ardupilot/libraries/AP_Scheduler/AP_Scheduler.cpp

200 lines
6.5 KiB
C++

/*
This program 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.
This program 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/>.
*/
/*
* main loop scheduler for APM
* Author: Andrew Tridgell, January 2013
*
*/
#include "AP_Scheduler.h"
#include <AP_HAL/AP_HAL.h>
#include <AP_Param/AP_Param.h>
#include <AP_Vehicle/AP_Vehicle.h>
#include <stdio.h>
#if APM_BUILD_TYPE(APM_BUILD_ArduCopter)
#define SCHEDULER_DEFAULT_LOOP_RATE 400
#else
#define SCHEDULER_DEFAULT_LOOP_RATE 50
#endif
extern const AP_HAL::HAL& hal;
int8_t AP_Scheduler::current_task = -1;
const AP_Param::GroupInfo AP_Scheduler::var_info[] = {
// @Param: DEBUG
// @DisplayName: Scheduler debug level
// @Description: Set to non-zero to enable scheduler debug messages. When set to show "Slips" the scheduler will display a message whenever a scheduled task is delayed due to too much CPU load. When set to ShowOverruns the scheduled will display a message whenever a task takes longer than the limit promised in the task table.
// @Values: 0:Disabled,2:ShowSlips,3:ShowOverruns
// @User: Advanced
AP_GROUPINFO("DEBUG", 0, AP_Scheduler, _debug, 0),
// @Param: LOOP_RATE
// @DisplayName: Scheduling main loop rate
// @Description: This controls the rate of the main control loop in Hz. This should only be changed by developers. This only takes effect on restart
// @Values: 50:50Hz,100:100Hz,200:200Hz,250:250Hz,300:300Hz,400:400Hz
// @RebootRequired: True
// @User: Advanced
AP_GROUPINFO("LOOP_RATE", 1, AP_Scheduler, _loop_rate_hz, SCHEDULER_DEFAULT_LOOP_RATE),
AP_GROUPEND
};
// constructor
AP_Scheduler::AP_Scheduler(void)
{
_loop_rate_hz.set(SCHEDULER_DEFAULT_LOOP_RATE);
AP_Param::setup_object_defaults(this, var_info);
// only allow 50 to 400 Hz
if (_loop_rate_hz < 50) {
_loop_rate_hz.set(50);
} else if (_loop_rate_hz > 400) {
_loop_rate_hz.set(400);
}
}
// initialise the scheduler
void AP_Scheduler::init(const AP_Scheduler::Task *tasks, uint8_t num_tasks)
{
_tasks = tasks;
_num_tasks = num_tasks;
_last_run = new uint16_t[_num_tasks];
memset(_last_run, 0, sizeof(_last_run[0]) * _num_tasks);
_tick_counter = 0;
}
// one tick has passed
void AP_Scheduler::tick(void)
{
_tick_counter++;
}
/*
run one tick
this will run as many scheduler tasks as we can in the specified time
*/
void AP_Scheduler::run(uint32_t time_available)
{
uint32_t run_started_usec = AP_HAL::micros();
uint32_t now = run_started_usec;
if (_debug > 3 && _perf_counters == nullptr) {
_perf_counters = new AP_HAL::Util::perf_counter_t[_num_tasks];
if (_perf_counters != nullptr) {
for (uint8_t i=0; i<_num_tasks; i++) {
_perf_counters[i] = hal.util->perf_alloc(AP_HAL::Util::PC_ELAPSED, _tasks[i].name);
}
}
}
for (uint8_t i=0; i<_num_tasks; i++) {
uint16_t dt = _tick_counter - _last_run[i];
uint16_t interval_ticks = _loop_rate_hz / _tasks[i].rate_hz;
if (interval_ticks < 1) {
interval_ticks = 1;
}
if (dt >= interval_ticks) {
// this task is due to run. Do we have enough time to run it?
_task_time_allowed = _tasks[i].max_time_micros;
if (dt >= interval_ticks*2) {
// we've slipped a whole run of this task!
if (_debug > 1) {
::printf("Scheduler slip task[%u-%s] (%u/%u/%u)\n",
(unsigned)i,
_tasks[i].name,
(unsigned)dt,
(unsigned)interval_ticks,
(unsigned)_task_time_allowed);
}
}
if (_task_time_allowed <= time_available) {
// run it
_task_time_started = now;
current_task = i;
if (_debug > 3 && _perf_counters && _perf_counters[i]) {
hal.util->perf_begin(_perf_counters[i]);
}
_tasks[i].function();
if (_debug > 3 && _perf_counters && _perf_counters[i]) {
hal.util->perf_end(_perf_counters[i]);
}
current_task = -1;
// record the tick counter when we ran. This drives
// when we next run the event
_last_run[i] = _tick_counter;
// work out how long the event actually took
now = AP_HAL::micros();
uint32_t time_taken = now - _task_time_started;
if (time_taken > _task_time_allowed) {
// the event overran!
if (_debug > 4) {
::printf("Scheduler overrun task[%u-%s] (%u/%u)\n",
(unsigned)i,
_tasks[i].name,
(unsigned)time_taken,
(unsigned)_task_time_allowed);
}
}
if (time_taken >= time_available) {
goto update_spare_ticks;
}
time_available -= time_taken;
}
}
}
// update number of spare microseconds
_spare_micros += time_available;
update_spare_ticks:
_spare_ticks++;
if (_spare_ticks == 32) {
_spare_ticks /= 2;
_spare_micros /= 2;
}
}
/*
return number of micros until the current task reaches its deadline
*/
uint16_t AP_Scheduler::time_available_usec(void)
{
uint32_t dt = AP_HAL::micros() - _task_time_started;
if (dt > _task_time_allowed) {
return 0;
}
return _task_time_allowed - dt;
}
/*
calculate load average as a number from 0 to 1
*/
float AP_Scheduler::load_average(uint32_t tick_time_usec) const
{
if (_spare_ticks == 0) {
return 0.0f;
}
uint32_t used_time = tick_time_usec - (_spare_micros/_spare_ticks);
return used_time / (float)tick_time_usec;
}