blocking
         *  on it?
         */
        _ISR_Disable( level );
          local_state = the_period->state;
          the_period->state = RATE_MONOTONIC_ACTIVE;
        _ISR_Enable( level );

        /*
         *  If it did, then we want to unblock ourself and continue as
         *  if nothing happen.  The period was reset in the timeout routine.
         */
        if ( local_state == RATE_MONOTONIC_EXPIRED_WHILE_BLOCKING )
          _Thread_Clear_state( _Thread_Executing, STATES_WAITING_FOR_PERIOD );

        _Objects_Put( &the_period->Object );
        return RTEMS_SUCCESSFUL;
      }

      if ( the_period->state == RATE_MONOTONIC_EXPIRED ) {
        /*
         *  Update statistics from the concluding period
         */
        _Rate_monotonic_Update_statistics( the_period );

        _ISR_Enable( level );

        the_period->state = RATE_MONOTONIC_ACTIVE;
        the_period->next_length = length;

        _Watchdog_Insert_ticks( &the_period->Timer, length );
        _Scheduler_Release_job(the_period->owner, the_period->next_length);
        _Objects_Put( &the_period->Object );
        return RTEMS_TIMEOUT;
      }

      /*
       *  These should never happen so just return invalid Id.
       *    - RATE_MONOTONIC_OWNER_IS_BLOCKING:
       *    - RATE_MONOTONIC_EXPIRED_WHILE_BLOCKING:
       */
#if defined(RTEMS_MULTIPROCESSING)
    case OBJECTS_REMOTE:            /* should never return this */
#endif
    case OBJECTS_ERROR:
      break;
  }

  return RTEMS_INVALID_ID;
}