CN106878132B

CN106878132B - Bus scheduling method based on period and priority

Info

Publication number: CN106878132B
Application number: CN201710083541.9A
Authority: CN
Inventors: 刘靖; 郑云龙; 冷佳鹏
Original assignee: Beijing Catic General Technology Co Ltd
Current assignee: Beijing Catic General Technology Co Ltd
Priority date: 2017-02-16
Filing date: 2017-02-16
Publication date: 2020-01-07
Anticipated expiration: 2037-02-16
Also published as: CN106878132A

Abstract

The invention discloses a bus network scheduling method based on period and priority, which comprises the following steps: dividing a bus network scheduling period into a determined scheduling section and a competition scheduling section, wherein the determined scheduling section is used for transmitting small data blocks with a specific period, and the competition scheduling section is used for transmitting large data blocks with the specific period; the non-periodic messages are divided into high-priority non-periodic messages and low-priority non-periodic messages according to priorities, the high-priority non-periodic messages can be inserted into the whole bus network scheduling period at any time, and the current executing periodic messages or the low-priority non-periodic messages are interrupted; for low priority aperiodic messages, they can only be inserted in the contention scheduling segment. The invention can give consideration to the data scheduling of various modules contained in the bus network with different rates and priorities, reduces the network scheduling delay and improves the utilization rate of the bus network bandwidth.

Description

Bus scheduling method based on period and priority

Technical Field

The invention relates to the technical field of network communication and high-speed buses, in particular to a bus scheduling method based on cycles and priorities.

Background

The high-speed data bus technology is a key technology of an avionics system, the avionics system is a brain and a neural center of a modern airplane, an airborne bus network is a key neural network of the modern airplane, airborne network transmission is triggered based on time and events, but the traditional bus technology does not give consideration to processing between the time and the events so as to achieve a balanced state, for example, an MIL-STD-1553 bus is carried out in a complete time slice mode for bus scheduling, and an FC bus is based on event scheduling.

The airborne bus network is a complex network, the bus comprises modules with various rates, the data volume of each module is different, the data blocks have priorities, and the traditional scheduling mode cannot give consideration to the processing aspects in the aspects.

The network scheduling delay is the key of the airborne network, the scheduling delay directly affects the utilization rate of network bandwidth, when the scheduling average delay is too large, the network data throughput cannot be met, and the requirements have to be met by increasing the bandwidth and other cost improving modes. Therefore, how to consider time and events, reduce network scheduling delay and improve the utilization rate of the bus bandwidth is the technical problem to be solved by the invention.

Disclosure of Invention

In view of the above-mentioned deficiencies of the prior art, the present invention provides a bus scheduling method based on cycles and priorities.

According to an aspect of the present invention, there is provided a bus scheduling method based on cycles and priorities, the method including: the bus is scheduled according to periods, each scheduling period is divided into a determined scheduling section and a competitive scheduling section, and for messages to be scheduled with high priority, the messages to be scheduled can be scheduled at any time in the determined scheduling section and the competitive scheduling section, and other messages with low priority which are currently executed are interrupted; for messages to be scheduled with low priority, they can be scheduled only in the contention scheduling segment.

According to another aspect of the present invention, the certain scheduling segment is used for transmitting a small data block having a specific period, and the contention scheduling segment is used for transmitting a large data block having a specific period.

According to another aspect of the invention, the transmission priority of the low-priority aperiodic message is higher than that of the periodic message in the contention scheduling segment and lower than that of the high-priority aperiodic message.

According to another aspect of the invention, the bus cycles are timed by the network controller, a cycle start packet is sent at the arrival of each new cycle, and the scheduled segments are determined to be at the start of each cycle. The network controller broadcasts the remaining time of the current network cycle through the network synchronization packet, each network node reloads the cycle time down counter after receiving the network synchronization packet, and waits for the next cycle to start transmission when the time value of the down counter is not enough to send a non-periodic message.

According to another aspect of the invention, small blocks of data having a particular period are transmitted in a time-triggered manner in certain scheduled segments, with a fixed transmission once per bus cycle. Large data blocks with a specific period are transmitted in a contention scheduling section in an event-triggered manner, a plurality of possible large data blocks are polled in each bus network period, if any, the data is transmitted until the bus network period is finished, and if the data blocks are large, the polling can be continued in the next period and the data can be transmitted through a plurality of continuous bus periods.

Compared with the prior art, the invention can give consideration to the data scheduling of various modules contained in the bus network with different rates and priorities, reduce the network scheduling delay and improve the utilization rate of the bus network bandwidth.

Drawings

FIG. 1 is a schematic diagram of a bus network scheduling cycle according to the present invention.

Detailed Description

The present invention is described in further detail below with reference to the attached drawing figures.

The invention designs a new scheduling mode aiming at the existing network triggering conditions, considers the characteristics of data transmitted on a bus, such as complex length, periodicity, burstiness, priority and the like, and designs an effective method for reducing scheduling delay and improving bus efficiency.

Network scheduling requires a node as a network controller, and the network controller realizes network cycle control, network cycle packet broadcasting, cycle message network scheduling and network head segment instruction list functions.

The scheduling is implemented by a periodic method, as shown in fig. 1, the bus scheduling period message is divided into the following two parts according to the size of the data block:

1. determining a scheduling segment

The scheduling segment is determined to be the determined scheduling segment time in one period, the scheduling segment is determined to be located at the starting position of each period, and the period interval has certainty, so that the scheduling segment execution period message is determined to have good period characteristics and is suitable for transmitting small data blocks with a specific period.

2. Contention scheduling segment

The contention scheduling section is a contention scheduling section time in one period, is suitable for transmitting a large data block having a specific period, and may schedule one period to transmit a plurality of messages or a plurality of periods to transmit one message according to the size and the periodic characteristics of the data block.

The bus scheduling non-periodic message is also divided into two stages according to the priority, and the two stages are respectively as follows:

1. high priority transmission zone

The high-priority transmission area is used for transmitting high-priority aperiodic messages, the aperiodic messages are emergencies in the network, and the emergencies are divided into two priorities, namely high priority and low priority. High priority means that the network device is required to respond as quickly as possible, so that a high priority message can be inserted at any time throughout a bus cycle, interrupting a currently executing periodic message or a low priority aperiodic message.

Network interrupts are similar to software and hardware interrupts, message vectors in computers, and belong to high priority aperiodic messages in a cycle. The nodes in the network can initiate network interruption, and after receiving the network interruption, the network controller triggers network interruption scheduling according to the network interruption vector, wherein the scheduling mode has the highest priority and is suitable for the emergency of the nodes in the network. The data blocks of the network interrupt data frame are small, so that the maximum real-time performance can be achieved.

2 low priority transmission area

The low priority transmission area is used for transmitting low priority non-periodic messages, the time of the low priority execution area is coincident with the time of the competitive scheduling section, but the transmission priority of the low priority non-periodic messages is greater than the periodic messages in the competitive scheduling and less than the high priority non-periodic messages.

The network synchronization packet is the starting point of the scheduling mode of the invention, the network controller times the network period and sends a period starting packet when each new period arrives; and after the scheduling section is determined to be completed, sending a network low-priority initial packet until a new period starts to send a period initial packet, and simultaneously broadcasting the remaining time of the current network period by a network synchronization packet.

And (3) network period synchronization, wherein each network node reloads a period time down counter after receiving a network synchronization packet, and when the time value of the down counter is less than the time value of a sent non-periodic message, the next period is required to be waited for starting transmission.

Periodic small data block transmission

The periodic data of the small data blocks with low bandwidth is executed in a time-triggered mode in a determined scheduling section, and is fixedly transmitted once in each bus period. Although each cycle needs to be transmitted, the data volume is not large, the occupied bandwidth is small, and the data can be scheduled only once every several bus cycles according to the cycle characteristics of the data block, so that the occupied bandwidth is further reduced.

Periodic large data block transmission

And executing the large data block high-bandwidth periodic data in a competitive scheduling section in an event triggering mode. Polling is performed for a number of possible large data blocks in each bus network cycle, and if there is data, a certain amount of data is transmitted until the end of the bus network cycle. If the data block is large, polling may continue in the next cycle, with transmissions occurring over several consecutive bus cycles.

Aperiodic high priority data block transmission

The non-periodic high-priority data block is transmitted in a high-priority transmission area, a network node can initiate a high-priority non-periodic message at any time, and the non-periodic high-priority data block has high priority and is used for the node to actively initiate the transmission of the small data block emergency message.

Aperiodic low priority data block transmission

The non-periodic low-priority big data is transmitted in the low-priority transmission area, the network node can initiate the non-periodic low-priority data after receiving the network low-priority synchronous packet, and the deterministic periodic transmission is completed, so the non-periodic low-priority data can initiate any large amount of data transmission under the condition that the bandwidth of the exchange interconnection equipment is enough until the network period starting packet is received.

As will be appreciated by one skilled in the art, embodiments of the present invention may be provided as a method, system, or computer program product. Accordingly, the present invention may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, the present invention may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, optical storage, and the like) having computer-usable program code embodied therein.

The present invention is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each flow and/or block of the flow diagrams and/or block diagrams, and combinations of flows and/or blocks in the flow diagrams and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.

These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart flow or flows and/or block diagram block or blocks.

These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks. It will be apparent to those skilled in the art that various changes and modifications may be made in the present invention without departing from the spirit and scope of the invention. Thus, if such modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include such modifications and variations.

Claims

1. A bus scheduling method based on cycle and priority is characterized in that scheduling is controlled by a network controller on a bus, and the network controller realizes network cycle control, network cycle packet broadcasting and cycle message network scheduling functions; the network controller times a bus network period, sends a period starting packet when each new period arrives, each scheduling period is divided into a determined scheduling section and a competitive scheduling section, the determined scheduling section is located at the starting position of each period, sends a network low-priority starting packet after the determined scheduling section is completed, and switches the bus network period into the competitive scheduling section; for the messages to be scheduled with high priority, scheduling can be carried out at any time in the determined scheduling section and the competitive scheduling section, and other messages with low priority which are currently executed are interrupted; for messages to be scheduled with low priority, they can be scheduled only in the contention scheduling segment.

2. The cycle and priority based bus scheduling method of claim 1, wherein the certain scheduling segment is used for transmitting a small data block having a specific cycle, and the contention scheduling segment is used for transmitting a large data block having a specific cycle.

3. The method for bus scheduling based on cycles and priorities as claimed in claim 2, wherein the transmission of the low priority aperiodic message has a priority greater than the periodic message in the contention scheduling segment and less than the high priority aperiodic message.

4. The cycle and priority based bus scheduling method of claim 3, wherein the network controller further broadcasts the remaining time of the current bus cycle via a network synchronization packet, each network node reloads its own cycle time down counter after receiving the network synchronization packet, and waits for the next cycle to start transmission when the time value of the down counter is not sufficient to send a non-periodic message.

5. The method of claim 4, wherein the small data blocks with a specific period are transmitted in a time-triggered manner in the deterministic scheduling segments, and are transmitted constantly once per bus period.

6. A method according to claim 5, wherein large blocks of data with a specific period are transmitted in a contention scheduling section in an event-triggered manner, a plurality of possible large blocks of data are polled in each bus period, if any, until the end of the bus period, and if the blocks are large, the polling in the next period can be continued for transmission over several consecutive bus periods.