JP2000311110A - Memory managing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accelerate bit map retrieving processing for memory management. SOLUTION: A maximum continuous empty area length managing means 104 compares the number of required bit map areas with a maximum continuous empty area length in a bit map and judges the presence/absence of an empty area capable of continuously securing the required bit map areas. When there is an empty area, a bit map secure managing means 110 calculates a position, where bit map securing operation is performed just before, inside the bit map. An empty bit map retrieving means 105 starts the retrieval of the empty area from that position. At such a time, when the number of required bit map areas exceeds one word, first of all, a word unit bit map retrieving means 108 retrieves the empty area for the unit of a word just for words in the required area size and next, a bit unit bit map retrieving means 109 retrieves the empty area for the unit of a bit concerning an excessive part or areas for one word or less.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a system for performing memory management using a bitmap, and more particularly, to a memory management device for performing a bitmap search process for searching for a free area.

[0002]

2. Description of the Related Art For example, Japanese Patent Application Laid-Open No. Hei 8-221317 discloses that
A part of the memory is divided into a plurality of memory cells of a fixed length, bits are assigned to the plurality of memory cells, and a bit map that stores bit values indicating a used / unused state of the memory cells is managed. There is disclosed a technique for realizing efficient memory management irrespective of fixed-length / variable-length memory by providing a data area and managing this bitmap to secure / release the memory.

[0003]

However, according to the prior art, as the total size of the memory to be allocated increases, the bitmap area also increases in proportion thereto. Therefore, when searching for the bitmap, since the search is performed from the beginning, when the empty area is located at the rear, the larger the bitmap area is, the longer the time until the result is obtained is proportionally increased. Would. In addition, since a bitmap search is used, a determination is made in units of bits in order to separate use / non-use. If a large space is required, the number of determinations increases in proportion to the size of the bitmap area. For this reason, there is a problem that it takes time to search for unused bits to secure a memory.

[0004] The present invention has been made in view of the above circumstances, and has as its object to provide a memory management device that can speed up bitmap search processing.

[0005]

According to the first aspect of the present invention, a part of a memory is divided into a plurality of fixed-length memory cells, and each of the plurality of memory cells has a bit. When a memory reservation request is received in a memory management device that reserves / releases a memory using a bitmap that stores a bit value indicating a used / unused state of the memory cell, Means for calculating the number of required bitmap areas required to manage the size, and a required bitmap area number calculating means for calculating the number of required bitmap areas and the number of required bitmap areas calculated by the required bitmap area number calculating means. The maximum continuous free area length management procedure that compares the maximum continuous free area length of the When a bitmap search position storage means for storing the latest position in the bitmap subjected to bitmap securing operation, based on the required bitmap area number calculated by the required bitmap area number calculation means,
An empty bitmap search unit for searching for a bitmap from the latest position stored in the bitmap search position storage unit, and a bitmap for the required bitmap area number searched by the empty bitmap search unit. Bitmap securing means for securing.

Further, according to the invention described in claim 2, according to claim 1,
In the memory management device described above, the free bitmap search means includes a word unit bitmap search means for searching a bitmap in word units for a part of the required bitmap area that can be divided by a word, and the required bitmap area. A bit unit bit map search unit for searching a bit map in a bit unit for a fraction that is not divisible by a word of the number of regions, and the word unit bit map search unit based on the required number of bit map regions. It is characterized by selectively switching the bit unit bitmap search means.

[0007] According to the third aspect of the present invention, the first aspect of the present invention.
3. The memory management device according to claim 2, wherein the bitmap securing unit secures the bitmaps for the required bitmap area number, and then manipulates the bits of the bitmap to change the bitmap during use. .

Further, according to the invention described in claim 4, according to claim 1,
4. The memory management device according to any one of claims 1 to 3,
Upon receiving a memory release request, a required bitmap release area number calculating means for calculating a required bitmap area number required to manage the memory to be released, and a corresponding bitmap based on the released memory A bit map head position calculating means for calculating the head position of the bit map, and a head of the bit map calculated by the bit map head position calculating means based on the required bit map area number calculated by the required bit map release area number calculating means. Bitmap release means for changing from a position to an unused state;
A bitmap release monitoring unit that stores the position of the bitmap released by the bitmap release unit.

In the present invention, upon receiving a memory reservation request, the required bitmap reserved area number calculating means calculates the required bitmap region number required to manage the required memory size. The maximum continuous free area length management means compares the required number of bitmap areas with the maximum continuous free area length in the bitmap to determine whether or not there is a continuous free area for the required number of bitmaps. The empty bitmap search means searches for a bitmap from the latest position stored in the bitmap search position storage means based on the required number of bitmap areas. Then, the bitmap securing means secures the bitmaps for the required bitmap area number searched by the empty bitmap searching means. Therefore, it is possible to speed up the bitmap search process for memory management by determining an appropriate bitmap search start position and separating the search in word units / bit units.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. A. Configuration of Embodiment FIG. 1 is a block diagram illustrating a configuration of a memory management device according to an embodiment of the present invention. In the figure, the bitmap search speed-up method for memory management of the present invention determines an appropriate bitmap search start position, and
The bitmap search processing for memory management is speeded up by separating the search in bit units. The memory securing unit 100 receives a memory securing request. The allocated memory address calculation means 101
Calculate the memory address according to the secured bitmap. The required bitmap area number calculation means 103 calculates the number of bitmap areas required to manage the requested memory. Maximum continuous free area length management means 104
Manages the largest continuous free area in the bitmap area.

The free bitmap search means 105 searches for a free bitmap area by using two search means, word unit bitmap search means 108 and bit unit bitmap search means 109, which will be described later. . The bitmap search position notification means 106
Notify the start position of bitmap search. The bitmap securing unit 107 changes the free bitmap to a used bitmap. The word unit bitmap search unit 108 searches a bitmap in word units. The bit unit bitmap search means 109 searches a bitmap in bit units. The bitmap securing monitoring unit 110 monitors the bitmap and manages the latest position where the operation of the bitmap has been performed. The memory 111 includes an allocation area 113 and a bitmap area 112 for managing an allocation amount area.

B. Next, the operation of the embodiment of the present invention will be described in detail with reference to FIG. Here, FIGS. 2 to 5 are flowcharts for explaining the operation of the present embodiment. The memory securing means 100
Upon receiving the memory securing request, the required memory size is notified to the required bitmap area number calculating means 103. The required bitmap area number calculation means 103 calculates the number of required bitmap areas required to manage the required memory size (step S1), and returns the value to the memory securing means 100. The memory reserving unit 100 notifies the required number of bitmap areas to the maximum continuous free area length managing unit 104.

The maximum continuous free area length managing means 104 compares the required number of bitmap areas notified from the memory securing means 100 with the maximum continuous free area length in the bitmap (step S2), and determines the required number of bitmap areas. The presence / absence of a free area that can be continuously secured is notified to the memory securing unit 100. If there is no necessary free area in the bitmap, the memory securing unit 100 notifies the bitmap securing unit 107 to search another memory area. The bitmap securing unit 107 changes the empty bitmap to “in use” (step S3).

On the other hand, if there is a free area, the bitmap securing monitoring means 110 calculates the latest position in the bitmap for which the bitmap securing operation has been performed (step S4), and passes through the bitmap search position notifying means 106. To the empty bitmap search means 105. The empty bitmap search means 105 switches between the word-based bitmap search means 108 and the bit-based bitmap search means 109 according to the required number of bitmap areas, and switches from the latest position notified by the bitmap securing monitoring means 110 A map search is performed (step S5). Here, switching is performed as necessary, when the required bitmap area size exceeds one word, an empty area is searched in word units by the number of words of the required area size (step S7), and the remaining area is searched. Or, in the case of one word or less, this is for searching for an empty area in bit units (step S).
8).

Word unit bitmap search means 108
First, the quotient (the required number of words) is obtained by dividing the required number of bitmap areas by the words (step S10). Next, it is determined whether or not a necessary continuous free area (the required number of words) is found (step S11). If not found, the search target is shifted to the next word (step S12). Then, it is determined whether or not the word is unused (step S13). If not, the process returns to step S17 to search for an unused word while shifting the search target to the next word. And
When an unused word is seen, the process returns to step S16,
A continuous free area (the required number of words) is found from the word. Then, when a necessary continuous free area (the required number of words) is found, it is determined whether or not the found free area is a size divisible by words (step S).
14). If it is not divisible, that is, if there is a remainder, the process proceeds to the bit unit search process (step S15). On the other hand, if the word flag is divisible, that is, if there is no remainder, the found word flag is set in use ("1") (step S16), and the process proceeds to a memory allocation process described later (step S17).

Further, a bit unit bit map search means 1
In step 09, it is determined whether or not a necessary continuous free area (in units of bits) is found (step S20). If no continuous free area is found, the search target is shifted to the next bit (step S21). It is determined whether the bit is unused (step S22). If the bit is not unused, the process returns to step S11 to shift the search target to the next bit and search for an unused bit. When an unused bit is found, the process returns to step S10 to find a continuous free area from the bit. Then, when a necessary continuous free area is found, the found bit flag is used ("1") (step S).
23), and proceed to a memory allocation process described later (step S24).

When the necessary continuous free bitmap is found, the memory reserving means 100
7 is notified of the position of the bitmap. The bitmap securing unit 107 changes the flag of the found bitmap to “in use” (“1”) in order to secure the bitmap at the notified position, and monitors the bitmap securing monitoring unit 110 and the allocated memory address calculating unit. 10
1 is notified of the newly secured bitmap position. The bitmap securing monitoring unit 110 stores the position of the bitmap changed this time (step S31). The allocated memory address calculating means 101 calculates the allocated memory address from the notified bit map position (step S32), and returns the allocated address to the memory requester (step S33).

With the above processing, it is possible to realize a high-speed bitmap search processing for memory allocation.

C. Specific Example Next, a specific example of the present embodiment will be described in detail with reference to the drawings. Here, FIG. 6 is a conceptual diagram for explaining a specific example of the present embodiment. In the figure, a memory 600
Is composed of a bitmap area 601 and an allocation area 602. Further, it is composed of a bitmap A at the search start position and bitmaps B and C to which memories are allocated. Next, with reference to FIG. 1 and FIG. 6, a detailed description will be given of a case where a memory request in which the required bitmap is 6 bytes is made when the bitmap search start position is located at the head of the bitmap A. explain. However, each of the bitmaps A, B, and C is 1 for ease of explanation.
Word unit.

Upon receipt of the memory reservation request, the memory reservation unit 100 uses the required bitmap region number calculation unit 103 to determine the number of bitmap regions required for managing the memory of the requested size. In this case, the required number of bitmap areas is 6 bytes. The memory securing means 100 compares the maximum continuous free area length with the previously obtained 6 bytes. In this case, since the maximum continuous free area length is longer, it is determined that the memory can be secured in the bitmap area, and the processing is continued. However, if it is determined that it cannot be secured in the bitmap, a search for a memory including another bitmap is performed. The memory allocating unit 100 that has determined that the memory can be allocated by the bitmap searches the empty bitmap through the empty bitmap searching unit 105.

The free bitmap search means 105 first determines whether or not the number of necessary bitmap areas is larger than one word, and if so, finds the quotient. In this case, since the required number of bitmap areas is 6 bytes, it is larger than one word (4 bytes), the quotient of 6/4 is “1”, and the remainder is “2”. For this reason, the empty bitmap search means 105 is a word unit bitmap search means 1
At 08, a search request for a one-word continuous free area is made, and a search is made using the bit-unit bitmap search means 109 to determine whether or not there is a two-byte free area in the found area.

The operation of the word unit bitmap searching means 108 will be described in detail. One word (A) from the illustrated search start position is unused (whether it is all "0").
Check. Since the value of A is not “00000000” but “000011111”, it is not determined to be a free area, and the next one word (B) is searched. Since the value of B is “00000000”, it is determined that the area is a free area, and the processing is shifted to the bit unit bitmap search means 109 to check whether or not the remaining two bytes are used. The bit unit bitmap search means 109 outputs the following 1
The presence / absence of an empty area is checked bit by bit from the beginning of the word (C). As a result, the portion surrounded by the solid line frame shown in the drawing is determined to be a continuous 6-byte free area, and the bitmap securing means 107 is notified.

The bitmap notifying means 107 changes the previously found 6-byte free area to in use ("0000").
0000 "→" 11111111 "), the bitmap securing monitoring means 110 stores the position of the bitmap changed this time. The allocated memory address calculating means 101 having received the position of the bitmap from the bitmap securing means 107 calculates the actual memory address to be allocated from the bitmap, and returns the requested address to the memory securing requester.

D. Another Embodiment Next, another embodiment of the present invention will be described. Here, FIG. 7 is a block diagram showing a configuration of a memory management device according to another embodiment of the present invention. The other embodiment is characterized in that the bitmap search processing for memory allocation / release is further accelerated by storing the location of the bitmap area corresponding to the released allocation memory. In the figure, memory release means 700, required bitmap area number calculation means 701, maximum continuous free area length management means 702, bitmap head position calculation means 70
3, a bitmap release unit 704, a bitmap release monitoring unit 705, and a memory 706 including an allocation area 708 and a bitmap area 707 for managing the area.

Next, the operation of another embodiment of the present invention will be described in detail with reference to FIG. Upon receiving the memory release request, the memory release unit 700 uses the required bitmap region number calculation unit 701 to determine the number of bitmap areas required to manage the memory to be released. Next, the memory release means 70
0 is calculated using the bitmap head position calculation means 703.
The head position of the bitmap managing the memory is determined from the memory to be released, and the head position of the bitmap is notified to the bitmap releasing means 704. The bitmap release unit 704 changes the bitmap in the bitmap area to an unused state, and notifies the bitmap release monitoring unit 705 of the position of the bitmap.
The bitmap release monitoring unit 705 stores the position of the notified bitmap.

When the release of the area is completed, the memory release means 700 notifies the maximum continuous free area length management means 702 of the previously obtained bitmap number. The maximum continuous free area length managing means 702 compares the current maximum continuous free area length with the notified bitmap number, and when the notified bitmap, that is, the just released bitmap number, is larger. Store that value.

As a result, it is possible to further speed up the bitmap search processing for memory allocation / release.

[0028]

As described above, according to the present invention,
In the bitmap search process for searching for a free area of the bitmap for managing the memory, notice that there is a high possibility that an area of the required size is vacant near the place where the bitmap operation was performed immediately before. And start the search from the place where you just performed the bitmap operation,
If the required bitmap size is one word or more, since the search is performed in word units, there is an advantage that the bitmap search process for memory allocation can be speeded up.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a memory management device for realizing a high-speed bitmap search method according to an embodiment of the present invention.

FIG. 2 is a flowchart for explaining the operation of the present embodiment.

FIG. 3 is a flowchart for explaining the operation of the present embodiment.

FIG. 4 is a flowchart for explaining the operation of the present embodiment.

FIG. 5 is a flowchart for explaining the operation of the present embodiment.

FIG. 6 is a conceptual diagram for explaining a specific operation.

FIG. 7 is a block diagram showing a configuration of a memory management device for realizing a high speed bitmap search method according to another embodiment of the present invention.

[Explanation of symbols]

Reference Signs List 100 memory securing means 101 allocated memory address calculating means 103 necessary bitmap area number calculating means (necessary bitmap securing area number calculating means) 104 maximum continuous free area length managing means 105 free bitmap searching means 106 bitmap searching position notifying means ( Bitmap search position storage means) 107 Bitmap securing means 108 Word unit bitmap search means 109 Bit unit bitmap search means 110 Bitmap reservation monitoring means (Bitmap search position storage means) 600 Memory A 601 Bitmap 602 Allocation area 700 memory release means 701 required bitmap area number calculation means (necessary bitmap release area number calculation means) 702 maximum continuous free area length management means 703 bitmap head position calculation means 704 bits -Up release means 705 bitmap release monitoring means 706 memory 707 bitmap area 708 assigned area

Claims (4)

[Claims] 1. A memory part is divided into a plurality of fixed-length memory cells, and a bit is assigned to each of the plurality of memory cells, and is stored as a bit value indicating a used / unused state of the memory cell. In a memory management device that allocates / releases memory using a bitmap to be allocated, when a memory allocation request is received, a required bitmap area required to manage the required memory size is calculated. Comparing the required bitmap area number calculated by the required bitmap securing area number calculating means with the maximum continuous free area length in the bitmap, there is a free area continuous by the required bitmap number. Means for managing the maximum continuous free area length for determining whether or not the bit is the latest position in the bitmap for which the bitmap securing operation has been performed. Based on the number of required bitmap areas calculated by the required number of bitmap areas calculated by the required bitmap area number calculating means, and performs a search for a bitmap from the latest position stored in the bitmap search position storage means. A memory management device comprising: a bitmap search unit; and a bitmap securing unit that secures bitmaps for the required number of bitmap areas searched by the empty bitmap search unit. 2. An empty bitmap search unit, comprising: a word-unit bitmap search unit for searching a bitmap in word units for a portion of the required bitmap region that is divisible by a word; A bitmap search unit for searching a bitmap in bit units for a fraction that is not divisible by a word, wherein the word unit bitmap search unit and the bit are searched based on the required number of bitmap areas. 2. The memory management device according to claim 1, wherein the memory management device selectively switches between unit bitmap search means. 3. The bitmap securing means, after securing bitmaps for the required bitmap area number, manipulates bits of the bitmap to change the bitmap during use. 3. The memory management device according to 2. 4. Upon receiving a memory release request, a required bitmap release area number calculating means for calculating a required bitmap area number required to manage the memory to be released; and A bitmap head position calculating means for calculating a head position of a corresponding bitmap; and a required bitmap area number calculated by the required bitmap release area number calculating means. Bitmap releasing means for changing from the head position of the bitmap to an unused state, and bitmap release monitoring means for storing the position of the bitmap released by the bitmap releasing means. The memory management device according to claim 1.