JPH10283204A - Multi-task processing method, multi-task processor and recording medium recording task - Google Patents

Abstract

PROBLEM TO BE SOLVED: To satisfy the request for the task of a high priority level requesting a real time property by putting sleep in the task of a low priority level and/or shortening the time of one time for accessing a common device. SOLUTION: By putting the sleep into the task of the low priority level among the plural tasks for using the common device (hard disks 22) and/or shortening the time for accessing the device, the request (real time property) is satisfied for the task of the high priority level. Especially, at the time of a first task for storing image data read in an image reader 10 in a storage means (hard disk 22) and a second task for reading the image data stored in the storage means, by defining the first task as the task of the high priority level and putting the sleep into the second task and/or shortening the time for accessing the storage means, the capacity of a first memory 12 is reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multitask processing method and apparatus for switching a plurality of tasks at predetermined time intervals and processing each task, and a recording medium recording the tasks. In particular, the present invention relates to a method, an apparatus, and a recording medium on which tasks are multi-task processed for a plurality of tasks accessing a common device.

[0002]

2. Description of the Related Art At present, processing devices such as computers are:
It supports multitask processing. This multi-task processing means that the central processing unit (CPU), which is the center of the processing unit, can execute only one process at a time.
To give each of a plurality of tasks time to occupy the CPU and apparently process the plurality of tasks on one processing device. Among them, there is a multitask in which an OS (operating system) manages a plurality of tasks, switches the plurality of tasks at predetermined time intervals, and processes each task (multitask referred to in this specification).

Referring to FIG. 5A schematically showing this multitask processing, when processing the first task and the second task by the multitask, a predetermined time (here, , About 0.1 seconds), the processing of the first task, the processing of the second task, the processing of the first task,...
Each task occupies the CPU for processing. By doing so, it looks as if the first task and the second task are processed simultaneously and in parallel.

[0004]

In the multitask processing described above, if the device accessed by the first task is the same as the device accessed by the second task,
For example, a problem occurs when the first task is a task of writing information to a hard disk incorporated in the processing device and the second task is a task of reading information stored in the hard disk. In particular, this is remarkable when one of the tasks is a task that requires real-time properties.

[0005] This will be described with reference to FIG. Here, it is assumed that the first task requires a real-time property (that is, a task having a high priority level). First, the first task is processed for about 0.1 second, and then the second task is processed. In this case, if the second task is a task for reading a large amount of data, the CPU is not occupied so much, but it takes about one second to read a device shared with the first task (a hard disk that is a common device) ( (A chain line in the figure). Then, even if about 0.1 second has elapsed after the processing of the second task has started and the occupation of the CPU has shifted to the first task, if the first task at this time is writing to the hard disk, Since reading is performed based on the second task, writing based on the first task cannot be performed. Therefore, the first
The task will wait until about one second after the completion of the reading based on the second task. That is, in this case, as shown in FIG. 5C, the second task is a first task that requires real-time property but does not require real-time property than the first task (ie, has a lower priority level).
Since a common device is being accessed based on the task, it has to wait for one second, and the required real-time property cannot be achieved.

In addition, priority control (priority control) is performed so that task priority control is given as a multitask, that is, important tasks are given more CPU occupation time. Even if given, this method is practically useless because a common device cannot be used.

[0007] Therefore, an object of the present invention is to provide a multitask process capable of satisfying a task that requires real-time properties.

[0008]

The above object can be achieved by the following constitution.

(1) In a multitask processing method for processing a plurality of tasks by switching the plurality of tasks at predetermined time intervals, when each of the plurality of tasks is a task that accesses a common device, A multitask processing method, wherein a sleep is placed in a task having a lower priority level among tasks, and a non-sleep task is processed when the task in which the sleep is put is sleeping.

(2) In a multitask processing method for processing a plurality of tasks by switching the plurality of tasks at predetermined time intervals, when each of the plurality of tasks is a task that accesses a common device, A multi-task processing method, wherein one task of a task having a lower priority level among tasks accesses one common device at a time.

(3) When the task having a lower priority level among the plurality of tasks is a task for reading out image information stored in the storage means or causing the storage means to store the image information, the task stored in the storage means is stored. The multi-task processing method according to (2), wherein the read image information or the entire data of the image information to be stored in the storage means is read out or stored in a plurality of times.

(4) A sleep is placed in the task with the lower priority level, and when the task in which the sleep is put is in a sleep state, a task that is not in a sleep state is processed (2) or (3). ).

(5) When the task with the lower priority level among the plurality of tasks is the second task for reading out the image information stored in the storage means or storing the image information in the storage means, The multitask processing method according to (4), wherein the task puts a sleep every time the task is read from the storage means or stored in the storage means.

(6) In the sleep, the time is changed according to a priority level (1).
(4) The multitask processing method according to any one of (5).

(7) The task having a higher priority level among the plurality of tasks is a first task for storing the image information read by the image reading device in the storage means, and the task having a lower priority level among the plurality of tasks. The multitask according to any one of (1) to (6), wherein the task is a second task for reading out the image information stored in the storage unit or storing the image information in the storage unit. Task processing method.

(8) In a multitask processing apparatus for processing a plurality of tasks by switching the plurality of tasks at predetermined time intervals, the plurality of tasks store image information read by an image reading device in a storage unit. Tasks and
When the second task is to read out the image information stored in the storage means or to store the image information in the storage means, the second task is caused to change the amount of data read out once from the storage means. Means for setting all data of the image information read from the storage means to be read in a plurality of times; and for the second task, only once or a plurality of times of reading from the storage means for a predetermined time. Means for setting to sleep, wherein when the task to be processed is sleeping, the non-sleeping task is processed.

(9) A multi-task process in which a plurality of tasks are switched at predetermined time intervals to process each task, and a task for accessing a device common to other tasks is recorded on a recording medium. One time to access the common device and / or a time to sleep after the access is determined according to the priority level, and the common device is accessed and / or accessed according to the determined time. A recording medium on which a task characterized by sleeping later is recorded.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic configuration diagram of hardware.

The image reading device 10 is a device that converts an image into an electric signal by photoelectric conversion or the like and reads image information, and for example, a scanner, a reader, a radiation image reading device, or the like is used. The image reading apparatus 10 can make various changes, such as a sampling pitch, a width, a height, and an information amount (bit number) per pixel, for reading an image.
The configuration is such that the amount of read data per unit time read by the image reading device can be variously changed.

A controller 11, which is a reading control unit, is a means for controlling the image reading device 10, and controls the image reading device 1.
The sampling pitch, width, height,
Various changes such as the information amount (bit number) per pixel, that is, the amount of read data per unit time read by the image reading device are set, and the image reading device 10 is set based on this setting.
Control. The controller 11 is provided with a first memory 12 as a first storage means. The first memory 12 is a means for temporarily storing image information read by the image reading device 10, and as image data in the order in which the images read by the image reading device 10 are read (after image processing such as shading correction is performed). Store sequentially. The image reading unit 10 may be controlled by the controller 11 itself, but may be controlled by the computer 20 via the controller 11 according to an instruction from the computer 20 as described later.

The computer 20 is a workstation or a personal computer, and sends and receives data to and from various devices connected to the computer 20 based on a predetermined program (task) and controls the various devices. Means. This computer 2
0 incorporates various interfaces, such as a SCSI board 21, an Ethernet board 23, and a graphic board 24, in order to transfer and control data.
Further, the computer 20 is provided with a main memory 26 for temporarily storing data when data is exchanged between various devices. Each component in the computer 20 includes a CPU 26 serving as a central processing unit. Is controlled by a predetermined task.

The SCSI board 21 has the above-described controller 11 via a bus, a hard disk 22 as a storage means built in the computer 20 (may be externally attached), and an MO (magneto-optical disk) device 33 as an external storage means. Etc. are connected. As described above, the controller 11 has the first memory 12, which is a unit for controlling the image reading device 10, and stores the image data read by the image reading device 10 sequentially. Also,
The hard disk 22 and the MO device 33 are means for storing various programs (tasks) and data such as image data. These controller 11 and hard disk 2
2. The MO device 33 exchanges (transfers) data via the SCSI board 21 at a transfer rate of, for example, 10 MB / s.

Further, the computer 20 is provided with an Ethe
The network (for example, L
AN), and a host computer 30, a printer 32, and the like. The host computer 30 is means for storing image data and the like.
The printer 32 is means for printing out image data and the like. The graphic board 24 is connected to a CRT 31 which is a display unit for displaying image data read by the image reading unit 10 and the like.

The computer 20 processes a plurality of tasks using an OS (operating system) that supports multitask processing, and controls various devices based on the tasks. As multitask processing, the OS manages a plurality of tasks, switches the plurality of tasks at predetermined time intervals, and processes each task. When a task is in a sleep state (temporarily suspends execution of a process), the OS skips that task and processes the next task.

Next, various tasks will be described.
In the following description, the task of storing the image data (stored in the first memory 12) read by the image reading device 10 in the hard disk 22 and the image data (read by the image reading device 10) stored in the hard disk 22 Two tasks for outputting the output image data) to an output device (the printer 32, the MO device 33, the host 30, etc.) will be described.

First, the task of storing image data read by the image reading device 10 in the read hard disk 22 will be described with reference to FIG. 2 which is a flowchart. In the example of FIG. 2, the image data read by the image reading device 10 and sequentially stored in the first memory 12 is read and stored in the hard disk 22 (that is, the image data read by the image reading device is stored in the first memory 12). Is transferred to the hard disk 22) and displayed on the CRT 31.

First, when an image is read by the image reading device 10, the sampling pitch and width of the image reading by the image reading device 10 are read by external input means such as a keyboard for inputting information from outside the computer 20 (not shown) prior to reading. Then, read information such as the height, the amount of information per pixel (the number of bits), and the like (the amount of read data per unit time read by the image reading device) is set (S1).
The computer 20 sets the amount of read data at one time (which is the same as the amount of transfer data) according to the read information (S2). This setting depends on the sampling pitch,
The width, height, and the larger the amount of information per pixel (ie, the larger the amount of read data per unit time), the larger the amount of read data per operation, and the smaller the amount of read data per unit time, the more It is set so that the amount of read data per time is reduced. On the other hand, the set read information is stored in the SCSI board 2
1, the controller 11 controls the image reading apparatus 10 based on the read information, and starts reading an image.

When the image reading is started, the image data read by the image reading apparatus 10 based on the set read data amount is sequentially stored in one memory 1 in the reading order.
2 is stored. The image data stored in the first memory 12 is read based on the one-time read data amount set in S2 (S3). That is, although the entire image data of one image read by the image reading device 10 is several tens MB (megabytes), the entire image data is temporarily stored in the first memory 12, and then the image data is read from the first memory 12. Instead of reading out the image
The image data sequentially stored in the first memory 12 in the order in which they were read is read out as a block of data of several hundred KB to several tens KB (set in S2 according to the read information), and this is repeated a plurality of times. Read all the image data of one sheet.

The read image data for one read data amount is temporarily stored in the main memory 25, and then stored in the SC.
Writing is performed on the hard disk 22 via the SI board 21 (S4). The image data stored in the main memory 25 is stored in the hard disk 22 and stored in the CRT 3.
1 to perform image processing for display on the CRT 31 (S5), and display the image on the CRT 31.

If all the image data of the image read by the image reading device 10 has not been read (S7), the process returns to S3. That is, the image data sequentially stored in the first memory 12 in the order of being read by the image reading device 10 is read from several hundred KB to several tens KB (in S2, according to the read information, until all the image data of one sheet is read). (Set) is read out as a block of data, and this is repeated a plurality of times. When all reading is completed, all image data stored in the main memory 25 (specifically, S
In step 5, the thinned image data) is subjected to image processing (S8) by obtaining the parameters of gradation processing for contrast adjustment, converted into a contrast, and displayed again on the CRT 31 (S9).

According to this task, when the image data read by the controller 11 and stored in the first memory 12 is read from the first memory 12, the image reading device 1
0 corresponds to the read data amount per unit time to be read,
The amount of read data to be read from the first memory 12 is set (S
2) Since the image data is read from the first memory 12 based on the read data amount, the read data amount does not become insufficient or excessive with respect to the read data amount read by the image reading device 10, and the read data amount does not occur. There is no need to wait for reading until the amount is equal.
Does not need to be a large-capacity memory, and there is no need to take measures such as interrupting reading by the image reading device 10.

Next, the image data stored in the hard disk 22 is output to an output device (the printer 32 or the MO device 33).
And the task output to the host 30) will be described with reference to FIG. 3 which is a flowchart. This task has a lower priority (priority level) than the task of storing the image data read by the image reading device 10 on the read hard disk 22, that is, a task that does not require real-time performance than the above-described task. . This is because the image data read by the image reading device 10 is sequentially stored in the first memory 12 in the reading order, so that the time stored in the first memory 12 is shortened, and the first memory 12 This is because it is necessary to increase the priority (priority level) of the above-mentioned task in order to reduce the capacity. In particular, the medical image reading apparatus 10
When an X-ray image reading device or the like is used, the above-described task needs to be performed in real time in order to make the imaging time of the patient more efficient or to quickly end the imaging by the patient. Such a task is stored in the information recording medium and processed by the computer 20.

First, when outputting an image to an output device,
Prior to output, output information such as designation of image data (image ID) to be output as an image, width and height is set by an external input means such as a keyboard for inputting information from outside the computer 20 (not shown) (S11). Next, the task being processed by the computer 20 is checked, and if another task is being processed by the computer 20, the priority level (priority, real-time property) between the other task and this task is determined. Based on this, the amount of data read from the hard disk 22 at one time and the sleep time are set. If this task has the highest priority level, the read data amount is set to the data amount corresponding to the switching time by the multitask process, and the sleep time is set to 0 (zero). If this task is a task with a low priority level, the read data amount is reduced and the sleep time is set long.

Note that this priority level is assigned to the task in advance, and in the present embodiment, the task of transferring image data from the image reading device 10 to the hard disk 22 is set as the task with the highest priority level. Printer 32
The task of outputting to the host 30 and the task of outputting to the MO are tasks having a low priority level. The read data amount determined at this time is determined based on the amount of data that is completely read out within a time period during which the task is switched by the multitask processing (determined in consideration of the transfer speed.
Since the board is 10 MB / s and the switching time is 100 ms, the maximum read data amount is set to 1 MB).

Then, based on the set read data amount, image data (image data of the image ID set in S11) stored in the hard disk 22 is read out to the main memory 25 (S13). The entire image data of one image stored on the hard disk 22 is several tens of megabytes (MB).
Data is read out as a block of data of B to several MBs (the read data amount determined in S12), and this is repeated a plurality of times to read out all the image data of one sheet. As a result, the image data is not read at a stretch, and this task is not occupied while reading one image from the hard disk 22. That is, it does not occupy for one second as shown in FIG.

An image is read from the hard disk 22 to the main memory 25 by the amount of one read data (S13).
And if all image data has not been read (S
14) The task is put to sleep for the sleep time determined in S12 (S15). Then, when the sleep time has elapsed, the process returns to S13, and the image data is subsequently read. As described above, in the present embodiment, since a sleep is entered for a task with a low priority level, a task with a high priority level is processed correspondingly in order to skip execution of a task in sleep. Can be.

When the reading of all the image data is completed in S14, the image data read into the main memory 25 is subjected to image processing for output (for example, equalization processing, frequency processing, gradation processing, enlargement / reduction processing) as necessary. ) (S16), and output to each output device S17.

Next, a case where a plurality of such tasks are processed (management of a plurality of tasks by the OS) will be described with reference to FIG. 4 which is a time chart at the time of multitask processing. In the present description, a task of storing image data read by the image reading apparatus 10 as shown in FIG. 2 in the hard disk 22 (hereinafter, also referred to as an image reading task), and the hard disk 22 as shown in FIG.
A task for outputting image data stored in the hard disk 22 to the host 30 (hereinafter, also referred to as a printer output task) as shown in FIG. 4) and a task (hereinafter also referred to as an MO output task) for outputting image data stored in the hard disk 22 to the MO device 33 as shown in FIG.
A case in which one task is multitasked will be described.

Note that the priority level becomes lower in the order of the image reading task, the printer output task, and the host output task.
It is assumed that the MO output task has the same priority level as the host output task. Further, in this case, the amount of data read at one time determined in S12 for the printer output task is 1
The sleep time is 300 ms in MB, and the read data amount determined in S12 for the host output task and MO output task is 500 KB and the sleep time is 40
0 ms. In the present embodiment, the task switching time by the OS is assumed to be every 100 ms, and the amount of data stored in the hard disk 22 by the image reading task is:
(Depending on the amount of read data per unit time read by the image reading device 10), the data amount has a size that ends within the switching time.

First, as shown in FIG. 4, the OS starts the processing of the image reading task, and after 100 ms has elapsed, at the end of the image reading task (for example, when any step in FIG. 2 ends), Switch from the image reading task to the printer output task. Then, the OS executes the printer output task (the read data amount set in S12 is 1M).
B, the transfer rate of the SCSI board 21 is 10 MB / s)
Processing is performed for 100 ms. At this time, image data is read from the hard disk 22 by the printer output task. Then, this printer output task enters sleep (sleep time 300 ms).

On the other hand, the OS starts the processing of the host output task 100 ms after the start of the processing of the printer output task, that is, when one reading of the image data is completed. Here, the host output task reads image data from the hard disk 22 for 50 ms because the amount of data read at one time is 500 KB, and then the host output task sleeps (sleep time 400 m).
Enter s). Therefore, the OS sets the host output task to 5
The processing is performed only for 0 ms, and then the host output task to be originally processed has entered sleep. Therefore, this task is skipped, and the processing of the next task, the MO output task, is started. Here, the MO output task reads image data from the hard disk 22 for 50 ms and goes to sleep similarly to the host output task described above. Therefore, O
S processes this MO output task for 50 ms and switches to the next task, the image reading task.

The OS processes the image reading task for 100 ms and switches to the next printer output task. However, at this time, since the printer output task is sleeping, the printer output task is skipped and switched to the next task, the host output task. Further, also in this case, since the host output task is sleeping, it is skipped, and is switched to the next task, the MO output task. Further, also in this case, since the MO output task is sleeping, the task is skipped, and the task is switched to the next task, the image reading task.
That is, the OS processes the image task for 100 ms, then skips the sleeping printer output task, host output task, and MO output task, and subsequently processes the image reading task for 100 ms.

Then, the OS processes the subsequent image reading task for 100 ms, and then processes the next task, the printer output task. At this time, since the sleep time (300 ms) has elapsed and the sleep state has been released, the printer output task executes 1
The process is performed for 00 ms (after this process, the process goes to sleep again). Then, after a lapse of 100 ms, the processing is switched to the next host output task. At this time, the host output task is in a sleep state and is skipped.
The MO output task is also skipped, and the image reading task is processed. That is, the OS processes the image reading task to be processed subsequently for 100 ms, then processes the printer output task for 100 ms, and processes the image reading task again.

As described above, in the present embodiment, of a plurality of tasks using a common device (hard disk 22), a task having a low priority level is put to sleep and / or the time for accessing the device is reduced. Accordingly, the request (real-time property) for a task with a high priority level can be satisfied. In particular, in multitask processing in which task priority control is possible, the number of times of processing of a task can be increased by setting the priority. However, even for one of a plurality of tasks, access such as reading / writing of a large amount of data is restricted. In the case of performing the processing, the method of increasing the number of times of processing cannot secure the real-time property, but according to the present embodiment, this can be facilitated.

In particular, the first task (the task in FIG. 2 in the present embodiment) for storing the image data read by the image reading device 10 in the storage means (the hard disk 22 in the present embodiment), and the first task is stored in the storage means. When the second task for reading out the image data is a second task, the first task is set as a task with a high priority level, and the second task is put to sleep and / or the time for accessing the storage unit is shortened (the data amount to be read is reduced. 2), the capacity of the first memory 12 of the image reading apparatus 10 can be reduced.

In the present embodiment, a task with a low priority level (a task in FIG. 3) is
Has been described, but is not limited to this.
Writing to the hard disk 22 (for example, the host 30
Or writing image data from the MO device 33 to the hard disk 22).

Further, in the present embodiment, the read data amount and the sleep time determined in S12 are maintained until all readings are completed. However, the present invention is not limited to this. The read data amount and the sleep time may be determined according to the priority level of the other task and the present task. In addition, the other task is monitored, and when the other task is started (started), the process returns to S12, and the read data amount and the sleep time per one-time operation according to the priority level of the started task and the present task. May be determined.

In this embodiment, the hard disk 22 has been described as an example of a common device. However, the present invention is not limited to this, and any device occupied by one task may be used.

[0049]

As described in detail above, according to the present invention,
In multitask processing in which a plurality of tasks are switched at predetermined time intervals to process each task, when a plurality of tasks are tasks that access a common device, sleep is set to a task with a lower priority level and / or Alternatively, by shortening one time for accessing a common device, it is possible to satisfy a request with a high priority level that requires real-time properties.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of hardware.

FIG. 2 is a flowchart of a task of storing image data read by an image reading device on a hard disk.

FIG. 3 is a flowchart illustrating a task of outputting image data stored in a hard disk to an output device.

FIG. 4 is a time chart schematically showing the multitask processing of the present invention.

FIG. 5 is a diagram schematically showing a conventional multitask process.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Image reading apparatus 11 Controller 12 1st memory (1st storage means) 20 Computer 22 Hard disk 31 CRT 30 Host computer 32 Printer 33 MO device

Claims (9)

[Claims] 1. A multi-task processing method for processing a plurality of tasks by switching a plurality of tasks at predetermined time intervals, wherein each of the plurality of tasks is a task for accessing a common device. A sleep task is placed in a task having a lower priority level, and a non-sleep task is processed when the sleep task is sleeping. 2. A multi-task processing method for processing a plurality of tasks by switching a plurality of tasks at predetermined time intervals, wherein each of the plurality of tasks is a task for accessing a common device. A multi-task processing method, wherein a task having a lower priority level among the above-mentioned tasks reduces one time for accessing the common device. 3. When a task with a lower priority level among the plurality of tasks is a task of reading image information stored in a storage unit or storing image information in the storage unit, the task stored in the storage unit is stored. 3. The multitask processing method according to claim 2, wherein the image information or all data of the image information to be stored in the storage unit is read or stored in a plurality of times. 4. The task according to claim 2, wherein a sleep is put in the task with the lower priority level, and a task that is not in a sleep state is processed when the task in which the sleep is put is in a sleep state. Multitasking processing method. 5. When the task having a lower priority level among the plurality of tasks is a second task for reading image information stored in the storage means or storing image information in the storage means, the second task 5. The multitask processing method according to claim 4, wherein a sleep mode is set every time data is read from said storage means or stored in said storage means. 6. The multitask processing method according to claim 1, wherein a time of the sleep is changed according to a priority level. 7. A task having a higher priority level among the plurality of tasks is a first task for storing image information read by an image reading device in a storage unit, and a task having a lower priority level among the plurality of tasks. 7. The multi-task processing method according to claim 1, wherein the second task is a second task for reading image information stored in the storage unit or storing image information in the storage unit. . 8. A multi-task processing device for processing a plurality of tasks by switching the plurality of tasks at predetermined time intervals, wherein the plurality of tasks are a first task for storing image information read by an image reading device in a storage unit. Reading out the image information stored in the storage means or storing the image information in the storage means, and reading the image information from the storage means for the second task.
Means for changing the amount of data to be read out each time and setting so that all data of image information read out from the storage means is read out in a plurality of times; and for the second task, one or more times from the storage means Means for setting to sleep for a predetermined time every time reading is performed, wherein when the task to be processed is sleeping, the non-sleeping task is processed. 9. A recording medium for recording a task for accessing a common device with another task, which is used for multitask processing for processing each task by switching a plurality of tasks at predetermined time intervals. According to the level, one time to access the common device and / or a time to sleep after the access is determined. According to the determined time, the common device is accessed and / or after the access. A recording medium on which a task characterized by sleeping is recorded.