JP3189810B2 - QoS controller - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a QoS control device, a QoS control method, and a recording medium suitable for an embedded real-time system.

[0002]

2. Description of the Related Art With the development of microprocessor technology,
MPU (Micro Proc) is used in many personal electronic devices such as audio / video equipment, televisions, mobile phones, electronic musical instruments, game machines, washing machines, air conditioners, and lighting equipment.
essor Unit) and one-chip microcomputer (MCU; Micro Cont)
roller unit) and other microcomputers. Hereinafter, a system in which a microcomputer is incorporated for controlling devices is referred to as an “embedded system”.
Such an embedded system has been developed with the ITRON (Industr
ial TRON (TRON: The Real-time Operating system Nucle
us)) and the like, a case using a real-time OS (Operating System) is becoming common.

For example, an embedded system using such a real-time OS in a car navigation device (hereinafter, referred to as an “embedded real-time system”).
Then, CD-ROM (Compact Disk Read-Only Memor)
y) and device control such as sensors, as well as Web (World Wid
e Web) It can also provide multimedia services such as displaying pages, playing videos, and playing audio. In such an embedded real-time system, not only must resources of the limited system be minimized due to cost and space issues, but resources must be allocated preferentially to real-time tasks for control. . For this reason, in the embedded real-time system, it is necessary to process the multimedia service task by efficiently using the remaining resources.

Recently, in order to utilize limited resources efficiently in embedded real-time systems,
The quality of service of the task according to the amount of available resources (Q
A QoS control technique for changing the quality of service (oS) is applied. QoS control refers to lowering the service quality (calculation accuracy, control accuracy) to reduce the load when the load on the system exceeds an assumed maximum value. Hereinafter, the QoS control will be described using a distributed multimedia system as an example.

[0005] QoS control has traditionally been used in distributed systems that provide multimedia services. In a distributed multimedia system, generally, an unspecified number of user programs are connected to a server. That is, the user program connects to the server via the network, receives multimedia data such as images and sounds stored in the storage device of the server or generated by the server, and displays it on a predetermined screen. And so on.

However, since the resources of the server and the communication bandwidth of the network are limited, when a large number of user programs request a multimedia service and the server or the network is overloaded, it is not always necessary. In some cases, the QoS required by the user program cannot be provided. Further, even when the server can provide high QoS, if the capability of the terminal on the user side is low or if sufficient processing cannot be performed in an overloaded state, receiving a high-quality service may be useless. In such a case, QoS control is performed to reduce the load on the server or the network or to provide a service that matches the performance of the user terminal. On the other hand, when the load on the server, the network, and the terminal on the user side is reduced, the QoS is also increased to increase the QoS.
Control is performed.

In the QoS control method used in such a distributed multimedia system, for example, when allocating resources for each user, the QoS is determined by negotiation between a user program and a server. The procedure of this negotiation is shown below.

First, when connecting to a server, the user program requests a receivable QoS. The server compares the current amount of resources that can be provided with the QoS request amount from the user program, and if it can be provided, accepts the QoS request, allocates resources to the user program, and provides a service.

On the other hand, the Q required by the user program
When the oS cannot be provided, the server presents the available QoS to the user program. The user program either accepts the offered QoS or renews it to the server (generally, the QoS presented by the server side).
(Lower than S) QoS. The above procedure is repeated until the server or user program accepts the offered QoS. After the QoS request is accepted or the QoS presented by the server is accepted, the user program performs a process corresponding to the QoS.

[0010] When the server or the network is overloaded, or conversely, when the server or the network is under a low load, the server sends a QoS change request to the user program. In response to this QoS change request, the user program newly requests the server for QoS. Thereafter, the same processing as the processing when the above-mentioned user program connects to the server is performed. On the other hand, when the user program is overloaded or, conversely, is under low load, the user program sends a QoS change request. This also performs the same processing as the processing when the user program connects to the server.

In the QoS control method used in the distributed multimedia system, all user programs are of the same type. As a policy for allocating resources to each user program, a method is used such that resource allocation is fair, or a method of allocating resources according to a predetermined ratio is used.

By using the QoS control method described above in an embedded real-time system,
For example, when providing a high-quality multimedia service, a task for the multimedia service can be processed by efficiently using the remaining resources.

[0013]

However, in the above-described conventional QoS control method, a certain amount of time is required for the QoS control processing. For example, in the above-described distributed multimedia system, since an unspecified number of user programs connect to the server, it has been impossible for the server to grasp the QoS request amounts of all user tasks in advance. For this reason, in the conventional QoS control method,
By negotiating with the user program, the server checks whether the QoS request amount of the user program is within the available resource amount and determines resource allocation. For this negotiation, communication and synchronization are required, and these processes involve a context switch, so that it took some time. For this reason, QoS
In a built-in real-time system using a control method, there is a problem that a high-speed processing of a user task (application task) is required, but a processing delay cannot be prevented.

In the conventional QoS control system described above, it is difficult to preferentially allocate resources only to a specific task. For example, in the above-described distributed multimedia system, since all the user programs to be subjected to QoS control are the same type of programs that handle audio and video streams, resources are distributed fairly, or according to a predetermined ratio. QoS control for allocating resources has been performed. For this reason, in an embedded real-time system using the QoS control method, there is a problem that resources cannot be preferentially allocated to a real-time task for control, so that control delay cannot be prevented.

[0015] The present invention has been made in view of the above-described circumstances, and has been described in an embedded real-time system.
QoS control device capable of high-speed control, QoS
It is an object to provide a control method and a recording medium.

[0016]

Means for Solving the Problems] To achieve the above object, QoS control device according to a first aspect of the invention, co
Under the control of the OS that manages resources in the computer system
Quality of service (Qo
A QoS control device for controlling the S), predetermined
Resources for each task corresponding to each class in the QoS class
Quota storage means for storing a quota of sources, and a computer
Stores a level value indicating the current grade of QoS in the system
A level value storage means for storage in said level value storage unit
Stored in the quota storage means determined from the set level value.
Where each task is started according to the allocated resource
Use to obtain the resource utilization rate from the computer system
Rate acquisition means, and the resources acquired by the utilization rate acquisition means.
So that the utilization rate of the source falls within the predetermined range.
Changes the level value stored in the level value storage means,
Stored in the quota storage means determined from the updated level value.
Change the QoS for the task according to the allocated amount
QoS control means and at least startup and wake-up
Resources in the computer system must be used regularly.
Effective task management means for managing effective tasks
For example, the utilization rate acquisition unit may include the effective task management unit.
Computer system for managed and valid tasks
Acquiring the utilization rate of the resources in the system, and the QoS control means:
The utilization rate of the resource acquired by the utilization rate acquiring means is predicted.
Above the specified maximum value,
Resources for at least one task stored in storage means
In order to reduce the quota of the source, the level value storage means
Change the stored level value to the corresponding task
Changing the QoS .

According to the present invention, the quota storage means is
To a defined QoS class (eg levels 0 to 6)
Of resources for each task corresponding to each class in the
(For example, required resource amount). The level value storage means
Level indicating the current grade of QoS in the computer system.
The default value. The utilization rate acquisition means is a level value storage means
Stored in quota storage means determined from the level value stored in
Each task is started according to the allocated resource quota
Obtain the resource utilization from the computer system.
The QoS control means controls the resources acquired by the utilization rate acquiring means.
To ensure that the source utilization falls within a predetermined range.
Change and change the level value stored in the bell value storage means.
Quota stored in the quota storage means determined from the set level value
Change the QoS for the task according to the amount. Effective
The disk management means should be at least started and
Resources in the computer system will be used regularly
Manage available tasks. And the utilization rate acquisition means,
For valid tasks managed by the valid task management means
To obtain the utilization rate of the resources in the computer system,
The QoS control means controls the resources acquired by the utilization rate acquiring means.
When the utilization of the source exceeds a predetermined maximum
The at least one task stored in the quota storage means.
Level notation to reduce the amount of resources allocated to
Change the level value stored in the storage device and execute the corresponding task
Change the QoS for. As a result, QoS control can be performed at high speed.

In order to achieve the above object, a second aspect of the present invention is provided.
The QoS control device according to the aspect, the computer system
Start up under the management of the OS that manages resources in the
QoS that controls the quality of service (QoS) for disks
An S-control device that meets a predetermined QoS class
The resource quota for each task corresponding to each class
Quota storage means and QoS in a computer system
Level value storage means for storing the level value indicating the current grade of
And the level and the level value stored in the level value storage means.
The resource quota stored in the quota storage means
Computer system on which each task is started
From the utilization rate obtaining means for obtaining the utilization of resources, the
The utilization rate of the resources acquired by the utilization rate acquisition means is predetermined.
The level value storage means so as to fall within the set range.
Change the level value stored in
According to the quota stored in the quota storage means determined
Control means for changing the QoS for a task
And the computer system at least ends and waits for processing.
Invalid tasks that constantly use resources in the system
And a disable task management means for managing, collected the utilization
The obtaining means is an invalid task managed by the invalid task managing means.
Use of resources in the computer system, excluding tasks
Rate, and the QoS control means performs the utilization rate acquisition step.
The utilization rate of the resources acquired by the step is a predetermined minimum
If the value does not exceed the value, it is stored in the quota storage means.
Resources allocated to at least one task
The level stored in the level value storage means.
Change the QoS value for the corresponding task
That, characterized in that.

According to the present invention, the quota storage means stores
To a defined QoS class (eg levels 0 to 6)
Of resources for each task corresponding to each class in the
(For example, required resource amount). The level value storage means
Level indicating the current grade of QoS in the computer system.
The default value. The utilization rate acquisition means is a level value storage means
Stored in quota storage means determined from the level value stored in
Each task is started according to the allocated resource quota
Obtain the resource utilization from the computer system.
The QoS control means controls the resources acquired by the utilization rate acquiring means.
To ensure that the source utilization falls within a predetermined range.
Change and change the level value stored in the bell value storage means.
Quota stored in the quota storage means determined from the set level value
Change the QoS for the task according to the amount. Invalid
The disk management means must execute at least
Stops constantly using resources in the computer system
Manage disabled tasks. And the utilization rate acquisition means,
Excluding invalid tasks managed by invalid task management means
To obtain the utilization rate of the resources in the computer system,
The QoS control means controls the resources acquired by the utilization rate acquiring means.
If the utilization of the source does not exceed a predetermined minimum
The at least one task stored in the quota storage means.
Level notation so that resources allocated to
Change the level value stored in the storage device and execute the corresponding task
Change the QoS for. As a result , QoS control can be performed at high speed.

[0020]

[0021]

[0022]

[0023]

[0024]

[0025]

[0026]

[0027]

[0028]

[0029]

[0030]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a QoS control device according to a first embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing a Q according to the first embodiment of the present invention.
FIG. 1 is a block diagram illustrating an example of a configuration of a system incorporating an oS control device. The system incorporating the QoS control device shown in FIG. 1 includes a CPU 1, a memory 2, and a ROM 3.

CPU (Central Processing Unit) 1
Loads a program such as the OS 10 stored in the ROM 3 in advance into the memory 2 and performs various processes described later.

The memory 2 is a RAM having a predetermined capacity.
(Random Access Memory), the OS 10 stored in the ROM 3 is loaded, and the application tasks 20-1 to 20-n are executed on the OS 10.

The ROM 3 stores programs such as the OS 10 in advance. Note that the ROM 3 is for storing programs such as the OS 10 and may be replaced with a secondary storage device such as a flash memory or a hard disk.

The CPU 1, the memory 2, and the RO
M3 is an integrated one-chip microcomputer (MCU)
Etc.).

The OS 10 has a real-time kernel 19
A QoS control task 11, an idle time monitoring task 12, a DL (deadline) miss processing task 13,
API30.

The real-time kernel 19 provides a basic function in the OS 10. More specifically, the real-time kernel 19 includes, in addition to functions such as memory management, task management, and inter-task synchronization provided by a general OS, a task cycle which is a characteristic function of the real-time kernel. Provide execution function.

For example, in μITRON3.0 (micro ITRON3.0 specification), which is one of the typical real-time kernels, a periodic execution function which is a feature thereof is provided as a periodic handler. In this cyclic handler, the function registered by the user is executed by the kernel at regular intervals. Generally, a real-time kernel counts up a timer or the like in the kernel using a periodic timer interrupt. As a part of the timer interrupt processing, the counter for the cyclic handler is decremented. When the counter becomes zero, the cyclic handler executes the function registered by the user. The real-time kernel can execute the task periodically by starting or waking up the task as the processing of the cyclic handler. In addition,
Regarding μITRON 3.0, “μITRON 3.0
Details are described in "Revised New Standard Handbook" (supervised by Ken Sakamura: Personal Media).

The real-time kernel 19 of the QoS control device of the present invention also provides a cyclic handler similar to μITRON 3.0. In the QoS control device of the present invention, the cyclic handler is also used for detecting a DL (deadline) error. Specifically, Q of the present invention
In the oS control device, a function for calling the DL miss processing task 13 is registered in advance in a cyclic handler for periodically executing the task. As a cycle of the handler, a deadline time indicating a final deadline (relative time from the start time of the task) expected to complete the processing of the task is given. As a result, when the deadline time elapses from the scheduled start time of the task (the time at which the cyclic handler for periodic execution is executed), the cyclic handler for deadline miss detection is executed. Deadline processing is performed.

The QoS control task 11 is an OS module for performing QoS control, and has a higher priority than the application tasks 20-1 to 20-n. The QoS control task 11 has a QoS level 31 and
It has a QoS table 16 and a QoS handler table 17.

The QoS level 31 is a numerical value defining a level when performing QoS control. QoS control task 11
Is the QoS level 31 according to the change of the system load.
Increase or decrease the value of.

The QoS table 16 is a table in which the required resource amount of each task is represented as a table corresponding to the QoS level 31. In the embodiment of the present invention, QoS
Since only the CPU time is handled as a resource in the control task, the QoS table 16 pre-records the CPU usage rate of each task, that is, the CPU usage time per unit time. FIG. 2 shows an example of the QoS table 16. As shown in FIG. 2, four tasks 0 to 3 are registered in the QoS table 16. For example, if the value of the QoS level 31 is 2, the task 0
The CPU utilization rates of “.about.3” are “0.4” and “0.
2 "," 0.0 ", and" 0.2 ".
As described above, the QoS control task 11 has the QoS level 31
The resource request amount of each task can be determined by referring to the QoS table 16 according to the value of.

The QoS handler table 17 shows the QoS handler of each task as a table for the task number. The QoS handler is actually the QoS
This function is called when performing control and is used to change the processing content of the application task. When the task (task number) to be subjected to the QoS control is determined, the QoS control task 11 can determine the QoS handler for the task by referring to the QoS handler table 17.

The idle time monitoring task 12
This is a task to check idle time. When the acquired idle time exceeds a predetermined value, the idle time monitoring task 12 wakes up the QoS control task 11. In kernels for workstations such as UNIX, a function to check the CPU utilization of the entire system is provided.
The idle time monitoring task can be easily realized. That is, the idle time can be monitored only by periodically checking the CPU utilization of the entire system.

However, a kernel in an embedded system generally has no means for checking the CPU utilization of the entire system. For this reason, in the QoS control device of the present invention,
The idle time monitoring task 12 is set as the task with the lowest priority, and a predetermined loop process is executed. That is,
By measuring the processing time (loop processing time) of the idle time monitoring task 12, the idle time of the CPU 1 can be checked. For example, when the processing time of the idle time monitoring task 12 is originally 10 ms, the measured processing time of the idle time monitoring task 12 is actually 10 ms.
If it is 0 ms, the idle time monitoring task 12 determines that it is using only 10% of the total CPU time of the system. That is, the idle time monitoring task 12
Can estimate that the idle CPU utilization at this time is 10%.

When detecting the deadline miss, the DL miss processing task 13 suspends the execution of the task in which the deadline miss has occurred, and wakes up the QoS control task 11. In addition, each application task 20-1 to 20
The -n deadline is set at each startup.

API (Application Programming Interface)
ace) 30 is an application task 20-1 to 20
-N is a set of system call interfaces (programs) for using the functions and the like of the OS 10, and Qo
S-table / QoS handler registration system call 14 is included.

The QoS table / QoS handler registration system call 14 is executed by the application tasks 20-1 to 20-1.
20-n QoS table entries 22-1 to 22-n
And the QoS handlers 21-1 to 21-n.

Application tasks 20-1 to 20-
n is an application program executed on the OS 10. Application tasks 20-1 to 20
-N is the corresponding QoS handler 21-1 to 21-2
1-n and QoS table entries 22-1 to 22-n
And

The QoS handlers 21-1 to 21-n are called when actually performing the QoS control, and are functions for changing the processing contents of the corresponding application tasks 20-1 to 20-n.

QoS table entries 22-1 to 22-
n is the corresponding application task 20-1 to 20
9 is a table showing the CPU utilization of −n as a table for the value of the QoS level 31. As described above, in the embodiment of the present invention, the QoS control task 11 handles only CPU time as a resource. for that reason,
The QoS table entries 22-1 to 22-n are stored in the CPU
The interrupt rate is calculated as “execution time / period” for tasks that are executed periodically, and “execution time × number of executions per second” for tasks that are executed periodically. In this case, it is represented by “execution time / shortest interrupt interval”.

Application tasks 20-1 to 20-
n is a task executed periodically, a task executed aperiodically, an interrupt handler, and the like. Although the interrupt handler is not strictly a task, it cannot be ignored in calculating the CPU utilization, and is therefore regarded as one of the application tasks. Also, it is assumed that the execution time and the like for the application tasks 20-1 to 20-n executed in the real-time system are obtained in advance. In other words, for a task that is executed periodically, the cycle, execution time, and deadline time are set. For a task that is executed aperiodically, the execution time and how many times the task is executed within a certain time are determined by an interrupt. As for the handler, it is assumed that the shortest interrupt interval and the execution time are determined in advance.

Application tasks 20-1 to 20-
The actual processing of n may vary. Nevertheless, the process related to the QoS control is performed by the application tasks 20-1 to 20-2.
0 to n are common. Therefore, the process related to the QoS control will be described below using the application task 20-1 as an example.

When the task is initialized, the application task 20-1 registers the QoS handler 21-1 and the QoS table entry 22-1 in the QoS control task 11. If the application task 20-1 is, for example, a moving image display task, the QoS handler 21-
As for 1, the value of the QoS level 31 is passed by an argument, and the frame rate and the resolution are changed. That is, when the value of the QoS level 31 is lower than before, the QoS handler 21-1 decreases the frame rate and the resolution to reduce the CPU utilization, while the value of the QoS level 31 is higher than before. In order to increase CPU utilization,
Increase frame rate and resolution. More specifically, taking the case of changing the frame rate as an example,
If the CPU utilization is 0.4 when the frame rate is 20 frames / sec, the CPU utilization is reduced to 0.2 or 0.2.
In order to reduce the number to 1, the QoS handler 21-1 changes the frame rate to 10 frames / second or 5 frames / second, respectively.

Hereinafter, the operation of the system incorporating the QoS control device according to the first embodiment of the present invention will be described in detail. As a premise, the QoS table entry 2 of the application tasks 20-1 to 20-n is assumed.
2-1 to 22-n and QoS handlers 21-1 to 21-21
-N needs to be registered in the QoS table 16 and the QoS handler table 17 before the execution of the task starts. First, the QoS table 16 and Q
The registration of the oS handler table 17 will be described.

This application task 20-1 to 20-2
A part of 0-n is generated by a task that has already been generated while the OS 10 is partially booted. That is, OS10
At the time of booting, an initial task (not shown) generates a QoS control task 11, an idle time monitoring task 12, and a DL miss processing task 13, and starts each task. Furthermore, the initial task is application task 2
0-1 to 20-n, for example, an application task 20-i (1 ≦ i ≦ n), and a QoS table entry 22-i and a QoS handler 21-i of the generated task are stored in the QoS table / The registration is performed using the QoS handler registration system call 14.

Also, for example, application task 2
When 0-j (1 ≦ j ≦ n) dynamically generates another application task 20-k (1 ≦ k ≦ n), the application task 20-j generates the application task 20-k of the generated application task 20-k. QoS table entry 22-k
And QoS handler 21-k in the QoS table / QoS
The registration is performed using the handler registration system call 14.

Next, the QoS control operation of the system incorporating the QoS control device according to the first embodiment of the present invention will be described with reference to the drawings. FIG. 3 is a flowchart illustrating a QoS control process performed by the QoS control task 11.

Normally, the QoS control task 11 is in a sleep state and waits for a QoS control request (step S1).
0). That is, the QoS control task 11 is woken up when a DL miss occurs due to a temporary overload state, or when there is enough CPU time.

The temporary overload state is when the task or handler exceeds the scheduled execution time. In this case, any one of the application tasks 20-1 to 20-n causes a DL miss. The DL miss processing task 13 detects the occurrence of a DL miss and notifies the QoS control task 11 that the DL miss is occurring. Also, C
If there is enough PU time, the task or handler may use less execution time than the scheduled execution time, or the task execution time may be reduced after the task execution time is reduced to eliminate the temporary overload condition. This is the case when the execution time of the task or handler that created the load state has decreased. In this case, when the idle time monitoring task 12 detects that the idle time has exceeded a predetermined value, the idle time monitoring task 12 notifies the QoS control task 11 that the free time of the CPU time has increased.

When the QoS control task 11 wakes up due to any of the above factors, it specifies the wake up factor (steps S11 and S21). That is, the QoS control task 11
First, it is determined whether a deadline miss has occurred (step S11).

The QoS control task 11 determines that a deadline miss has occurred (step S11; Ye).
s) It is determined whether or not the value of the QoS level 31 is the lowest value (step S12).

The QoS control task 11 performs QoS level 3
When it is determined that 1 is the lowest value (step S12; Y
es), the QoS control process ends. On the other hand, when it is determined that the QoS level 31 is not the lowest value (step S1).
2; No), the QoS control task 11 performs QoS level 3
The value of 1 is decreased by one (step S13).

After changing the value of the QoS level 31, the QoS control task 11 calls a QoS change process (step S14). The QoS change processing will be described later.

After the end of the QoS change processing, the QoS control task 11 determines whether or not there is a changed task (step S15).

If the QoS control task 11 determines that there is no changed task (step S15; No), the process returns to step S31. That is, the QoS control task 11 repeats the above steps S12 to S15 until a task that can change the CPU utilization is found and the CPU utilization of the entire system is reduced.

When the QoS control task 11 determines that there is a changed task (step S15; Yes),
The process ends. That is, the QoS control task 11
If it is determined in step S15 that there is a task whose CPU utilization has been changed, or if it is determined in step S12 that Q
When it is determined that the oS level 31 is the lowest value, the QoS
The control processing ends.

If it is determined in step S11 that no deadline miss has occurred (step S11).
11; No), the QoS control task 11 determines whether or not the load is low (step S21).

When the QoS control task 11 determines that the load is not low (step S21; No), the process ends without any special processing because it is a wake-up error (step S31). On the other hand, when it is determined that the load is low (step S21; Yes), it is determined whether or not the QoS level 31 is the highest value (step S22).

The QoS control task 11 performs QoS level 3
1 is determined to be the highest value (step S22; Y
es), the QoS control process ends. On the other hand, when it is determined that the QoS level 31 is not the highest value (step S2).
2; No), the QoS control task 11 performs QoS level 3
The value of 1 is increased by one (step S23).

After changing the value of the QoS level 31, the QoS control task 11 calls a QoS change process (step S24). The QoS change processing will be described later.

After the end of the QoS change processing, the QoS control task 11 determines whether or not there is a changed task (step S25).

If the QoS control task 11 determines that there is no changed task (step S25; No), the process returns to step S22. That is, the QoS control task 11 repeats the above steps S22 to S25 until a task that can change the CPU utilization is found and the CPU utilization of the entire system is increased.

If the QoS control task 11 determines that there is a changed task (step S25; Yes),
The QoS control processing ends. That is, the QoS control task 11 determines in step S25 that there is a task whose CPU utilization has been changed, or in step S2.
If it is determined in step 2 that the QoS level 31 is at the maximum value, the QoS control process ends.

Next, step 14 and step S2
4 will be described with reference to FIG. FIG. 4 is a flowchart illustrating a QoS change process performed by the QoS control task 11.

The QoS control task 11 selects one of the tasks T registered in the QoS table 16 (Step S41).

The QoS control task 11 compares the value of the QoS table 16 corresponding to the value of the QoS level 31 before the change with respect to the task T with the value of the QoS table 16 corresponding to the value of the QoS level 31 after the change ( Step S4
2).

The QoS control task 11 checks the QoS before and after the change.
The value of the QoS table 16 corresponding to the value of the S level 31;
That is, it is determined whether the CPU utilization is different (step S43).

If the QoS control task 11 determines that the CPU utilization is different (step S43; Yes), it calls the QoS handler of the task T with the changed QoS level 31 value as an argument (step S44).

The QoS control task 11 determines whether all the tasks have been checked (step S45).

If the QoS control task 11 determines that all tasks have not been checked (step S45; N
o), the process returns to step S41. That is, QoS
The control task 11 repeats the above steps S41 to S45 for all the tasks registered in the QoS table 16, and sets the QoS level 31 before and after the change.
Of the CPU utilization rate corresponding to the value of the task T, and when there is a difference in the CPU utilization rate, the QoS handler of the task T is called with the changed QoS level 31 value as an argument.

When all the tasks have been checked (step S45; Yes), the QoS control task 11
It returns to the caller whether or not there is a task whose U usage rate has been changed (step S46), and the QoS change processing ends.

Next, the QoS control operation of the present embodiment will be specifically described with reference to the QoS table 16 shown in FIG. As shown in FIG. 2, the current QoS table 16 includes four of task 0, task 1, task 2, and task 3.
One task is registered. It is also assumed that the current value of the QoS level 31 is “6”.

In this state, if any application task causes a DL miss, the QoS control task 1
1 wakes up and determines that a deadline mistake has occurred (step S11; Yes). QoS control task 11
Determines that the QoS level 31 is "6" and is not the lowest value (step S12; No), and lowers the value of the QoS level 31 by one to "5" (step S13).

In the QoS change processing, the CP of task 0
Only U utilization rate, QoS level 31 from "6" to "5"
Is determined to change from "0.5" to "0.4" (step S43; Yes).
"5" of QoS level 31 after changing the QoS handler of
Is called with an argument (step S44).

As a result, the CPU utilization of the entire system is set to 0.1, that is, 1 from the time when the DL miss occurred.
It can be expected to drop by 0%.

Further, if a DL miss still occurs, the QoS control task 11 determines that the QoS level 31 is “5” and is not the lowest value (step S1).
2; No), the value of the QoS level 31 is reduced by one to “4” (step S13). In the QoS change processing, only the CPU utilization of the task 1 is set, and the QoS level 31 is set to “5”.
Is changed from “0.3” to “0.
2 "(step S43; Ye).
s), calling the QoS handler of task 1 with the changed QoS level 31 “4” as an argument (step S4)
4).

As a result, it can be expected that the CPU utilization of the entire system is further reduced by 0.1, that is, 10%.

As described above, the value of the QoS level 31 is D
It is lowered until no L-miss occurs or becomes zero. For example, assuming that when the CPU utilization of the entire system exceeds 1, an overload occurs and a deadline miss occurs, the QoS level 31 is reduced to "3" at which the CPU utilization of the entire system becomes 0.9. .

On the other hand, if the idle time monitoring task 12 notifies that the load is low when the QoS level 31 is “3”, the QoS control task 11 wakes up and determines that the load is low. (Step S21; Y
es). The QoS control task 11 determines that the QoS level 31 is “3” and is not the highest value (step S2).
2; No), the value of the QoS level 31 is increased by one to “4” (step S23).

In the QoS change process, the CP of task 3
Only U utilization rate, QoS level 31 is "3" to "4"
Is determined to change from "0.2" to "0.4" (step S43; Yes).
"4" of QoS level 31 after changing the QoS handler of
Is called with an argument (step S44).

As a result, the CPU utilization of the entire system is set to be lower than that at the time when the low load state is notified.
2, that is, it can be expected to increase by 20%.

As described above, in the QoS control apparatus according to the first embodiment of the present invention, the QoS control task 11 performs resource allocation of each task only by referring to the QoS table 16. Therefore, resource allocation for each task can be determined without necessity of negotiation for resource allocation with the task. As a result, QoS control can be performed at high speed. Also, by appropriately setting the amount of resource required to be set in the QoS table 16 at the time of designing the embedded system, resource allocation to each task and QoS change are performed based on the QoS table 16. As a result, QoS control can be performed as intended by the designer.

Next, a QoS control apparatus according to a second embodiment of the present invention, which manages a case where a task becomes valid and a case where a task becomes invalid, will be described with reference to the drawings. explain. FIG. 5 is a block diagram illustrating an example of a configuration of a system incorporating the QoS control device according to the second embodiment of the present invention.

The system incorporating the QoS control device shown in FIG. 5 has the QoS according to the first embodiment shown in FIG.
System with built-in control device and QoS control task 4
Only 1 and API 40 are different. That is, other configurations are the same as those in FIG.

The QoS control task 41 has a new effective task table 18 in addition to the configuration of the QoS control task 11 shown in FIG.

The valid task table 18 is a list of tasks and handlers to be used when calculating the CPU utilization of the entire system. More specifically, in the valid task table 18, everything that constantly consumes CPU time is registered. Then, when the state changes to a sleep state, an I / O wait state, or the like, and the CPU time is not constantly consumed, the CPU is removed from the valid task table 18. That is, the effective task table 18 allows the CPU utilization of the entire system to be calculated appropriately. Note that the CPU utilization of the entire system is obtained by acquiring the target CPU utilization from the QoS table 16 for tasks and interrupt handlers included in the valid task table 18 and summing them.

The API 40 has a new valid task registration / deletion system call 15 in addition to the API 30 shown in FIG.

Valid task registration / deletion system call 15
Indicates that the application tasks 20-1 to 20-n are activated and change to a state in which the CPU time is steadily used.
Judgment of a change to a state in which CPU time is not constantly used due to waiting for / O, etc., and enabling / disabling a task by QoS.
Notify the control task 41. Specifically, when the application tasks 20-1 to 20-n themselves start a task, wake up the task, or enter an I / O wait state, or enter a sleep state, the valid task registration / The delete system call 15 is called to notify the QoS control task 41 of the activation / inactivation of the task.

Next, the QoS control operation of the system incorporating the QoS control device according to the second embodiment of the present invention will be described with reference to the drawings. FIG. 6 is a flowchart illustrating a QoS control process performed by the QoS control task 11.

Normally, the QoS control task 11 is in a sleep state and waits for a QoS control request (step S5).
0). That is, the QoS control task 11 is activated when a task such as a case where a new one of the application tasks 20-1 to 20-n is started or a task in a sleep state is woken up. Alternatively, it is woken up when the task becomes invalid, such as when the task is completed or when the flag is waiting to be established. A normal system call is issued to start or pause the task, but each task performs the task validation / invalidation using the valid task registration / deletion system call 15 prior to this. . However, a task that is periodically executed periodically repeats sleep and wake-up, but periodically requires CPU time. Therefore, the task is not enabled / disabled each time it wakes up or sleeps.

When the QoS control task 11 wakes up due to any of the above factors, it specifies the wake up factor (steps S51 and S61). That is, the QoS control task 11
First, it is determined whether a valid task has been added (step S51).

When the QoS control task 11 determines that an effective task has been added (step S51; Yes),
The task is added to the valid task table 18 and registered (step S52).

The QoS control task 11 calls a utilization calculation process for calculating the CPU utilization of the entire system (step S53). The utilization rate calculation processing will be described later.

After the utilization rate calculation processing is completed, the QoS control task 11 determines the CP of the entire system obtained in the utilization rate calculation processing.
It is determined whether the U utilization rate U is larger than a predetermined maximum value Umax (step S54).

The QoS control task 11 has a CPU utilization U
Is smaller than or equal to the maximum value Umax (Step S54; No), the process proceeds to Step S67 described later.

On the other hand, when it is determined that the CPU utilization U is larger than the maximum value Umax (step S54; Yes),
The QoS control task 11 determines whether or not the value of the QoS level 31 is the lowest value (Step S55). That is, when the CPU utilization U is larger than the maximum value Umax, the QoS control task 11 regards the system as being in an overloaded state, and determines whether or not the QoS level 31 can be reduced to eliminate the overloaded state. Is determined.

[0107] The QoS control task 11 performs QoS level 3
When it is determined that 1 is the lowest value (step S55; Y
es), the process proceeds to step S57 described below. When it is determined that the QoS level 31 is not the lowest value (step S55; No), the QoS control task 11
The value of the QoS level 31 is reduced by one (step S5).
6).

After changing the value of the QoS level 31, the QoS control task 11 returns the processing to step S53.
That is, the QoS control task 11 obtains the CPU utilization rate of the entire system at the time of adding the valid task, and when the system is overloaded, repeats the above-described steps S53 to S56 to change the value of the QoS level 31. Lower sequentially.

When the CPU utilization U becomes equal to or less than the maximum value Umax, the QoS control task 11 advances the processing to step S67, which will be described later, and calls the QoS change processing. On the other hand, if the value of the QoS level 31 becomes the lowest value in step S56 before the CPU utilization U does not become equal to or less than the maximum value Umax, the QoS control task 11 returns the value of the QoS level 31 to the original value. Then, the added task is deleted from the valid task table 18, and an error indicating that the task addition has failed is returned to the task (step S57).

When it is determined in step S51 that no valid task has been added (step S5).
1; No), the QoS control task 11 determines whether or not the valid task has been deleted (step S61).

When the QoS control task 11 determines that the valid task has not been deleted (step S61; N
o), the process proceeds to step S11 in FIG. 3 of the second embodiment. In addition, the process after step S11 of FIG.
The description is omitted because it is the same as the first embodiment.

When the QoS control task 11 determines that the valid task has been deleted (step S61; Yes),
The task is deleted from the valid task table 18 (step S62).

The QoS control task 11 performs QoS level 3
It is determined whether 1 is the highest value (step S6).
3). When the QoS control task 11 determines that the QoS level 31 is the highest value (step S63; Ye)
s) The process proceeds to step S67 described below.

On the other hand, if the QoS control task 11 determines that the QoS level 31 is not the highest value (step S63; No), the QoS control task 11 calls a utilization calculation process for calculating the CPU utilization of the entire system (step S64). The utilization rate calculation processing will be described later.

The QoS control task 11 determines whether or not the CPU utilization rate U of the entire system obtained in the utilization rate calculation processing is equal to or less than a predetermined minimum value Umin (step S65).

The QoS control task 11 has a CPU utilization U
Is larger than the minimum value Umin (Step S65; No), the process proceeds to Step S67 described later. On the other hand, when determining that the CPU utilization U is equal to or smaller than the minimum value Umin (Step S65; Yes), the QoS control task 11 increases the value of the QoS level 31 by one (Step S66).

After changing the value of the QoS level 31, the QoS control task 11 returns the processing to the step S63.
That is, the QoS control task 11 performs the QoS level 31
Until the value of becomes the maximum value or the CPU utilization of the entire system becomes larger than the minimum value Umin.
63 to step S66 are repeated to increase the value of the QoS level 31.

If the value of the QoS level 31 reaches the maximum value in step S63, or if the CPU utilization of the entire system exceeds the minimum value Umin in step S65, Q
Call the oS change process (step S67). That is, the QoS control task 11 performs the same QoS change processing as in FIG. 4 described in the first embodiment, and executes the QoS handler of the task having a different CPU utilization.

Next, steps S53 and S64
Will be described with reference to FIG. FIG. 7 is a flowchart illustrating a utilization rate calculation process performed by the QoS control task 11.

First, the QoS control task 11 sets an initial value “0” to the CPU utilization U (step S71).

The QoS control task 11 selects one of the tasks T registered in the valid task table 18 (Step S72).

The QoS control task 11 sets the CPU utilization of the task T corresponding to the current value of the QoS level 31 to the QoS level.
C from the S table 16
It is added to the PU utilization rate U (step S73).

The QoS control task 11 determines whether or not the CPU utilizations of all tasks have been added (step S74). If the QoS control task 11 determines that the CPU utilizations of all tasks have not been added (step S74; No), the process returns to step S72. That is, the QoS control task 11 stores the effective task table 1
Steps S72 to S74 are repeated for all the tasks registered in No. 8, and the CPU utilization U of the entire system is obtained.

When the CPU utilizations of all the tasks are added (step S74; Yes), the QoS control task 1
1 returns the CPU utilization U to the caller, and ends the utilization calculation processing.

According to the second embodiment of the present invention, when a task is in a state of constantly consuming CPU time and in a state of not consuming CPU time, the task is changed by the CPU utilization rate of the task. Change the QoS level. As a result, even when the CPU utilization time of the entire system greatly changes due to sleep or waking up of a task, the desired C can be promptly changed.
Can be adjusted to PU utilization. In addition, since the QoS change target task is determined by referring to the valid task table, although the QoS table is registered,
No QoS change processing or the like is performed for a task in the sleep state. Therefore, useless processing is not performed, and Q
The oS control process becomes faster.

Next, the QoS control operation of the present embodiment will be specifically described with reference to the QoS table 16 shown in FIG. It is assumed that three tasks of task 0, task 1, and task 2 except for task 3 in FIG. 2 are registered in the QoS table 16 first. Also,
The value of the current QoS level 31 is “6”. Also,
The maximum value Umax of the CPU utilization of the entire system is “1.
0 "and the minimum value Umin is" 0.9 ".

In this state, if the new task 3 becomes executable, the QoS control task 11 wakes up and determines that an effective task has been added (step S51; Ye).
s).

The QoS control task 11 adds the task 3 to the valid task table 18 (step S52), and calculates the CPU utilization U of the entire system (step S5).
3). That is, the QoS control task 11 has the CPU utilization of each task of “0.5”, “0.3”, “0.1”, and “0.4” with respect to QoS level 31 “6”. Therefore, the CPU utilization rate U of the entire system
Is calculated as “1.3”.

The QoS control task 11 determines that the obtained CPU utilization U is larger than the maximum value Umax (step S54), and lowers the value of the QoS level 31 from “6” to “5” (step S56).

The QoS control task 11 performs QoS level 3
Even if the value of 1 is changed to "5", it is determined that the CPU utilization U again obtained in step S53 is larger than the maximum value Umax, and the value of the QoS level 31 is sequentially reduced, and the CPU utilization U
Is calculated (steps S53 to S56).

The QoS control task 11 performs QoS level 3
When the value of 1 is changed to “3”, the CPU utilization U obtained in step S53 becomes “0.9”, and the maximum value Uma
x or less (step S54; No).

The QoS control task 11 sets the QoS level to “3” and sets the QoS level of the task 0,
A QoS handler is executed for task 1 and task 3 (step S67).

As a result, when a task that constantly consumes CPU time is added, control can be performed so that the overall CPU utilization does not exceed the maximum value.

On the other hand, when the QoS level 31 is “3” and the task 0, the task 1, the task 2, and the task 3 are being executed, the task 1 enters a sleep state and is invalidated. The control task 11 wakes up and determines that the valid task has been deleted (step S61; Ye).
s).

The QoS control task 11 deletes the task 1 from the valid task table 18 (step S62), and calculates the CPU utilization U of the entire system (step S6).
4). That is, in the QoS control task 11, the CPU utilization of each task excluding the task 1 with respect to “3” of the QoS level 31 is “0.4”, “0.1”, and “0.2”. Therefore, the CPU utilization rate U of the entire system
Is calculated as “0.7”.

The QoS control task 11 determines that the obtained CPU utilization U is equal to or less than the minimum value Umin (step S65), and raises the value of the QoS level 31 from “3” to “4” (step S66).

The QoS control task 11 performs QoS level 3
Even if the value of 1 is changed to "4", it is determined that the CPU utilization U again obtained in step S64 is equal to or less than the minimum value Umin, and the value of the QoS level 31 is sequentially increased, and the CPU utilization U
Is calculated (steps S63 to S66).

The QoS control task 11 performs QoS level 3
When the value of 1 is changed to “6”, it is determined to be the highest value of the QoS level 31 (Step S63; Yes).

[0139] The QoS control task 11 sets the QoS level to "6",
Then, a QoS handler is executed for task 3 (step S67).

In the first and second embodiments, Q
Qo indicates the task resource requirement for the value of oS level 31
Although it is determined using the S table 16 or the like, the resource requirement of the task may be determined using a QoS function instead of the table. Hereinafter, a description will be given of a modification according to the embodiment of the present invention, which is characterized in that the required resource amount of a task is obtained using a QoS function.

In this modification, for example, QoS level 3
A QoS function that takes a value of 1 as an argument and returns a resource request amount of each task corresponding to the argument is used. Also, the QoS table / QoS handler registration system call 14 uses a QoS function instead of a QoS table entry as an argument.

More specifically, for example, the QoS control task 11 obtains the CPU utilization rate of each task for the QoS level 31 during the utilization rate calculation processing of FIG. 7 (step S73) and the QoS control task of FIG. During the change process, when the CPU utilization of each task for the QoS level 31 before and after the change is obtained (step S42), the QoS function is called to determine the resource request amount of the application task.

In this modification, unlike the first and second embodiments using a QoS table or the like, as the number of QoS levels increases, the size of the QoS table entry increases, consuming a large amount of memory. The problem of getting lost is eliminated. That is, in this modification, the same amount of memory can always be used irrespective of the level of the QoS level. In particular, when the resource demand of the task is expressed as a simple function, the first and the second are used. The memory usage can be significantly reduced as compared with the second embodiment.

As described above, when the QoS control device according to the second embodiment of the present invention regularly consumes CPU time due to waking up of a task or the like, the CPU utilization of the task is reduced. The QoS level is reduced so that the CPU utilization of the entire system does not exceed the maximum value even if the minutes are added. Further, when CPU time is not consumed due to sleep of a task or the like, the QoS level is raised so that the CPU utilization of the entire system does not exceed the minimum value even if the CPU utilization of the task is reduced. As a result, if the CPU utilization of the entire system changes significantly due to the wake-up or sleep of the task, the CPU of the entire system is changed.
The utilization can be quickly adjusted to an appropriate value.

The broadcast system of the present invention can be realized by using a general computer system without using a dedicated system. For example, a QoS control device that executes the above-described processing is installed in a computer by installing the program from a medium (floppy (registered trademark) disk, CD-ROM, or the like) storing the program for executing any of the above. Can be configured.

The medium for supplying the program to the computer may be a communication medium (medium for temporarily and fluidly holding the program, such as a communication line, a communication network, or a communication system). For example, the program may be posted on a bulletin board (BBS) of a communication network and distributed via the network. Then, by starting this program and executing it in the same manner as other application programs under the control of the OS, the above-described processing can be executed.

[0147]

As described above, according to the present invention,
In an embedded real-time system, QoS control can be performed at high speed.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating an example of a configuration of a system incorporating a QoS control device according to a first embodiment of the present invention.

FIG. 2 is a schematic diagram illustrating an example of a QoS table.

FIG. 3 is a flowchart illustrating a QoS control process according to the first embodiment of the present invention.

FIG. 4 is a flowchart illustrating a QoS change process according to the first embodiment of the present invention.

FIG. 5 is a block diagram illustrating an example of a configuration of a system incorporating a QoS control device according to a second embodiment of the present invention.

FIG. 6 is a flowchart illustrating a QoS control process according to a second embodiment of the present invention.

FIG. 7 is a flowchart illustrating a utilization rate calculation process for determining a CPU utilization rate of the entire system according to the second embodiment of the present invention;

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 CPU 2 Memory 3 ROM 10 OS 11 QoS control task 12 Idle time monitoring task 13 DL miss processing task 14 QoS table / QoS handler registration system call 15 Effective task registration / deletion system call 16 QoS table 17 QoS handler table 18 Effective task table 19 Real-time kernel 20-1 (20-n) Application task 21-1 (21-n) QoS handler 22-1 (22-n) QoS table entry 30 API 31 QoS level 40 API 41 QoS control task

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-2000-155563 (JP, A) JP-A-11-66018 (JP, A) JP-A-60-238938 (JP, A) Tatsuo Nakajima, “Dynamic QOS Control and Resource Reservation, "IEICE Technical Report, Vol. 569 (CPSY97-112 to 122), The Institute of Electronics, Information and Communication Engineers, published (February 25, 1998), pp. 25-32 (58) Fields investigated (Int. Cl. ⁷ , DB name) G06F 9/46 G06F 15/16 G06F 15/00 G06F 1/00 JICST file (JOIS) CSDB (Japan Patent Office)

Claims (2)

(57) [Claims] 1. Managing resources in a computer system
Service for tasks started under OS control
QoS control device that controls the quality of service (QoS)
Te, corresponding to each class in the class of QoS that a predetermined
Allocation storage means for storing the allocation of resources for each task to be performed
And a report showing the current grade of QoS in the computer system.
A level value storage means for storing a bell values determined from the stored level value in the level value storage unit
According to the resource quota stored in the quota storage means
From the computer system where each task is running,
A utilization rate obtaining means for obtaining the utilization rate of resources utilization of resources acquired by the usage rate obtaining means pre
The level value is stored so that it falls within a predetermined range.
Change the level value stored in the means, and change the changed level value
From the quota stored in the quota storage means determined from
QoS control means for changing the QoS for a task
And at least start up and wake up in the computer system
Manages effective tasks that regularly use the resources of
And a valid task management means for management, the utilization rate acquisition means, managed by the enable task manager
In the computer system for a valid task
And the QoS control unit acquires the utilization rate of the resource by the utilization rate acquiring unit.
Resource utilization exceeds the predetermined maximum
In this case, at least the
To reduce the amount of resources allocated to one task,
Changing the level value stored in the level value storage means,
A QoS controller for changing a QoS for a corresponding task . 2. Managing resources in a computer system.
Service for tasks started under OS control
QoS control device that controls the quality of service (QoS)
Te, corresponding to each class in the class of QoS that a predetermined
Quota storage means for storing the quota of resources for each task; and a report indicating the current grade of QoS in the computer system.
A level value storage means for storing a bell values determined from the stored level value in the level value storage unit
According to the resource quota stored in the quota storage means
From the computer system where each task is running,
A utilization rate obtaining means for obtaining the utilization rate of resources utilization of resources acquired by the usage rate obtaining means pre
The level value is stored so that it falls within a predetermined range.
Change the level value stored in the means, and change the changed level value
From the quota stored in the quota storage means determined from
QoS control means for changing the QoS for a task
And the computer system at least terminates and waits for processing.
Manage invalid tasks that do not regularly use resources in the system.
And a disable task management means for management, the utilization rate acquisition means, managed by the disable task manager
In the computer system, except for invalid tasks
And the QoS control unit acquires the utilization rate of the resource by the utilization rate acquiring unit.
Resource utilization exceeds the predetermined minimum
If not, at least the amount stored in the quota storage means
Also increase the amount of resources allocated to one task
Changes the level value stored in the level value storage means.
And changing the QoS for the corresponding task .