JP2001142649A - Storage medium scheduler, real time system and scheduling method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a storage medium scheduler, a real time system and a scheduling method which normally process stream data that have temporal constraint and are severely managed and which also normally process non- stream data. SOLUTION: Request execution orders are switched in real time so as to optimize processing by having two types of queues to a request provided with a parameter, processing that plans a request execution order according to the parameter and processing that scans the queues and executes an optimum request.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for scheduling a request for data including stream data to a storage medium, and a technique for scheduling a processing order by a parameter added for a request to the storage medium. When stream data and non-stream data are handled in a storage medium, information for scheduling is added to a request for the storage medium, and a request order is set based on the added information so that stream data is not lost. By performing request scheduling, the present invention relates to a storage medium scheduler, a real-time system, and a scheduling method that normally process stream data that is tightly managed due to time constraints and also normally process non-stream data. .

[0002]

2. Description of the Related Art In a conventional storage medium, data recorded on the storage medium is almost time-limited data because of the processing capacity and storage capacity of the system and the request processing speed of the storage medium. Is a normal processing method in which requests are processed in the order in which requests are issued.

Conventionally, there is no time constraint on data handled by a storage medium, so that even if a large amount of request processing time is required, if the request is processed normally, no system problem occurs. Therefore, there is no problem in a processing method in which requests are processed in the order in which the requests are issued.

However, with the recent increase in storage capacity and speed of storage media, and the improvement in system processing capability for controlling storage media, it has become possible to handle data that has been difficult to handle until now and has time constraints. The data requiring the time constraint is mainly moving image and audio data. Data having such temporal continuity is called stream data. Since such stream data is image / audio data, if data is not stably provided, data to be reproduced or recorded is not provided. Dropout occurs, and the stream data is not normally reproduced / recorded.

Next, a description will be given of an example in which stream data is handled by the above-mentioned conventional request processing method and a 5-minute stream is composed of five 1-minute stream data. Assuming that the start time of the first stream data is 00:00:00 (h: m: s), the second stream data cannot be normally reproduced unless it has been read by 00:01:00. Similarly, the third is 0
0:02:00, the fourth is 00:03:00, the fifth is 00:04:00, and the processing start time of the stream data to be provided starts from the start time of the stream ( Recording to the storage medium or reproduction from the storage medium must be completed by N-1) × “stream data time per stream”. In this example, since all the requested requests are stream data, there is no problem if the storage medium has enough bandwidth to process the stream data in the conventional processing method, but a problem occurs if the bandwidth is insufficient.

Next, a case where a request for stream data and a request for non-stream data are mixed in a request will be described. When five requests are issued, the first, second, fourth, and fifth requests are for stream data, and the third is for non-stream data requests, the first, fourth, and fifth requests are stored in the storage medium as described above. If there is enough bandwidth, there is no problem with stream reproduction / recording.

In the case of the conventional processing method, after the first and second stream data requests are processed,
The request for the non-stream data is processed, but if the processing end time exceeds the reproduction time of the fourth stream data, the time lag between the second stream data and the fourth stream data as a whole stream is considered. Will occur.

[0008] Further, in the case of recording, a lack of time lag time is caused, and in the case of reproduction, a stream is stopped for the time lag time, and a normal stream cannot be constructed.

In the case of stream reproduction, since stream data is read from a storage medium, data recorded on the storage medium is not affected. Therefore, if the same stream is reproduced again, normal reproduction can be performed. Although it is possible, if the situation is the same, the normal stream cannot be reproduced again, which is not a preferable state for the system.

In the case of stream recording, a time lag is fatal. If the stream data recorded on the storage medium is missing, if the stream data being recorded is data that is provided only once, the missing part cannot be recorded again, so the stream data being recorded is Is incomplete and has the worst results for the system.

As described above, the conventional request method for a storage medium is not very suitable for handling stream data having a time constraint. Therefore, in order to handle stream data, it is necessary to schedule a request in consideration of real-time properties.

[0012]

However, the biggest problem with the conventional method of processing requests in the order of issuance to the storage medium is that stream data having a time constraint and non-stream data having no time constraint. In the case of a request configuration in which data is mixed, the degree of completion of a stream depends on the request processing time of non-stream data.

Further, the number of combinations of requests to the storage medium is infinite, and while stream data is normally handled,
To process non-stream data normally, a flexible request scheduling method is required. Therefore, there is a problem that it is extremely difficult to handle a mixture of stream data and non-stream data in a storage medium unless a unique request scheduling method is used so that stream data can be processed normally.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an object of the present invention is to provide information for scheduling in a request for a storage medium when the storage medium handles stream data and non-stream data. And performs request scheduling based on the added information so that a request order does not cause a loss of stream data. Another object of the present invention is to provide a storage medium scheduler, a real-time system, and a scheduling method that normally process non-stream data.

[0015]

The gist of the present invention is to provide a storage medium scheduler that optimally processes a request for a storage medium, and includes a priority, a time limit, an access destination inside the storage medium, Means for generating a first queue in which priority is given to optimization of an access destination in the storage medium in response to a request having a parameter for specifying an expiration date, and a second queue optimized in time priority Means for generating a matrix; means for planning an execution order for requests based on parameters of the priority, the time limit, and an access destination inside the storage medium such that processing of the storage medium is optimized; Means for scanning a first queue and the second queue, executing an optimal request, and updating the first queue and the second queue; Means for transmitting an est execution result to a request requester, wherein a queue for optimizing an access destination in the storage medium is given priority for a request for the storage medium, and a queue optimized for time priority. , And by referring to the two types of queues, scans the queue in which priority is given to optimizing the access destination in the storage medium. If any of the queues exceeds the time limit, the request execution order Processes requests in the order of the queue optimized for time priority, and processes the requests in the order of the queue in which optimization of the access destination in the storage medium is prioritized if there is room for the time limit. The storage medium scheduler has a configuration in which the request execution order is switched in real time. According to a second aspect of the present invention, there is provided a storage medium scheduler according to the first aspect, wherein the storage medium includes video data for multimedia use including video-on-demand. The gist of the invention according to claim 3 resides in the storage medium scheduler according to claim 1, wherein the storage medium includes audio data for multimedia use including video-on-demand. The gist of the invention described in claim 4 is that the storage medium includes data other than video and audio for multimedia use including video-on-demand. Exists. According to a fifth aspect of the present invention, there is provided a storage medium scheduler according to the first aspect, further comprising means for designating the priority according to a type of data recorded on the storage medium. According to a sixth aspect of the present invention, there is provided a storage medium scheduler according to the first aspect, wherein the storage medium is a magnetic storage disk. The gist of the invention according to claim 7 resides in the storage medium scheduler according to claim 1, wherein the storage medium is an optical storage disk. Also,
The gist of the invention according to claim 8 resides in the storage medium scheduler according to claim 1, wherein the storage medium is a magnetic tape. The gist of the invention described in claim 9 is to optimize the access destination inside the storage medium in response to a request including parameters for specifying priority, time restriction, access destination inside the storage medium, and expiration date. A priority queue and a time-optimized queue are configured, and the optimization of the access destination in the storage medium is normally performed in the order of the priority queue. When a request exceeding the limit is to be processed, the processing order is changed to a queue optimized for time priority and the request is processed, and all requests in both queues exceed the time limit. If not, there is scheduling means for scheduling so that the optimization of the access destination inside the storage medium is processed again in the order of the priority queue. It consists in real-time system according to claim Rukoto. Further, the gist of the invention according to claim 10 is that, when a new request is generated, the scheduling unit gives priority to optimization of an access destination in the storage medium based on the parameter of the request. 10. A real-time system according to claim 9, further comprising means for reconstructing the contents of the queue optimized for time priority. The gist of the present invention resides in a real-time system according to claim 10, comprising two queues and means for switching a processing order in real time according to the state of a request to be processed. . The gist of the invention according to claim 12 is a scheduling method for scheduling a request execution to the storage medium having parameters for specifying a priority, a time limit, an access destination inside the storage medium, and an expiration date. A first queue in which optimization of an access destination in the storage medium is prioritized based on a parameter added to the request, and a second queue optimized in time priority. Priority is given to the steps of: performing a reconfiguration of the first queue and the second queue when a new request is requested; and optimizing an access destination inside the storage medium. Checking the time limit existing in the queue when the request is processed, and requesting the time limit existing in the time-optimized queue. A time-optimized waiting process when a request existing in a queue that prioritizes optimization of an access destination inside the storage medium to be executed exceeds the time limit. Shifting the execution order to the queue, and, when the requests existing in the queue optimized for time priority to be executed are within the time limit, optimization of the access destination inside the storage medium is prioritized. And a step of shifting the execution order to the queue, and immediately stopping the processing of the request to be executed when the request to be executed has exceeded the expiration date.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS First, the gist of the present invention will be described.
Generally, in a recording system that handles stream data, “priority”, “time limit”, and “expiration date” are used as parameters of a request. In the present invention, it is defined as follows.

Time restriction: Time at which processing is desired to start. Recording and playback are not necessarily interrupted even if this time is not reached. The time limit indicates a time limit at which processing can be completely performed without any abnormality such as a missing request for processing.

Expiration date: A time at which a part of recording / reproduction is interrupted if the processing is not started by this time. Since the request whose expiration date has passed is meaningless for the stream even if the processing is executed, it is used as a material for determining whether or not the request can be executed.

Priority: The priority at which the request is processed. In the present embodiment, the priority is used as auxiliary information for the determination process when the above two parameters are the same.

The present invention is roughly divided into two components. One component is a block characterized by examining a parameter added to a request for a storage medium and generating two types of queues: a time-limited order and an access destination order within the storage medium. .

This has a function of immediately examining the two queues that have been created when a new request request is generated, and reconstructing the respective queues again.

Another component examines the parameters of the request to be processed in the currently used queue among the two created queues, and if the time exceeds the time limit, The block is characterized by executing the first request from the queue in the order of the time limit, and executing the first request from the access destination order queue in the storage medium if the time limit is not exceeded.

Another feature of the present invention is that it has a function of deleting a processed request from the two queues in order to prevent re-execution of a processed request.

The greatest feature of the present invention is that the above-mentioned two types of queues are used alternately according to the result of examination of the retrieved requests.

Next, the operation of the present invention will be described. A request for a storage medium is issued with information for request scheduling added. The issued request examines parameters for scheduling, and first generates a queue in the order of the time limit and a queue in the order of the access destination in the storage medium. At this time, if the parameters used at the time of creation are the same in both queues,
The priority in the parameter determines the order in the queue.

When the generation of the two queues is completed, the queue generation block notifies the request execution block of the completion of the queue generation. This queue creation completion notification is notified when a request in the queue is registered for the first time, and is not notified when there is one or more requests in the queue.

When a new request is generated, the above operation is performed and the contents of each queue are constantly updated. When the request execution block receives the notification of the completion of the queue creation, it examines the current use queue.

The request parameters are checked from the queue of the check result, and if the request exceeds the time limit, the request is executed in order from the queue in the order of the time limit. Delete the registered executed request from the queue.

If the request does not exceed the time limit, the request is executed sequentially from the access destination sequential queue in the storage medium, and the executed request is deleted from each queue in the same manner as before.

If the request to be executed has exceeded its expiration date, the request is meaningless even if it is executed, so that the request is not executed due to a reduction in the bandwidth load on the storage medium, and the request is expired and the abnormal termination is requested. Notify the original.

As described above, the two types of queues, ie, the request queue which is not subject to the time constraint and the request queue taking the time constraint into consideration, are alternately used depending on the request status. It is possible to process certain data requests in an optimal order. Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a configuration diagram of a storage medium scheduler for explaining a first embodiment of the present invention. In FIG. 1, reference numeral 100 denotes a queue generation block, 101 denotes a time limit order queue, 102 denotes an access destination order queue in a storage medium, 103 denotes a request execution block, 104 denotes a storage medium controller, and 105 denotes a storage medium. I have.

Referring to FIG. 1, in the embodiment of the present invention, a storage medium 105, a queue generation block 100, a time limit order queue 101, an access destination order queue 102 in the storage medium, and an executed request A request execution block 103 having a function of removing the request from the queue;
A storage medium controller 104 is provided.

The queue generation block 100 first sets a time limit based on parameters such as priority, time limit, access destination in the storage medium 105, and expiration date added to the request when the request is generated. Investigate,
The request is registered in the time limit order queue 101 so as to be processed in the time limit order. Subsequently, the access destination inside the storage medium 105 is checked, and the request is registered in the access destination order queue 102 inside the storage medium so that the request is processed in the order of the access destination inside the storage medium 105. At this time, if there is no request in the queue and this is the first registration request for the current queue state, the request execution block 103 is in a state of waiting for request registration. This is executed for the execution block 103. If there is a registered request inside each queue, newly registered requests are added, and all requests in the queue are reconfigured according to the respective queue conditions.

FIG. 2 shows an example of request order generation in a queue, and shows the inside of a time-limited order queue 101 generated by the queue generation block 100 and used for reconfiguring requests in the queue. In FIG. 2, 11
0 indicates the inside of the previously generated queue, 111 indicates the registered request, and 112 indicates the inside of the queue after the order is regenerated. H added to the request in FIG.
The numerical value expressed in the form of h: mm: ss indicates the time limit of the request.

The previously created queue interior 110 shown in FIG. 2 represents the state before a new request request is issued. At this time, a new request (Fig. 2
Is issued, the queue generation block 100 re-examines the requests in the queue and regenerates an appropriate order.
The time limit for new requests in this case is Request
Since it corresponds to the middle between st2 and Request3, the regenerated queue is the queue interior 112 after the order regeneration, as shown in FIG. In this case, the time limit order queue 101 is used as an example, but the same applies to the access destination order queue 102 inside the storage medium.

The request execution block 103 checks the currently used queue after executing the request. As a result of the investigation, if there is no request in the queue, execution is suspended, and a state of waiting for registration of a new request is entered.
If the request exists, the first request in the queue is taken out and the process proceeds to the request execution process. The retrieved request has been retrieved from the same queue as the previously processed request.

The request execution block 103 examines the above-mentioned parameters of the fetched request. If the time exceeds the time limit, the request execution block 103 fetches the next request to be executed from the time limit queuing queue 101, and if the time exceeds the time limit. When there is no request, the request to be executed next is taken out from the access destination sequential queue 102 in the storage medium, and the storage medium controller 104 is requested to access the storage medium 105 to make a request to the storage medium 105.

When the command to the storage medium controller 104 is executed, the request execution block 103 deletes the processed request from the two queues.

Next, the operation of the storage medium scheduler (scheduling method) with reference to the flowcharts of FIGS.
Will be described. 3 and 4 show the queue generation block 1.
FIG. 3 is a flowchart showing an operation overview of FIG.
4 shows the operation of the first half of the processing steps of the queue generation block 100 of FIG. 1, and FIG. 4 shows the operation of the queue generation block 10 of FIG.
0 shows the operation of the latter half of the processing step of 0.

Referring to FIG. 3, in the present embodiment, first, when a request is registered, the value of the time limit among the parameters added to the request is checked, and the value of the time limit is temporarily stored. It is held (step S100).
Subsequently, it is checked whether there is any unprocessed request remaining in the time limit order queue 101 (step S101).

At this time, if there is no unprocessed request in the examined queue, the request is registered in the time-limited queue 101 as it is. If there are unprocessed requests remaining, is there a time limit value of the registered request temporarily held earlier that is the same as the time limit value of the unprocessed request remaining in the queue? Is checked (steps S102 and S103).

If there is no request having the same time limit value in the queue, the request is inserted into the time limit order queue 101 as a registration request, and the process proceeds to the process of regenerating the queue. When a request having the same time limit value is found, the priority of the request and the registration request is checked, and which request has a higher priority (step S104,
S105).

When the priority of the registered request is higher than that of the request in the queue, the request is inserted immediately before the request having the same time limit value in the queue. S106, 1
07).

Subsequently, the order of the time limit queue 101 is checked based on the value of the time limit of the registration request, and the request is inserted into the queue in the corresponding order (regeneration of the order in the queue). : Step S108). Subsequently, request processing is performed on the access destination sequential queue 102 in the storage medium, which is another queue.

Here, the order of access destinations in the storage medium 105 will be described. In the following description, the case where the storage medium 105 is a disk is described, but the storage medium 105 according to the present invention is not limited to a disk storage system, but includes all storage media that are sequentially accessed.

When the storage medium 105 is a disk, it has a number of tracks on the surface. The tracks are arranged concentrically from the center of the disk, and each is assigned a track number. Inside the track, there are areas divided into small units. This area is called a sector. The disk is accessed on a sector-by-sector basis.

The access request to the disk is “track 1, 5 sector”, “track 5, 2 sector”, “track 1, 10 sector”, “track 5, 1”.
When issued in the order of "3 sectors", the request is processed in the order of issuance in the conventional request method, and the head for reading the sector moves from track 1 to track 5 to track 1 to track 5, so that these four Three head movements are required to fulfill the request. Since a certain amount of time is required for the movement of the head, considering the processing time, the number of times of head movement is preferably as small as possible. Also, when the head moves over a track, if the moving amount of the head is large, the moving time of the head becomes long.

In the request processing in the order of access destinations in the storage medium 105 used in the present invention, in the case of a disk, accesses to the same track are continued in ascending (or descending) order, and accesses to one track are 1 in number. Requests are issued so that track numbers are consecutive in ascending order (or descending order) even in the case of access over a large number of tracks only once, so that the number of head movements or the amount of head movement is minimized. Operate.

In the case described above, the present invention relates to the storage medium 1
The requests issued in the order of the access destinations in the 05 are “track 1, 5 sector”, “track 1, 10 sector”,
"Track 5, 2 sectors" and "Track 5, 13 sectors", the movement of the head is changed from track 1 to track 5, and the number of times of movement of the head is only one. For example, if the moving time per head is 10 msec, the processing is completed 20 msec earlier than the conventional method.

Next, referring to FIG. 4, similarly to the time limit order queue 101, the value of the access destination among the parameters added to the registration request is checked, and the value of the access destination is temporarily stored. (Step S109).

Subsequently, it is checked whether or not unprocessed requests remain in the access destination sequential queue 102 in the storage medium (step S110).

At this time, if there is no unprocessed request in the examined queue, the request is registered as it is in the access destination sequential queue 102 in the storage medium. If unprocessed requests remain, is there an access destination value of the registered request temporarily held earlier that is the same as the access destination value of the unprocessed request remaining in the queue? (Step S
111, S112).

If no request having the same access destination value exists in the queue, the registration request is inserted into the access destination sequential queue 102 in the storage medium, and the order in the queue is changed. Move on to the regeneration process. If a request having the same access destination value is found, the priority of the request and the registration request is checked, and which request has a higher priority is checked (steps S113 and S114).

When the priority of the registered request is higher than that of the request in the queue, the request is inserted immediately before the request having the same access destination value in the queue. (Step S
115, 116).

The order of the access destination order queue 102 in the storage medium is checked from the value of the access destination of the registration request, and the request is inserted into the queue in the corresponding order. (Regeneration of the order in the queue) (Step S
117).

For the requests in the two queues, the same request is stored, although the processing order is different. Therefore, if one of the queues is examined and the request inserted into the queue does not have a registered request in the queue and the inserted request is the first request in the queue, The request execution block 103 is notified of request registration.
If it is not the first request, it waits for registration of a new request (steps S118, S119).

FIG. 5 shows the request execution block 10 of FIG.
13 is a flowchart for explaining the operation of the third processing step. In the present embodiment, the queue generation block 1
Upon receiving the request registration notification from 00, the request execution block 103 starts operating. After the operation starts,
The request execution block 103 determines whether the queue from which the request is currently being taken out is the time-limited queue 101 or the access-destination queue 1 in the storage medium.
02 is checked with reference to a use queue flag (described later) (step S200).

Subsequently, it is checked whether a request exists in the queue currently being used, and if no request exists, a request wait state is entered (step S).
201, 202).

Subsequently, the parameters of the request located at the head of the queue are checked, and if the expiration date is exceeded, the expiration date is notified to the requesting requester and the request is deleted from the queue. later,
The investigation in the queue is performed again (steps S203 and S20).
4,205).

If the request has not expired, the time limit parameter is checked. At this time, if the use queue flag (to be described later) is the time limit order queue 101, only the first request is checked. If the use queue flag is the access destination order queue 102 in the storage medium, all requests in the queue are checked. To investigate the. That is, in the case of the access destination sequential queue 102 in the storage medium, it is checked whether at least one request exceeding the time limit exists in the queue.

If the time limit of the request is exceeded, a flag is set in the time limit order queue 101. If the time limit is not exceeded, a flag is set in the access destination order queue 102 in the storage medium. (Steps S206, 207, 208). At this point, the queue currently used is determined, and the first request in the queue is executed (step S209).

Thereafter, the request execution result is notified, the executed request is deleted from the time limit order queue 101 and the access destination order queue 102 in the storage medium, and the processing order of the requests remaining in the queue is changed. Reconstruct (Steps S210, 211).

Thus, the processing of one request is completed. When the processing of the request is completed, it is checked again whether the request remains in the queue, and if there is no request, a new request registration wait state is entered. If there is, the processing of the remaining requests is performed according to the above-described procedure.

As described above, according to the present embodiment, the present invention is configured as described above, and has the following effects. First, the first effect is that the balance between disk processing and noise can be achieved even for stream data only. The reason is that priority is given to the time-constrained queue, and if time constraints allow, priority is given to the access-destination queue.If there is sufficient disk processing capacity, the access-destination queue is given priority. As a result, the moving distance of the head becomes shorter, and the noise can be reduced.

A second effect is that even when stream data and non-stream data coexist, the demands on the disk system can be realized to the maximum.

The third effect is that the non-stream data is generally given less time constraints compared to the stream data, and the time constraint processing is prioritized. Is possible to minimize the influence on stream data having a strong. Non-stream data generally has less time constraints than stream data. Since the present invention gives priority to the time constraint processing, even when non-stream data is mixed, it is possible to minimize the influence on the stream data having a strong time constraint.

(Second Embodiment) The storage medium scheduler can be realized by software on the system.
00, the request execution block 103, the time limit order queue 101, and the access destination order queue 102 in the storage medium can be realized by hardware.

For example, two queues are constituted by dedicated memories, and the functions of the queue generation block 100 and the request execution block 103 are realized by using a dedicated LSI (ASIC) for a specific customer, and the like. Dedicated LS
With a configuration in which the storage medium controller 104 and the storage medium 105 are connected to I (ASIC), the function of the present invention can be realized.

Also, a queue generation block 100, a request execution block 103, and a time limit order queue 101
If the functions of the storage medium 105 as well as the functions of the access destination sequential queue 102 inside the storage medium are also implemented as hardware (ASIC), all the functions of the present invention can be realized with one hardware. Become.

It should be noted that the present invention is not limited to the above embodiments, and it is clear that the embodiments can be appropriately modified within the scope of the technical idea of the present invention. Further, the number, position, shape, and the like of the constituent members are not limited to the above-described embodiment, and can be set to numbers, positions, shapes, and the like suitable for carrying out the present invention. In each drawing, the same components are denoted by the same reference numerals.

[0072]

Since the present invention is configured as described above, the following effects can be obtained. First, the first effect is that the balance between disk processing and noise can be achieved even for stream data only. The reason is that priority is given to the time-constrained queue, and if time constraints allow, priority is given to the access-destination queue.If there is sufficient disk processing capacity, the access-destination queue is given priority. As a result, the moving distance of the head becomes shorter, and the noise can be reduced.

The second effect is that even when stream data and non-stream data are mixed, the request to the disk system can be realized to the maximum.

The third effect is that the non-stream data is generally given a smaller time constraint than the stream data, and the time constraint processing is prioritized. Is possible to minimize the influence on stream data having a strong. Non-stream data generally has less time constraints than stream data. Since the present invention gives priority to the time constraint processing, even when non-stream data is mixed, it is possible to minimize the influence on the stream data having a strong time constraint.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a storage medium scheduler for explaining a first embodiment of the present invention.

FIG. 2 is an example of request order generation in a queue.

FIG. 3 is a flowchart for explaining the operation of the first half of the processing steps of the queue generation block of FIG. 1;

FIG. 4 is a flowchart for explaining the operation of the latter half of the processing steps of the queue generation block of FIG. 1;

FIG. 5 is a flowchart illustrating an operation of a processing step of a request execution block in FIG. 1;

[Explanation of symbols]

 Reference Signs List 100: Queue generation block 101: Time limit order queue 102: Access destination order queue inside storage medium 103: Request execution block 104: Storage medium controller 105: Storage medium 110: Inside of queue previously generated 111 … Registered request 112… inside the queue after the order is regenerated

Claims (12)

[Claims] 1. A storage medium scheduler that optimally processes a request for a storage medium, wherein the request includes parameters for specifying a priority, a time limit, an access destination inside the storage medium, and an expiration date. Means for generating a first queue in which priority is given to optimization of an access destination in the storage medium, means for generating a second queue optimized in time priority, and optimization of processing of the storage medium Means for planning an execution order for requests based on the priority, the time limit, and parameters of an access destination inside the storage medium, and scanning the first queue and the second queue. Means for executing an optimum request and updating the first queue and the second queue, and a means for transmitting a result of the request execution to a requestor. Preparative comprising a queue that has been prioritized to optimize the storage medium inside the access destination request to the storage medium, to create two kinds of queue of optimized queue at time priority,
With reference to the two types of queues, the queues in which priority is given to optimization of the access destination in the storage medium are scanned. If any of the queues exceeds the time limit, the request execution order is optimized with time priority. The request is processed in the order of the queue, and if there is a margin in the time limit, the request execution order is processed by processing the request in the order of the queue in which optimization of the access destination in the storage medium has priority. A storage medium scheduler having a configuration for switching in real time. 2. The storage medium scheduler according to claim 1, wherein the storage medium includes video data for multimedia use including video on demand. 3. The storage medium scheduler according to claim 1, wherein the storage medium includes audio data for multimedia use including video on demand. 4. The storage medium scheduler according to claim 1, wherein the storage medium includes data other than video and audio for multimedia use including video on demand. 5. The storage medium scheduler according to claim 1, further comprising means for designating the priority according to a type of data recorded on the storage medium. 6. The storage medium scheduler according to claim 1, wherein said storage medium is a magnetic storage disk. 7. The storage medium scheduler according to claim 1, wherein said storage medium is an optical storage disk. 8. The storage medium scheduler according to claim 1, wherein said storage medium is a magnetic tape. 9. A queue in which optimization of an access destination in the storage medium is prioritized with respect to a request including parameters for specifying a priority, a time limit, an access destination in the storage medium, and an expiration date; A queue optimized by priority is configured, and requests exceeding the time limit are processed in requests that are normally processed in the order of the queue in which optimization of the access destination in the storage medium is prioritized. When trying to do so, change the processing order to a queue optimized for time priority and process the request,
If all requests in both queues do not exceed the time limit, scheduling means for scheduling so that the optimization of the access destination inside the storage medium is again processed in the priority queue order A real-time system characterized by the following. 10. The scheduling unit according to claim 1, wherein, when a new request is generated, a priority is given to a queue in which optimization of an access destination in the storage medium is prioritized based on the parameter of the request, and a time priority is optimized. 10. The real-time system according to claim 9, further comprising means for reconstructing the contents of the queue. 11. The real-time system according to claim 10, comprising two queues, and means for switching a processing order in real time according to a state of a request to be processed. 12. A scheduling method for scheduling execution of a request to said storage medium having parameters for specifying a priority, a time limit, an access destination inside the storage medium, and an expiration date, the method being added to the request. Configuring a first queue prioritizing the optimization of an access destination inside the storage medium based on the parameters, and configuring a second queue optimized with a time priority; Reconfiguring the first queue and the second queue when requested; and the time in the queue where optimization of access destinations within the storage medium is prioritized. Checking the time limit when processing the request; and checking the time limit existing in the time-optimized queue when processing the request. When the request existing in the queue that prioritizes the optimization of the access destination inside the storage medium to be executed exceeds the time limit, the execution order is changed to the time-optimized queue. Transferring, and if the request present in the time-optimized queue to be executed is within the time limit,
Shifting the execution order to a queue in which optimization of the access destination in the storage medium is prioritized; and immediately stopping the processing of the request to be executed when the request to be executed has exceeded the expiration date. A scheduling method, comprising: