CN103810043B - A kind of energy-saving scheduling method being applicable to digital control system periodic duty - Google Patents

Abstract

The present invention discloses a kind of energy-saving scheduling method being applicable to digital control system periodic duty, and its step is as follows: calculate task T in digital control system_iBest execution speed under off-line stateCalculate task T again_iIn best execution speedUnder the execution time, according to earliest-deadline-first principle, task-set is ranked up；When certain task completes, reclaim task T_iFree time Slack_Time, utilize this free time Slack_Time to calculate this task speed of service S under processor specifies continuous voltage；Final speed of service S determining each task forward part according to speed of service S_LSpeed of service S with rear section_H, thus calculate task speed of service S in forward part_LUnder execution time e_x.LWith speed of service S in rear section_HExecution time e_x.H, by required actual execution time e_x.L、e_x.HDispatch execution task；So make the present invention make full use of the free time Slack_Time of system, reduce the speed of service of processor, reach to save the purpose of energy consumption.

Description

A kind of energy-saving scheduling method being applicable to digital control system periodic duty

Technical field

The present invention relates to the Real-Time Scheduling of real-time system field task, a kind of energy-saving scheduling method being applicable to digital control system periodic duty.

Background technology

Real-time system is more and more extensive in the application of fields of numeric control technique and embedded product, seems the most important in the application especially complicated in function, system is huge.This will ask real-time system can provide highly efficient computing capability, and to meet the requirement of radio communication, multimedia application, but high performance cost is exactly high energy consumption.Meanwhile, along with precision, the developing rapidly of footprint day by day of manufacturing process, result in steeply rising of system power dissipation, the high temperature that high power consumption is brought can cause the possibility of system jam to increase, and reduces the reliability of whole system；Accordingly, it is capable to consumption has become the bottleneck of real-time system design.

Dynamic voltage regulation (DVS) technology is a kind of effective low-power consumption and energy optimization technology.Its main thought is for different system loads, on the premise of meeting system real time, reduces operating voltage and the clock frequency of CPU.

Existing low-power consumption scheduling algorithm uses DVS technology, on the premise of meeting system real time, by the free time of recovery system, utilizes free time to reduce working voltage and the clock frequency of processor, to reduce system energy consumption；But it assumes that processor provides continuous print frequency and voltage, and the commercial processor of reality provides only discrete frequency and voltage, in order to ensure task not missed deadlines, its actual motion speed selected is bigger than the ideal velocity calculated in the case of cline frequency, so can cause the waste of system resource.

Summary of the invention

For the weak point of existing low-power consumption scheduling algorithm, the present invention proposes a kind of energy-saving scheduling method being applicable to digital control system periodic duty, and this algorithm can effectively utilize the free time of system, reduces the energy consumption of system.

For realizing above-mentioned algorithm, the present invention uses following technical scheme:

A kind of energy-saving scheduling method being applicable to digital control system periodic duty, it is characterised in that: comprise the steps:

Before task set dispatching, calculate task T in digital control system_iBest execution speed under off-line state

Calculate task T again_iIn best execution speedUnder the execution time, according to earliest-deadline-first principle, task-set is ranked up；

When certain task completes, reclaim this task free time Slack_Time, utilize this free time Slack_Time to calculate speed of service S under processor specifies continuous voltage of this task；

According to speed of service S, determine speed of service S of each task forward part_LSpeed of service S with rear section_H, finally calculate task speed of service S in forward part_LUnder, the execution time e of task_x.LWith speed of service S in rear section_HThe execution time e of task_x.H, finally with required actual execution time e_x.L、e_x.HDispatch execution task.

Earliest-deadline-first principle: deadline is the shortest, priority is the highest, when task T_iDeadline identical time, early arriving of task T_iPriority is high；When task T_iDeadline and arrival time homogeneous while, task T_iWhat serial subscript i was little has higher priority.

Calculate each task T_iBest execution speed under off-line stateIts calculation procedure is as follows:

Utilize execution time C_iWith cycle P_iRatio sum formulaCalculate utilization rate U of system_tot, then by utilization rate U_totMinimum speed S with processor_minComparing, the greater is the best execution speed under off-line state

When certain task completes, reclaiming this task free time Slack_Time, utilize this free time Slack_Time to calculate speed of service S under processor provides continuous voltage of this task, it is as follows that its speed of service S processes step:

Setting up a data structure α queue and record fulfiling ahead of schedule of task, α queue is in off-line state best execution speedUnder ready queue, the arrival time of logger task, deadline and residue perform the time；

Reclaim this task free time Slack_Time, find out fulfiling ahead of schedule in α queue of task, utilize each residue fulfiling task ahead of schedule to perform the time, calculate each free time Slack_Time fulfiling task ahead of schedule, utilize total free time Slack_Time to calculate speed of service S.

According to speed of service S, determine speed of service S of each task forward part_LSpeed of service S with rear section_H, it is as follows that it processes step:

Value according to speed of service S and two adjacent speed S that processor specifies_LowAnd S_HighCompare, when speed of service S is more than S_LowAnd S is less than or equal to S_High(S_Low＜ S≤S_High) time, determine and think speed of service S of task forward part_LIt is speed S that processor specifies_Low, speed of service S of task rear section_HIt is speed S that processor specifies_High。

The invention have the advantages that and advantage:

(1) use the inventive method, owing to making full use of the free time Slack_Time of system, reduce the speed of service of processor, thus save the energy consumption of 30.69% than existing low-power consumption scheduling algorithm.

(2) high temperature brought due to high power consumption can cause the possibility of system jam to increase, and can reduce the reliability of whole system, and the present invention makes full use of the free time Slack_Time of system, reduce system energy consumption, therefore improve the reliability of system.

(3) system encapsulation and the cost of cooling are reduced.Power consumption increase can significantly improve the caloric value of system, and in order to make product normally to dispel the heat, producer inherently increases the investment studied for new encapsulation and cooling technology, and the cost that thus be accordingly used in encapsulation and cooling device can improve.

Accompanying drawing explanation

Fig. 1 is that the inventive method processes flow chart of steps；

Fig. 2 is the simulation experiment result figure of the present invention.

Detailed description of the invention

With embodiment, the present invention program is described in further detail below in conjunction with the accompanying drawings.

See accompanying drawing 1, Fig. 2, be a kind of energy-saving scheduling method being applicable to digital control system periodic duty, it is characterised in that: comprise the steps:

Before task set dispatching, calculate task T in digital control system_iBest execution speed under off-line state

Calculate task T again_iIn best execution speedUnder the execution time, according to earliest-deadline-first principle, task-set is ranked up；

When certain task completes, reclaim this task free time Slack_Time, utilize this free time to calculate speed of service S under processor provides continuous voltage of this task；

According to speed of service S, determine speed of service S of each task forward part_LSpeed of service S with rear section_H, finally calculate task speed of service S in forward part_LUnder execution time e_x.LWith speed of service S in rear section_HUnder execution time e_x.H, finally with required actual execution time e_x.L、e_x.HDispatch execution task.

The inventive method is further illustrated:

Calculate task T_iBest execution speed in off-line state task

Utilization rate U of system is calculated by formula (1)_tot

$U_{\mathrm{tot}}=\underset{i=1}{\overset{n}{\mathrm{\Σ}}}\frac{C_i}{P_i}---\left(1\right)$

In formula, C_i、P_i, i be respectively periodic duty T_iExecution time, cycle, the identifier of task under worst case；N is the number of task.

Task T is calculated by formula (2)_iBest execution speed in off-line state task

$S=\max \{S_{\min },U_{\mathrm{tot}}\}---\left(2\right)$

Wherein S_minIt it is the minimum speed that specifies of processor.

When there being new task to arrive, according to earliest-deadline-first principle, new task is inserted in the relevant position in α queue.

Earliest-deadline-first principle: deadline is the shortest, priority is the highest, when task T_iDeadline identical time, early arriving of task T_iPriority is high；When task T_iDeadline and arrival time homogeneous while, task T_iWhat serial subscript i was little has higher priority.

When certain task completes, reclaiming the Slack_Time time this task free time, utilize this free time Slack_Time to calculate speed of service S under processor provides continuous voltage of this task, it is as follows that its speed of service S processes step:

Setting up a data structure α queue and record fulfiling ahead of schedule of task, α queue is in off-line state best execution speedUnder ready queue, the arrival time of logger task, deadline and residue perform the time；

Reclaim this task free time Slack_Time, find out fulfiling ahead of schedule in α queue of task, utilize each residue fulfiling task ahead of schedule to perform the time, calculate each free time Slack_Time fulfiling task ahead of schedule, utilize total free time Slack_Time to calculate speed of service S.

Each free time Slack_Time fulfiling task ahead of schedule is calculated by formula (3):

$\mathrm{Slack}\_\mathrm{Time}={\mathrm{\Σ}}_{i|d_i\≤d_x}{\mathrm{rem}}_i\left(t\right)-w_x^{S_x}\left(t\right)---\left(3\right)$

In formula, i is the identifier of task, d_i、d_xTask T of being respectively_i、T_xDeadline；rem_iT () is task T_iResidue at moment t performs the time, and the residue execution time of task gradually decreases along with the execution of task；When task completes, the remaining time of task is 0.For task T_xAt moment t with speed S_xResidue under the worst case run performs the time. be can be seen that free time Slack_Time is that the summation of the residue execution time by fulfiling task ahead of schedule calculates with the difference of the residue execution time under worst case by formula (3).

Free time Slack_Time is utilized to calculate speed of service S of task:

Speed of service S of task is calculated by formula (4)

$S=\frac{w_x^{S_x}\left(t\right)}{{\mathrm{rem}}_x\left(t\right)+\mathrm{Slack}\_\mathrm{Time}}---\left(4\right)$

In formula, rem_xT () is task T_xResidue at moment t performs the time, and Slack_Time is the free time of task.When minimum speed S that speed of service S of task specifies than processor_minValue hour, minimum speed S that speed of service S specifies equal to processor_min。

According to speed of service S, determine speed of service S of each task forward part_LSpeed of service S with rear section_H, finally calculate task speed of service S in forward part_LUnder execution time e_x.LWith speed of service S in rear section_HExecution time e_x.H, it is as follows that it processes step:

Value according to speed of service S and two adjacent speed S that processor specifies_LowAnd S_HighCompare, when speed of service S is more than S_LowAnd S is less than or equal to S_High(S_Low＜ S≤S_High) time, determine and think speed of service S of task forward part_LIt is speed S that processor specifies_Low, speed of service S of task rear section_HIt is speed S that processor specifies_High。

Speed of service S in forward part_LUnder, task T_xThe execution time be execution time e_x.L；Speed of service S in rear section_HUnder, task T_xThe execution time be execution time e_x.H。

Task T_xThe execution time meet (5) formula:

e_x=e_x.L+e_x.H(5)

Task T_xExecution time when just arriving to meets (6) formula:

S·e_x=S_L·e_x.L+S_H·e_x.H(6)

Execution time e is learnt by formula (5)_x, by execution time e_xSubstitute into formula (6) and calculate speed of service S in forward part_LUnder, task T_xExecution time e_x.L:

$e_{x.L}=e_x\·\frac{S_H-S}{S_H-S_L}---\left(7\right)$

Execution time e is learnt by formula (7)_x.L, by execution time e_x.LSubstitute into formula (5) and calculate the S of the speed of service in rear section_HUnder, task T_xExecution time e_x.H, finally with required actual execution time e_x.L、e_x.HDispatch execution task.

Claims (5)

1. the energy-saving scheduling method being applicable to digital control system periodic duty, it is characterised in that: include as Lower step:

Before task set dispatching, calculate task T in digital control system_iOptimum operation speed under off-line state Degree

Calculate task T again_iIn best execution speedUnder the execution time, according to earliest-deadline-first Task-set is ranked up by principle；

When certain task completes, reclaim this task free time Slack_Time, utilize this free time Slack_Time calculates this task speed of service S under processor provides continuous voltage；

According to speed of service S, determine speed of service S of each task forward part_LOperation with rear section Speed S_H；Calculate task speed of service S in forward part_LUnder actual execution time e_x.LWith rear Speed of service S of part_HExecution time e_x.H, finally with required actual execution time e_x.L、e_x.HCome Scheduling execution task.

2. according to a kind of energy-saving distribution side being applicable to digital control system periodic duty described in claim 1 Method, it is characterised in that: earliest-deadline-first principle: deadline is the shortest, priority is the highest, when Task T_iDeadline identical time, early arriving of task T_iPriority is high；When task T_iDeadline The while of homogeneous with arrival time, task T_iWhat serial subscript i was little has higher priority.

3. according to a kind of energy-saving distribution side being applicable to digital control system periodic duty described in claim 1 Method, it is characterised in that: calculate each task T_iBest execution speed under off-line stateIt calculates step Rapid as follows:

Utilize execution time C_iWith cycle P_iRatio sum formulaCalculate the utilization rate of system U_tot, then by utilization rate U_totMinimum speed S with processor_minComparing, the greater is under off-line state Best execution speed

4. according to a kind of energy-saving distribution side being applicable to digital control system periodic duty described in claim 1 Method, it is characterised in that: when certain task completes, reclaim the Slack_Time time this task free time, profit The speed of the operation under processor provides continuous voltage of this task is calculated with this free time Slack_Time Degree S, it is as follows that its speed of service S processes step:

Setting up a data structure α queue and record fulfiling ahead of schedule of task, α queue is in off-line state Ready queue under best execution speed, when the arrival time of logger task, deadline and residue perform Between；

Reclaim this task free time Slack_Time, find out fulfiling ahead of schedule in α queue of task, utilize Each residue fulfiling task ahead of schedule performs the time, calculates each free time fulfiling task ahead of schedule Slack_Time, utilizes total free time Slack_Time to calculate speed of service S.

5. according to a kind of energy-saving distribution being applicable to digital control system periodic duty described in claim 1 or 4 Method, it is characterised in that: according to speed of service S, determine speed of service S of each task forward part_LWith Speed of service S of rear section_H, it is as follows that it processes step:

Value according to speed of service S and two adjacent speed S that processor specifies_LowAnd S_HighCompare, When speed of service S is more than S_LowAnd S is less than or equal to S_HighTime, determine and think that the operation of task forward part is fast Degree S_LIt is speed S that processor specifies_Low, speed of service S of task rear section_HIt is processor regulation Speed S_High。