| 1 | package de.uka.ipd.sdq.scheduler.timeslice.impl; |
| 2 | |
| 3 | import de.uka.ipd.sdq.scheduler.priority.IPriority; |
| 4 | import de.uka.ipd.sdq.scheduler.processes.impl.ProcessWithPriority; |
| 5 | |
| 6 | public class PriorityDependentTimeSlice extends ContinuousTimeSlice { |
| 7 | |
| 8 | private double min_time_to_be_scheduled; // Default value for Linux no x86 systems: 11 |
| 9 | |
| 10 | public PriorityDependentTimeSlice(ProcessWithPriority process, double basic_timeslice, double min_timeslice, double min_time_to_be_scheduled) { |
| 11 | double computed_timeslice = computeTicksFromPriority(process |
| 12 | .getStaticPriority(), basic_timeslice); |
| 13 | this.timeslice = Math.max(computed_timeslice, min_timeslice); |
| 14 | this.min_time_to_be_scheduled = min_time_to_be_scheduled; |
| 15 | } |
| 16 | |
| 17 | /** |
| 18 | * Computes the length of the current time slice according to the Linux |
| 19 | * 2.6.18 Scheduler. |
| 20 | * |
| 21 | * @param process |
| 22 | * @return |
| 23 | */ |
| 24 | public static double computeTicksFromPriority(IPriority prio, double basic_timeslice) { |
| 25 | double basic = getBasicTimeSlice(prio, basic_timeslice); |
| 26 | IPriority max_prio = prio.getManager().getHighestPriority(); |
| 27 | IPriority min_prio = prio.getManager().getLowestPriority(); |
| 28 | int distance = min_prio.distance(prio) + 1; |
| 29 | double factor = (min_prio.distance(max_prio) + 1) / 2.0; |
| 30 | return basic * distance / factor; |
| 31 | } |
| 32 | |
| 33 | /** |
| 34 | * Processes with a static priority above default are preferred. |
| 35 | * |
| 36 | * @param static_prio |
| 37 | * @return |
| 38 | */ |
| 39 | public static double getBasicTimeSlice(IPriority static_prio, double basicTimeslice) { |
| 40 | IPriority default_prio = static_prio.getManager().getDefaultPriority(); |
| 41 | if (static_prio.greaterThan(default_prio)) { |
| 42 | return basicTimeslice * 4; |
| 43 | } else { |
| 44 | return basicTimeslice; |
| 45 | } |
| 46 | } |
| 47 | |
| 48 | @Override |
| 49 | public void updateTimeForScheduling() { |
| 50 | // if the remaining time is smaller than a jiffies the |
| 51 | // timeslice needs to be reset first. |
| 52 | if (remaining_time < min_time_to_be_scheduled){ |
| 53 | remaining_time = 0; |
| 54 | } |
| 55 | } |
| 56 | } |