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#include <algorithm>
#include <set>
#include <stdlib.h>
#include <limits.h>
#include "tasks.h"
#include "math-helper.h"
#include "stl-helper.h"
#include "schedulability.h"
#include "edf/qpa.h"
QPATest::QPATest(unsigned int num_processors)
{
if (num_processors != 1)
{
// This is a uniprocessor test---complain even in non-debug
// builds.
abort();
}
}
static integral_t edf_busy_interval(const TaskSet &ts)
{
integral_t interval = 0;
integral_t total_cost = 0;
// initial guess: sum of all costs.
for (unsigned int i = 0; i < ts.get_task_count(); i++)
interval += ts[i].get_wcet();
total_cost = interval;
do {
interval = total_cost;
total_cost = 0;
for (unsigned int i = 0; i < ts.get_task_count(); i++)
{
integral_t jobs;
jobs = divide_with_ceil(interval, ts[i].get_period());
total_cost += jobs * ts[i].get_wcet();
}
} while (interval != total_cost);
return interval;
}
static integral_t zhang_burns_interval(const TaskSet &ts)
{
integral_t interval = 0;
fractional_t total_scaled_delta = 0;
fractional_t total_util;
ts.get_utilization(total_util);
for (unsigned int i = 0; i < ts.get_task_count(); i++)
{
integral_t dl = ts[i].get_deadline();
integral_t per = ts[i].get_period();
integral_t delta = dl - per;
interval = std::max(interval, delta);
fractional_t util;
ts[i].get_utilization(util);
total_scaled_delta += (per - dl) * util;
}
total_scaled_delta /= (1 - total_util);
interval = std::max(interval, round_up(total_scaled_delta));
return interval;
}
std::set<unsigned long> get_testpoints(const TaskSet &ts,
const integral_t &max_time)
{
std::set<unsigned long> points;
// determine all test points
for (unsigned int i = 0; i < ts.get_task_count(); i++)
{
unsigned long time = ts[i].get_deadline();
for (unsigned long j = 0; time < max_time; j++)
{
points.insert(time);
time += ts[i].get_period();
}
}
return points;
}
static integral_t max_deadline(const Task &task,
const integral_t &max_time)
{
integral_t dl = max_time - task.get_deadline();
// implicit floor in integer division
dl /= task.get_period();
return dl * task.get_period() + task.get_deadline();
}
static unsigned long min_relative_deadline(const TaskSet &ts)
{
unsigned long dl = ULONG_MAX;
for (unsigned int i = 0; i < ts.get_task_count(); i++)
dl = std::min(dl, ts[i].get_deadline());
return dl;
}
static integral_t get_largest_testpoint(const TaskSet &ts,
const integral_t &max_time)
{
integral_t point = 0;
for (unsigned int i = 0; i < ts.get_task_count(); i++)
{
unsigned long dl = ts[i].get_deadline();
if (dl < max_time)
{
integral_t max_dl = max_deadline(ts[i], max_time);
if (max_dl == max_time)
max_dl -= ts[i].get_period();
if (max_dl > point)
point = max_dl;
}
}
return point;
}
bool QPATest::is_schedulable(const TaskSet &ts, bool check_preconditions)
{
fractional_t util;
ts.get_utilization(util);
if (util > 1)
return false;
integral_t max_interval = edf_busy_interval(ts);
unsigned long min_interval = min_relative_deadline(ts);
if (util < 1)
max_interval = std::min(max_interval, zhang_burns_interval(ts));
integral_t next = get_largest_testpoint(ts, max_interval);
integral_t demand;
integral_t interval;
do {
interval = next;
ts.bound_demand(interval, demand);
if (demand < interval)
next = demand;
else
next = get_largest_testpoint(ts, interval);
} while (demand <= interval && demand > min_interval);
return demand <= min_interval;
}
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