JPH10254762A - Real time garbage collection processor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a real time garbage collection processor which can realize high speed real time garbage collection through the use of the whole area of a physical memory. SOLUTION: The garbage collection execution part 12 of CPU 1 rewrites the conversion table 2a of a logic/physical conversion part 2 so that modules which are discrete on the physical address of a main memory 3 are arranged closely on a logical address. The garbage collection execution part 12 generates an idle page by copying the exceeding part of the module to the other page when the size of the module exceeds the page of the main memory.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a real-time garbage collection processing device, and more particularly, to a garbage collection method for solving a fragment of a memory.

[0002]

2. Description of the Related Art Conventionally, in a small-scale / embedded device having no secondary storage or large-capacity memory, a high-performance OS (operating system) for performing garbage collection.
Is difficult or uneconomical to use. In such an apparatus, garbage collection by a copy method is often performed in order to perform garbage collection with a simple algorithm.

As a garbage collection by the copy method, there is a technique disclosed in Japanese Patent Application Laid-Open No. 63-223845. According to the technique described in this publication, when a space on a storage device is divided into two and data that has been discarded because it is not used is accumulated in one space, there is a possibility that an available area is lost or there is a possibility that there is a danger. A method of expanding usable space by transferring data to another space to obtain a new space is used.

In the above technique, when performing real-time garbage collection based on the copy method, a logical address referred to by the processing system is separated from a memory address where data is actually stored, and a table for converting them is used. By providing a dedicated garbage collection processor that allocates new data to memory and moves data for garbage collection and rewrites tables, real-time garbage collection is performed at high speed and the code size of the program is compact. It is possible to.

[0005]

In the garbage collection method according to the conventional copying method described above, since the memory area is divided into two and used, the actually usable memory is reduced to half of the memory amount physically existing. There is a problem that the original processing is stopped for a long time during copying.

If the copy is divided into a plurality of pieces as in the technique described in the above-mentioned publication, the interruption time for each time can be shortened. However, if the processing in the transient state is performed only by software, the processing becomes complicated and the original processing becomes difficult. Has a negative effect. In other words, the technique described in the above publication proposes a reduction in software processing overhead by a method of dividing a copy into a plurality of copies with hardware support by another processor, but there is no change in performing the copy itself, and the memory capacity is reduced. The need to double is not improved. Also, the hardware is quite special, and it is considered undesirable to add a processor solely for this function.

Accordingly, an object of the present invention is to provide a real-time garbage collection processing apparatus which solves the above-mentioned problems, can use the entire area of the physical memory, and can realize high-speed real-time garbage collection. To provide.

[0008]

SUMMARY OF THE INVENTION A real-time garbage collection processing device according to the present invention has a logical address and a logical address used for processing a program when managing a storage area of a memory in units of pages each having a predetermined area. A real-time garbage collection for executing a garbage collection for securing an available area of the memory in an information processing apparatus including a conversion unit for converting a physical address indicating a real address of the memory corresponding to a logical address into a page unit. A processing device, wherein the address table is provided corresponding to the conversion means and holds a correspondence table between the logical address and the physical address, and the correspondence table is rewritten during execution of the garbage collection to rewrite the logical address. A gas that secures the usable area by being close to And a vegetarian collection execution means.

In another real-time garbage collection processing device according to the present invention, in addition to the above-described configuration, when the storage content of the memory to be subjected to the garbage collection is stored beyond the page, the page is deleted. Determining means for determining whether or not a free page can be secured by moving the excess portion to another page; and a portion exceeding the page when the determining means determines that the free page can be secured. For moving to another page.

Another real-time garbage collection processing device according to the present invention is used when managing a storage area of a memory in units of pages each including a predetermined area, and is used at least when executing a module including a program. An address table that stores a logical address and a physical address indicating the real address of the memory in which the module is stored, and a hardware that converts the logical address and the physical address into the page unit when the module is executed. A real-time garbage collection processing device that executes garbage collection for securing an available area of the memory in an information processing device including hardware, and rewrites stored contents of the address table when the garbage collection is performed. Logical address adjacent And a garbage collection execution means for securing the available area by the presence Te.

[0011] Still another real-time garbage collection processing device according to the present invention, in addition to the above-described configuration, is provided that the module is stored in the memory beyond the page and that the module is over the page of the module. Determining means for determining whether a free page can be secured by moving a portion to another page; and a portion of the module exceeding the page when the determining means determines that the free page can be secured. For moving to another page.

That is, the real-time garbage collection processing device of the present invention includes a logical-physical conversion unit, a software module load / execution unit, a memory management unit, a module management unit, and a garbage collection execution unit.

The logical-physical conversion unit is hardware for converting a logical address and a physical address in small units usually called pages, and is usually mounted on a CPU (central processing unit) employing a virtual storage mechanism.

The software module loading / executing unit is a software module creation tool that compiles / links a software execution module in a format that can be executed even if it is placed in any continuous area on a logical address. The module creation tool realizes this function.

The memory management unit refers to the physical address of each logical page, a flag indicating whether or not the page is currently used, and, if used, the module existing in the page is currently executed / referenced. Software that manages a flag indicating whether the

The module management unit is software for managing a module name, a leading logical address and size of each module on the memory, and a flag indicating whether the module is currently executed / referenced.

The garbage collection execution unit rewrites the conversion information held by the logical-physical conversion unit based on the information of the memory management unit during the idle time of the CPU, thereby performing real-time garbage collection processing on the logical address. It is. When the page size is relatively large, the garbage collection execution unit performs a task of increasing the effect of the garbage collection process by performing the address conversion by performing a necessary minimum copy between pages.

[0018]

Next, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing the configuration of one embodiment of the present invention. In the figure, a CPU (Central Processing Unit) 1 is connected to a main memory 3 via a data bus 100. The logical address output when the CPU 1 accesses the memory 3 is converted into a physical address corresponding to the logical address by the logical-physical conversion unit 2 and supplied to the main memory 3.

The CPU 1 includes a software module loading / executing unit 11 and a garbage collection executing unit 1.
2, a memory management unit 13, and a module management unit 14, and these units are realized by software. Here, the garbage collection execution unit 12 includes a copy script 12a, the memory management unit 13 includes a page management table 13a, the module management unit 14a includes a module management table 14a, and the logical-physical conversion unit 2
Has a conversion table 2a.

Software module loading / executing unit 1
1 is an application software module (hereinafter, referred to as an application software module).
Module) is downloaded from a network (not shown), and the module is managed / executed. Here, the fact that a module is "used" means that there is a module in memory (or downloading), which may be currently executing (or referencing) or executing (or referencing) in the future. Means that.

The fact that a module is "executed" means that the module is currently being executed (or being referred to) and cannot be relocated. The management status of the module is managed by the module management unit 14, and based on the information, the memory management unit 1
3 maintains a page management table 13a for managing the usage / execution status of each logical page. The page management table 13a further includes a logical-physical page correspondence table (or a copy thereof) of the conversion table 2a referred to by the logical-physical conversion unit 2. The garbage collection execution unit 12 is activated during the idle time of the CPU 1, and executes garbage collection.

FIGS. 2 and 3 are diagrams showing an example of the garbage collection operation according to one embodiment of the present invention, and FIG. 4 is a flowchart showing the processing operation of the garbage collection execution unit 12 of FIG. FIG. 2 shows a certain module 1,
This shows a state after garbage collection by logical-physical conversion has been performed after modules 2 and 3 have been sequentially downloaded and the module 2 is no longer used and released. In this case, the copy processing for invalidating the original module after copying the module has not been performed. the first,
A garbage collection function by logical-physical conversion operates, although a part of the module 2 is made free in the storage area of the main memory 3 which has been continuously taken and a fragment occurs on a physical address, as shown in FIG. Thus, by changing the correspondence, waste of the main memory 3 can be reduced on the logical address.

FIG. 3 shows the situation after this effect has been further increased by the copying process. That is, a copy of a part of the module 3 indicated by the broken line in FIG.
To a page including a part of the logical address of the conversion table 2a, and further, by changing the logical addresses of the conversion table 2a so that the logical addresses of the module 3 are close to the logical addresses of the module 1, to obtain a larger continuous area. Can be. During the transition from the released state of the module 2 to FIG. 3 through FIG. 2, it is necessary that the module 3 is not executed when garbage collection is actually performed.

The processing operation of the garbage collection execution unit 12 will be described with reference to FIG. When the garbage collection is started, the garbage collection execution unit 12 checks whether or not the module configuration / execution status has been updated (usually, the first check is updated) (step S1 in FIG. 4). If the module configuration / execution status has been updated, the garbage collection execution unit 12 creates a plan for the logical-physical conversion garbage collection that can be realized without copying (step S2 in FIG. 4). If not updated, the previously created plan will be invalid. The planning algorithm simply moves modules that are in use and not running to unused pages that are between busy pages.

When the creation of the plan is completed, the garbage collection execution unit 12 locks so that no other processing operates, and checks again whether the module configuration / execution status has been updated (whether the plan is still valid) ( Step S1 in FIG. 4, if the update has not been performed, the logical-physical conversion unit 2
The garbage collection is executed for (steps S3 and S4 in FIG. 4). At the time of processing execution, the module configuration information is updated.

When garbage collection by logical-physical conversion is not possible (once garbage collection is executed, a new valid garbage collection cannot be executed unless the module configuration / execution status is updated), the garbage collection execution unit 12 Checks whether it is possible to create a free page inside the used area by the copy process (step S5 in FIG. 4). At this time, the copy size per one time is at most half of the page size.

When the check is completed, the garbage collection execution unit 12 locks so that no other processing operates, and checks again whether the module configuration / execution status is updated (whether the plan is still valid) (FIG. 4
Step S6). If the update has not been performed, the garbage collection execution unit 12 executes one copy process to update the module configuration information (steps S7 and S7 in FIG. 4).
8) Return to step S1. In this case, there is a high possibility that a new effective logical-physical conversion garbage process can be executed. Also, garbage collection is no longer possible without a valid copy process,
The process ends. When the module configuration / execution status changes, there is a possibility that this process is called again.

It is economically desirable that a network terminal device usually has no secondary storage such as a hard disk device, has a minimum memory, and uses it efficiently. In order to process different requests for each user in these terminal devices, generally, only the network communication software is installed in the terminal device itself, and modules are downloaded from a center (not shown) and used whenever necessary. Is customary.

In such a network terminal device, the size of modules to be downloaded and the order of download are undefined, and the order and timing of their release are also undefined. Is easy to occur. Further, in such a terminal device, CPU waiting time such as network communication processing time and user input waiting time at the time of downloading is easily generated, and the use state of the module is easily managed. Is easy to raise.
Furthermore, it is an essential condition that generally downloaded modules operate at any address on a logical address (relocatable), which also meets the conditions of the present invention.

As a specific example of one embodiment of the present invention, VOD
(Video on demand) terminal devices. In these terminal devices, the module to be downloaded is a hierarchical menu of services provided by each server. For example, a server that provides an online shopping service may provide a menu for selecting a product category in an initial menu, and each item may have a more internal menu hierarchy.

In this case, the method of downloading and releasing the software module is performed as follows.
The user selects the clothes menu (module 2) from the initial menu (module 1). Module 2 is downloaded after Module 1. Think back and return to the initial menu. Select the home appliance menu (module 3) from the initial menu. Module 3 is downloaded after Module 2.

At this point, the clothes menu (module 2)
Becomes unnecessary, and the situation as shown in FIG. 2 results. The size of each menu depends on how much image data (still image, moving image) is included in the menu. However, multimedia terminal devices usually include at least several hundred kilobytes of image data. Even if the page size is about 100 kilobytes, a sufficient effect can be obtained. In many recent ordinary CPUs, the page size can be selected in the order of kilobytes to megabytes (for example, PPC4 which is often used in VOD terminal devices).
03, it is possible to select from a minimum of 1 Kbyte to a maximum of 16 Mbytes), which can sufficiently respond to the garbage collection request of the present invention. Further, by setting the page size to an appropriate value, it is possible to control the level of detail of garbage collection, and it is possible to balance performance and functions.

In this embodiment, for example, when the user returns from the home appliance menu to the initial menu again, the home appliance menu module (module 3) is used by utilizing the input waiting time during which the user selects the menu. It is also possible to move as shown in FIG. By doing so, even if the home appliance menu is selected again after the movement and is started, the home appliance menu can be displayed without downloading with little memory fragment.

As described above, when the garbage collection execution unit 12 of the CPU 1 is started, the module configuration information of the conversion table 2a of the logical-physical conversion unit 2, that is, the logical address of the conversion table 2a is rewritten to make the logical addresses close to each other. Garbage collection can be performed with minimal copy processing, so that the entire area of physical memory can be used without adding new dedicated hardware, and high-speed real-time Garbage collection can be realized.

[0035]

As described above, according to the present invention, at least a logical address used for executing a module including a program and a physical address indicating a real address of a memory in which the module is stored are stored in association with each other. By rewriting the inside of the address table to perform garbage collection to secure a usable area of the memory so that the logical addresses are close to each other,
There is an effect that the entire area of the memory can be used and high-speed real-time garbage collection can be realized.

[Brief description of the drawings]

FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention.

FIG. 2 is a diagram illustrating an example of a garbage collection operation according to an embodiment of the present invention.

FIG. 3 is a diagram illustrating an example of a garbage collection operation according to an embodiment of the present invention.

FIG. 4 is a flowchart illustrating a processing operation of a garbage collection execution unit in FIG. 1;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 CPU 2 Logical-physical conversion part 2a Conversion table 3 Main memory 11 Software module load / execution part 12 Garbage collection execution part 12a Copy script 13 Memory management part 13a Page management table 14 Module management part 14a Module management table

Claims (4)

[Claims] 1. A logical address used for processing a program when a storage area of a memory is managed in units of pages each including a predetermined area, and a physical address indicating a real address of the memory corresponding to the logical address. Is a real-time garbage collection processing device that executes garbage collection for securing an available area of the memory in an information processing apparatus including a conversion unit that converts the And an address table for holding a correspondence table between the logical address and the physical address, and a garbage for reserving the correspondence table at the time of executing the garbage collection so that the logical addresses are present in close proximity to secure the usable area. Real-time garbage having collection execution means Collection processing device. 2. When the storage contents of the memory to be subjected to the garbage collection are stored beyond the page, a portion beyond the page is moved to another page to secure a free page. The apparatus according to claim 1, further comprising: a determination unit configured to determine whether or not the available page is available, and a unit configured to move a portion exceeding the page to another page when the determination unit determines that the empty page can be secured. 1
A real-time garbage collection processor as described. 3. A logical address used when managing a storage area of a memory in units of pages each including a predetermined area, and at least a logical address used when executing a module including a program and the memory storing the module. The information processing apparatus includes an address table that stores physical addresses indicating physical addresses of the modules in association with each other, and hardware that converts the logical addresses and the physical addresses into the page units when the module is executed. A real-time garbage collection processing device that performs garbage collection for securing an available area, wherein the content stored in the address table is rewritten at the time of performing the garbage collection so that the logical addresses are close to each other. Garbage to secure usable area A real-time garbage collection processing device comprising a collection execution unit. 4. When the module is stored in the memory beyond the page, whether or not a free page can be secured by moving a portion of the module beyond the page to another page Determining means for determining
4. The real-time garbage collection process according to claim 3, further comprising: means for moving a portion of the module beyond the page to another page when the determination means determines that the empty page can be secured. apparatus.