Offload control device, offload control method, and offload control program

Abstract

An offload control unit (24) controls whether to execute a target task in an external processing device upon arriving at a time preceding a reference time at which a time slot starts, the time slot corresponding to the data type of input data of the target task in time-division communication in which time slots available for communication are determined according to data type. The offload control unit (24) controls whether to execute the target task in the external processing device on the basis of the time remaining until a deadline of the target task, a predicted internal time that is the predicted execution time when the target task is executed by an internal processing device, and a predicted external time that is the predicted execution time when the target task is executed by the external processing device.

Description

Off-road control device, off-road control method, and off-road control program

[0001] The present disclosure relates to a technique for allocating tasks using an external computing device.

[0002] Patent Document 1 describes a method of allocating tasks to processor cores in consideration of the task execution order, task execution cycle, and communication costs between processor cores, thereby aiming to meet the deadlines of each task.

[0003] Japanese Patent Application Laid-Open No. 2015-225396

[0004] The technology described in Patent Document 1 can control task allocation in a processor core within a CPU. CPU stands for Central Processing Unit. However, the technology described in Patent Document 1 does not take into consideration control including external computing devices. In particular, the technology described in Patent Document 1 cannot optimize computing device allocation or reduce processing delays related to allocation in order to meet the deadlines of each task in an environment where it is unknown when input data will be available.

[0005] In an external computing device such as a GPU, even if a high-priority task becomes executable, it may be delayed because it must wait until the previously executed task is completed. GPU stands for Graphics Processing Unit. This delay can cause deadlines to be missed. To address this issue, a solution can be considered that restricts the use of the target external computing device by other tasks. However, if the timing of acquisition of input data for the target task is unknown, it is not possible to determine the timing of use of the external computing device for calculations using the input data. As a result, use of the target external computing device will be restricted for a long period of time. This is inefficient in terms of computing resource utilization, and it may take longer for other tasks to complete processing, resulting in missed deadlines.

[0006] Furthermore, when using an external computing device such as a GPU, pre-processing is required before executing a target task, such as allocating memory on the external computing device and transferring data to the memory. If the timing of input data acquisition is known, the timing of task execution can be determined. Therefore, it is possible to consider shortening the task processing completion time by performing pre-processing immediately before the execution timing. Note that the data transferred in this data transfer is data other than the input data. However, if the timing of input data acquisition is unknown, pre-processing cannot be performed immediately before task execution. If pre-processing is performed in advance without considering the timing of task execution, it may lead to memory congestion on the external computing device, making it impossible to execute other tasks.

[0007] The present disclosure aims to make it possible to allocate tasks to computing devices, including external computing devices, in a way that makes it easier to meet task deadlines.

[0008] The offload control device according to the present disclosure includes: a predicted time management unit that manages a predicted internal time, which is a predicted execution time when a target task is executed on an internal computing device, and a predicted external time, which is a predicted execution time when the target task is executed on an external computing device; and an offload control unit that controls whether to cause the external computing device to execute the target task based on the remaining time until the deadline of the target task at a point before a reference time at which a time slot corresponding to a data type of input data of the target task starts in time-division communication in which time slots available for communication are determined according to data type, and the predicted internal time and the predicted external time managed by the predicted time management unit.

[0009] In the present disclosure, whether or not to cause an external computing device to execute a target task is controlled using the remaining time until the deadline of the target task at a point before the reference time at which the time slot corresponding to the data type of input data starts, the predicted internal time, and the predicted external time. This makes it possible to allocate tasks to computing devices, including the external computing device, so that task deadlines are more likely to be met.

[0010] 1 is a hardware configuration diagram of an off-road control device 10 according to a first embodiment. 2 is a functional configuration diagram of an off-road control device 10 according to the first embodiment. 3 is a flowchart of overall processing by the off-road control device 10 according to the first embodiment. 4 is a flowchart of first control processing according to the first embodiment. 5 is a flowchart of second control processing according to the first embodiment. 6 is a flowchart of third control processing according to the first embodiment. 7 is a flowchart of first control processing according to the second embodiment. 8 is a flowchart of third control processing according to the second embodiment. 9 is a flowchart of first control processing according to the third embodiment. 10 is a flowchart of overall processing by the off-road control device 10 according to a fourth embodiment.

[0011] First Embodiment *** Description of Configuration *** The hardware configuration of an off-road control device 10 according to the first embodiment will be described with reference to Figure 1. The off-road control device 10 is a computer. The off-road control device 10 includes the following hardware: an internal calculation unit 11, a memory 12, a storage device 13, and an external calculation unit 14.

[0012] The internal processing unit 11 is a processing unit that mainly performs processing. A specific example of the internal processing unit 11 is a CPU.

[0013] The memory 12 is a main storage device used as a work area for the internal processing unit 11. A specific example of the memory 12 is a RAM. RAM is an abbreviation for Random Access Memory.

[0014] The storage device 13 is a storage device that stores program images such as an OS and application programs. OS is an abbreviation for Operating System. Specific examples of the storage device 13 include an SSD or HDD. SSD is an abbreviation for Solid State Drive. HDD is an abbreviation for Hard Disk Drive. The storage device 13 may be a portable recording medium such as an SD (registered trademark) memory card, CompactFlash (registered trademark), NAND flash, a flexible disk, an optical disk, a compact disk, a Blu-ray (registered trademark) disk, or a DVD. SD is an abbreviation for Secure Digital. DVD is an abbreviation for Digital Versatile Disk.

[0015] The external processing unit 14 is a processing unit provided separately from the internal processing unit 11. A specific example of the external processing unit 14 is a GPU.

[0016] The functional configuration of the offload control device 10 according to the first embodiment will be described with reference to FIG. 2 . The offload control device 10 includes, as functional components, a communication management unit 21, a deadline management unit 22, a predicted time management unit 23, and an offload control unit 24. The functions of each functional component of the offload control device 10 are implemented by software. The storage device 13 stores programs that implement the functions of each functional component of the offload control device 10. These programs are loaded into the memory 12 by the internal processing unit 11 and executed by the internal processing unit 11. In this way, the functions of each functional component of the offload control device 10 are implemented.

[0017] 1 shows only one internal processing unit 11. However, there may be multiple internal processing units 11, and the multiple internal processing units 11 may cooperate to execute programs that realize the respective functions.

[0018] ***Description of Operation*** The operation of the off-road control device 10 according to the first embodiment will be described with reference to Figures 3 to 6. The operation procedure of the off-road control device 10 according to the first embodiment corresponds to the off-road control method according to the first embodiment. Furthermore, the program that realizes the operation of the off-road control device 10 according to the first embodiment corresponds to the off-road control program according to the first embodiment.

[0019] Here, we assume that the environment uses time-division communication, where available time slots are determined according to the data type. Therefore, input data for a task is acquired only in the time slot corresponding to the data type of the input data. However, it is not known when the input data for a task will be acquired.

[0020] The overall processing of the offload control device 10 according to the first embodiment will be described with reference to FIG. 3 . (Step S101: Communication Management Processing) The communication management unit 21 manages time information for communication time slots corresponding to the data type of input data for each task in time-division communication. The offload control unit 24 acquires time information for time slots corresponding to the data type of input data for the target task from the communication management unit 21. The time slot corresponding to the data type of input data is called the target slot. The communication management unit 21 waits until the reference time before the start time of the time slot indicated by the time information. In other words, the communication management unit 21 waits until the reference time before the start time of the target slot. Then, the communication management unit 21 proceeds to step S102 when the reference time before the start time of the target slot is reached. The reference time is a time set in advance. For example, the reference time is set to a time during which use of the external computing device 14 is permitted for other tasks.

[0021] (Step S102: Information Acquisition Processing (Deadline Management Processing, Predicted Time Management Processing)) The deadline management unit 22 manages the remaining time until the deadline of each task. The offload control unit 24 acquires the remaining time until the deadline of the target task from the deadline management unit 22. In other words, the offload control unit 24 acquires the remaining time until the deadline of the target task at a point in time before the reference time at which the target slot starts. The predicted time management unit 23 manages predicted internal time, which is the predicted execution time when the target task is executed by the internal calculation device 11, and predicted external time, which is the predicted execution time when the target task is executed by the external calculation device 14. The offload control unit 24 acquires the predicted internal time and predicted external time from the predicted time management unit 23.

[0022] (Step S103: Offload Control Processing) The offload control unit 24 determines how to execute the target task when input data for the target task is acquired in the target slot, based on the remaining time acquired in step S102, the predicted internal time, and the predicted external time. Specifically, the offload control unit 24 controls whether or not to have the external computing device 14 execute the target task. Furthermore, when having the external computing device 14 execute the target task, the offload control unit 24 controls whether or not to allow the external computing device 14 to be used by a task other than the target task.

[0023] In the first embodiment, the description is based on the assumption that the predicted external time is shorter than the predicted internal time. Under this assumption, the offload control unit 24 determines to have the external computing device 14 execute the target task when the predicted internal time is longer than the remaining time. In other words, the offload control unit 24 determines to have the external computing device 14 execute the target task if the deadline will not be met unless the target task is executed by the external computing device 14. If it is determined that the target task should be executed by the external computing device 14, the offload control unit 24 determines whether to allow other tasks to use the external computing device 14 based on the remaining time and the predicted external time. Specifically, if a delay due to waiting for use of the external computing device 14 is not allowed, the offload control unit 24 determines that use of the external computing device 14 by other tasks is not allowed. For example, the offload control unit 24 may determine that a delay is allowed if the remaining time is longer than the predicted external time by at least a threshold time.

[0024] If the offload control unit 24 determines that the target task must be executed by the external computing device 14 and that use of the external computing device 14 by other tasks is not permitted, the offload control unit 24 proceeds to step S110. That is, if the target task must be executed by the external computing device 14 in order to meet the deadline and delays due to waiting for use of the external computing device 14 are not permitted, the offload control unit 24 proceeds to step S110. If the offload control unit 24 determines that the target task must be executed by the external computing device 14 and that use of the external computing device 14 by other tasks is permitted, the offload control unit 24 proceeds to step S120. That is, if the target task must be executed by the external computing device 14 in order to meet the deadline but delays due to waiting for use of the external computing device 14 are permitted, the offload control unit 24 proceeds to step S120. If the offload control unit 24 determines that the target task must be executed by the external computing device 14 in order to meet the deadline but delays due to waiting for use of the external computing device 14 are permitted, the offload control unit 24 proceeds to step S130. That is, if the target task can be executed in time for the deadline even if it is executed by the internal processing unit 11, the offload control unit 24 advances the process to step S130.

[0025] The first control process (step S110 in FIG. 3) according to the first embodiment will be described with reference to FIG. 4. (Step S111: Restriction Process) The offload control unit 24 sets a restriction on the use of the external computing device 14 by other tasks. That is, the offload control unit 24 prevents other tasks from using the external computing device 14 at a point in time before the reference time when the target slot starts. In this way, when input data for the target task is acquired in the target slot, the offload control unit 24 prevents the target task from being prevented from using the external computing device 14 by the other tasks.

[0026] (Step S112: Acquisition Determination Process) The offload control unit 24 determines whether input data for the target task has been acquired in the target slot. If input data has been acquired, the offload control unit 24 proceeds to step S113. On the other hand, if input data has not been acquired, the offload control unit 24 skips step S113 and proceeds to step S114.

[0027] (Step S113: Computation Processing) The offload control unit 24 instructs the external computing device 14 to execute the target task. As a result, the target task is executed by the external computing device 14. When execution of the target task starts, the offload control unit 24 proceeds to step S114.

[0028] (Step S114: Restriction Release Processing) The offload control unit 24 releases the usage restriction set in step S111. That is, if input data for the target task is acquired in the target slot, the offload control unit 24 releases the usage restriction when execution of the target task by the external computing device 14 begins. On the other hand, if input data for the target task is not acquired in the target slot, the offload control unit 24 immediately releases the usage restriction.

[0029] The second control process (step S120 in FIG. 3) according to the first embodiment will be described with reference to FIG. 5. (Step S121: Acquisition Determination Process) The offload control unit 24 determines whether input data for the target task has been acquired in the target slot. If input data has been acquired, the offload control unit 24 proceeds to step S122. On the other hand, if input data has not been acquired, the offload control unit 24 skips step S122 and ends the process.

[0030] (Step S122: Computation Processing) The offload control unit 24 instructs the external computing device 14 to execute the target task. As a result, the target task is executed by the external computing device 14. Once the target task has started, the offload control unit 24 ends the processing.

[0031] The third control process (step S130 in FIG. 3) according to the first embodiment will be described with reference to FIG. 6. (Step S131: Acquisition Determination Process) The offload control unit 24 determines whether input data for the target task has been acquired in the target slot. If input data has been acquired, the offload control unit 24 proceeds to step S132. On the other hand, if input data has not been acquired, the offload control unit 24 skips step S132 and ends the process.

[0032] (Step S132: Computation Processing) The offload control unit 24 instructs the internal processing unit 11 to execute the target task. As a result, the target task is executed by the internal processing unit 11. When the target task is started, the offload control unit 24 ends the processing.

[0033] ***Effects of First Embodiment*** As described above, the offload control device 10 according to the first embodiment controls whether or not to have the external computation device 14 execute the target task, using the remaining time until the deadline of the target task at the point in time before the reference time at which the target slot starts, the predicted internal time, and the predicted external time. This makes it possible to preferentially allocate an external computation device 14 capable of high-speed processing to a task whose deadline is approaching. As a result, task deadlines are more likely to be met.

[0034] When a deadline is approaching, the offload control device 10 according to the first embodiment restricts the use of the external computing device by other tasks before obtaining input data for the target task. This reduces delays caused by the target task waiting for an available external computing device 14. Furthermore, the offload control device 10 according to the first embodiment removes this usage restriction when it is determined that the target task has started to be executed on the external computing device 14 or that input data is no longer available. This minimizes the duration of the usage restriction and reduces the impact on other tasks.

[0035] ***Other Configurations*** <Modification 1> In the first embodiment, each functional component is realized by software. However, in Modification 1, each functional component may be realized by hardware. The differences between Modification 1 and the first embodiment will be described below.

[0036] When each functional component is realized by hardware, the off-road control device 10 includes an electronic circuit, which is a dedicated circuit for realizing the function of each functional component.

[0037] Possible electronic circuits include a single circuit, a composite circuit, a programmed processor, a parallel programmed processor, a logic IC, a GA, an ASIC, and an FPGA. GA stands for Gate Array. ASIC stands for Application Specific Integrated Circuit. FPGA stands for Field-Programmable Gate Array. Each functional component may be realized by a single electronic circuit, or each functional component may be distributed across multiple electronic circuits.

[0038] <Modification 2> As a modification 2, some of the functional components may be realized by hardware, and other functional components may be realized by software.

[0039] The internal processing unit 11, the external processing unit 14, and the electronic circuit are collectively referred to as a processing circuit. That is, the functions of the respective functional components are realized by the processing circuit.

[0040] Furthermore, the term "unit" in the above description may be read as a "circuit," "step," "procedure," "process," or "processing circuit."

[0041] Embodiment 2. Embodiment 2 differs from embodiment 1 in that advance preparation is performed on the arithmetic device that performs the target task. In embodiment 2, this difference will be explained, and explanation of the same points will be omitted.

[0042] ***Description of Operation*** The first control process (step S110 in FIG. 3) according to the second embodiment will be described with reference to FIG. 7. The process of step S211 is the same as the process of step S111 in FIG. 4. The processes of steps S213 and S214 are the same as the processes of steps S112 and S113 in FIG. 4. The process of step S216 is the same as the process of step S114 in FIG. 4.

[0043] (Step S212: Advance Preparation Process) The offload control unit 24 performs advance preparation for the external computing device 14 to execute the target task. That is, the offload control unit 24 performs advance preparation at a time before the reference time of the target slot. The advance preparation includes, for example, allocating memory.

[0044] (Step S215: Preparation Cancellation Processing) The offload control unit 24 cancels the advance preparation performed in step S212. That is, the offload control unit 24 cancels the advance preparation if the input data of the target task is not acquired in the target slot. For example, if the advance preparation was memory allocation, the offload control unit 24 releases the allocated memory.

[0045] The second control process (step S120 in FIG. 3) according to the second embodiment will be described with reference to FIG. 8. The processes in steps S222 and S223 are the same as the processes in steps S121 and S122 in FIG.

[0046] (Step S221: Advance Preparation Process) As in step S212 of FIG. 7, the offload control unit 24 makes advance preparations for the external computing device 14 to execute the target task.

[0047] (Step S224: Preparation Cancellation Process) As in step S215 of FIG. 7, the offload control unit 24 cancels the advance preparation performed in step S221.

[0048] The third control process (step S130 in FIG. 3) according to the second embodiment will be described with reference to FIG. 9. The processes in steps S232 and S233 are the same as the processes in steps S131 and S132 in FIG.

[0049] (Step S231: Advance Preparation Process) The offload control unit 24 makes advance preparations for the internal processing unit 11 to execute the target task.

[0050] (Step S234: Preparation Cancellation Process) The offload control unit 24 cancels the advance preparation performed in step S231.

[0051] ***Effects of the Second Embodiment*** The offload control device 10 according to the second embodiment performs advance preparations for executing a target task before acquiring input data for the target task. This enables the target task to be executed smoothly, and the target task can be completed more quickly. As a result, it becomes easier to meet the deadline of the target task.

[0052] Embodiment 3. Embodiment 3 differs from embodiment 1 in that the use restriction of other tasks is realized by using a flag. In embodiment 3, this difference will be explained, and explanation of the same points will be omitted.

[0053] The first control process (step S110 in FIG. 3) according to the third embodiment will be described with reference to FIG. 10. The processes in steps S312 and S313 are the same as the processes in steps S112 and S113 in FIG.

[0054] In the third embodiment, it is assumed that other tasks will not use the external processing unit if the reservation flag is set. In other words, other tasks will check the reservation flag before using the external processing unit 14, and if the reservation flag is set, they will wait or perform other processing until the reservation flag is reset.

[0055] (Step S311: Restriction processing) The offload control unit 24 sets a reservation flag. That is, the offload control unit 24 sets the reservation flag when the time arrives before the reference time of the target slot. This restricts the use of the external processing unit 14 by other tasks, and allows the target task to use the external processing unit 14 preferentially after acquiring input data.

[0056] (Step S314: Restriction Release Processing) The offload control unit 24 resets the reservation flag.

[0057] ***Effects of the Third Embodiment*** As described above, the offload control device 10 according to the third embodiment sets a reservation flag before acquiring input data for a target task when the deadline is approaching. This makes it possible to reduce delays caused by the target task waiting for an available external computing device 14 when the input data is acquired. Furthermore, the offload control device 10 according to the third embodiment resets the reservation flag when it is determined that the target task has started to be executed in the external computing device 14 or that input data cannot be acquired. This makes it possible to minimize the period of usage restriction and reduce the impact on other tasks.

[0058] Embodiment 4. Embodiment 4 differs from embodiment 1 in that the predicted external time is longer than the predicted internal time. In embodiment 4, this difference will be explained, and explanation of the same points will be omitted.

[0059] ***Description of Operation*** The overall processing of the off-road control device 10 according to the fourth embodiment will be described with reference to Fig. 11. The processing in steps S401 and S402 is the same as the processing in steps S101 and S102 in Fig. 3. The processing in steps S410 to S430 is the same as the processing in steps S110 to S130 in Fig. 3.

[0060] (Step S403: Offload Control Processing) As in step S103 of FIG. 3 , the offload control unit 24 determines how to execute the target task when input data for the target task is acquired in the target slot, based on the remaining time, the predicted internal time, and the predicted external time. Under the assumption that the predicted external time is longer than the predicted internal time, the offload control unit 24 determines to have the external computing device 14 execute the target task if the predicted external time is shorter than the remaining time. In other words, the offload control unit 24 determines to have the external computing device 14 execute the target task if the deadline can be met even if the target task is executed by the external computing device 14. If it is determined that the target task should be executed by the external computing device 14, then, as in step S103 of FIG. 3 , the offload control unit 24 determines whether to allow other tasks to use the external computing device 14, based on the remaining time and the predicted external time.

[0061] If the offload control unit 24 determines that the external computing device 14 should execute the target task and that use of the external computing device 14 by other tasks cannot be permitted, the offload control unit 24 proceeds to step S410. That is, if the target task can be executed on the external computing device 14 and the deadline can be met without a delay due to waiting for use of the external computing device 14, the offload control unit 24 proceeds to step S410. If the offload control unit 24 determines that the external computing device 14 should execute the target task and that use of the external computing device 14 by other tasks can be met, the offload control unit 24 proceeds to step S420. That is, if the target task can be executed on the external computing device 14 and the deadline can be met even if there is a delay due to waiting for use of the external computing device 14, the offload control unit 24 proceeds to step S420. If the offload control unit 24 determines that the target task should not be executed on the external computing device 14, the offload control unit 24 proceeds to step S430. That is, if the target task must be executed by the internal processing unit 11 in order to meet the deadline, the offload control unit 24 advances the process to step S430.

[0062] ***Effects of the Fourth Embodiment*** As described above, when the predicted external time is longer than the predicted internal time, the offload control device 10 according to the fourth embodiment can preferentially allocate the internal processing unit 11, which is capable of high-speed processing, to a task whose deadline is approaching. As a result, task deadlines are more likely to be met.

[0063] The embodiments and modifications of the present disclosure have been described above. Some of these embodiments and modifications may be combined and implemented. Furthermore, one or more of them may be implemented partially. Note that the present disclosure is not limited to the above embodiments and modifications, and various modifications are possible as needed.

[0064] 10 Offload control device, 11 Internal calculation unit, 12 Memory, 13 Storage device, 14 External calculation unit, 21 Communication management unit, 22 Deadline management unit, 23 Predicted time management unit, 24 Offload control unit.

Claims

1. An offload control device comprising: a predicted time management unit that manages a predicted internal time, which is a predicted execution time when a target task is executed in an internal computing device, and a predicted external time, which is a predicted execution time when the target task is executed in an external computing device; and an offload control unit that controls whether to cause the external computing device to execute the target task based on the remaining time until the deadline of the target task at a point before a reference time when a time slot corresponding to the data type of input data of the target task starts in time-division communication in which time slots available for communication are determined according to data type, and the predicted internal time and predicted external time managed by the predicted time management unit.

2. The offload control device according to claim 1, wherein the offload control unit causes the external computing device to execute the target task when the predicted external time is shorter than the predicted internal time and the predicted internal time is longer than the remaining time.

3. An offload control device according to claim 1 or 2, wherein the offload control unit causes the external computing device to execute the target task when the predicted external time is longer than the predicted internal time and the predicted external time is shorter than the remaining time.

4. An offload control device according to any one of claims 1 to 3, wherein when the offload control unit causes the external computing device to execute the target task, it controls whether or not to allow the external computing device to be used by a task other than the target task, based on the remaining time and the predicted external time.

5. The offload control device according to claim 4, wherein, when the offload control unit does not allow other tasks different from the target task to use the external computing device, it restricts the other tasks from using the external computing device at a time before the reference time of the target slot, which is a time slot corresponding to the data type of input data of the target task.

6. An offload control device according to claim 5, wherein the other task does not use the external computing device when a reservation flag is set, and the offload control unit sets the reservation flag when the other task does not allow use of the external computing device at a time before the reference time of the target slot.

7. The offload control device according to claim 5 or 6, wherein the offload control unit releases the usage restriction when the input data for the target task is acquired in the target slot and the external computing device starts executing the target task, and immediately releases the usage restriction when the input data for the target task is not acquired in the target slot.

8. An offload control device according to any one of claims 1 to 5, wherein the offload control unit makes advance preparations for executing the target task when a time before the reference time of a target slot, which is a time slot corresponding to the data type of input data of the target task, arrives, and cancels the advance preparations if the input data of the target task is not acquired in the target slot.

9. An offload control method in which a computer manages a predicted internal time, which is the predicted execution time when a target task is executed in an internal computing device, and a predicted external time, which is the predicted execution time when the target task is executed in an external computing device, and the computer controls whether to cause the external computing device to execute the target task based on the remaining time until the deadline of the target task at a point before a reference time when a time slot corresponding to the data type of input data of the target task starts in time-division communication in which communication time slots are determined according to data type, and the predicted internal time and predicted external time.

10. An offload control program that causes a computer to function as an offload control device that performs a predicted time management process that manages a predicted internal time, which is the predicted execution time when a target task is executed in an internal computing device, and a predicted external time, which is the predicted execution time when said target task is executed in an external computing device; and an offload control process that controls whether or not to cause said external computing device to execute said target task, based on the remaining time until the deadline of said target task at a point before a reference time when a time slot corresponding to the data type of input data of said target task starts in time-division communication in which time slots available for communication are determined according to data type, and the predicted internal time and predicted external time managed by said predicted time management process.

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