CN103593300B - Memory allocating and collecting method - Google Patents

Abstract

The invention provides a method for memory allocation and recovery. The system includes three parts: a segmented statistics module (1), a control configuration module (2), and a selection algorithm module (3). The three parts work together to complete system memory allocation and recovery, wherein : In the segmentation statistics module (1), according to the segmentation granularity, the memory pages in the memory statistics range are segmented and counted. For a continuous memory page, when the statistical value is updated, the pages are allocated and recycled respectively. The number of times, record the allocation and recovery times of this segment of memory. The upper limit of the number of times should be the maximum integer that the system can save. The statistical value will be cleared to zero after the statistical value of allocation or recovery is referenced as a decision parameter. The method is to address the characteristics of relatively abundant hardware resources and complex application requests, and propose a new memory allocation and recovery mechanism, which is different from the mechanism used by the previous operating system, and is more in line with the characteristics of modern computers and more suitable for the behavior of modern applications. need.

Description

A method of memory allocation and recovery

technical field

The invention relates to the technical field of computer applications, in particular to a memory allocation and recovery method.

Background technique

As the core software of the system, the operating system manages the physical resources of the machine and maintains them in a normal state; at the same time, it responds to various requests from user programs and system hardware with these resources. The operating system must ensure that these requests are responded to in a timely and correct manner so that the entire system can function normally.

Among the hardware physical resources managed by the operating system, memory is an indispensable and important component. The operating system needs to properly initialize and manage all memory resources, and handle memory usage requests from various programs, including the operating system itself. It is also necessary to reclaim the memory when the program exits or no longer needs a certain memory segment, and reintroduce it into the free memory to ensure that the next memory usage request will be satisfied.

In the early days of information technology when physical resources were still scarce, it was very important to reclaim and recycle limited memory in time to complete a large amount of work. It expanded the performance of the machine and maximized the potential of existing physical resources, showing that The charm of software. With the continuous advancement of many technologies such as mechanical materials and electronics, the physical resources on modern computers are relatively abundant, but a reasonable management mechanism is still needed to manage these resources. Because technological progress has also brought about a huge expansion of the amount of information, the volume of data that modern computers need to process and the complexity of algorithms have also increased geometrically, which also puts forward higher requirements for the software on modern computers, especially is the operating system.

As far as memory management is concerned, there are a large number of possible physical resources on the one hand, and a large number of complex processing requests on the other. In the middle, a very good mechanism is needed to manage and unblock them, so as to ensure the full utilization of physical resources and the timely satisfaction of program requests. Normal operation, further under extreme pressure conditions, can fully tap the potential of the hardware and play its due performance. In the memory management system, the memory allocation and recovery mechanism is an important part. It is mainly used to handle memory allocation requests of applications and system programs, and subsequent memory recovery to ensure sufficient memory to meet subsequent requests.

In the existing operating systems, most of the memory management mechanisms have a history of more than ten years, evolved from algorithms that manage relatively small system memory, and may not be applicable to current application hardware scenarios. Aiming at the characteristics of relatively abundant hardware resources and complicated application program requests, the present invention proposes a new memory allocation and recycling mechanism, which is different from the mechanism used by previous operating systems, and is more in line with the characteristics of modern computers and more suitable for the behavior of modern application programs. need.

Contents of the invention

The purpose of the present invention is to provide a memory allocation recovery method.

The purpose of the present invention is achieved in the following manner, the system includes a segmented statistics module (1), a control configuration module (2), three parts of the selection algorithm module (3), and the three parts cooperate to complete system memory distribution and reclaiming, in:

In the segment statistics module (1), segment statistics are performed on the memory pages in the memory statistics range according to the segment granularity. For a continuous segment of memory pages, when the statistical value is updated, statistics are made on which pages are allocated and reclaimed. Number of times, which records the number of allocations and reclaims of this segment of memory. The upper limit of the number of times should be the maximum integer that the system can save. The statistical value will be cleared to zero after the statistical value of allocation or reclaiming is referenced as a decision parameter. :

Segmentation granularity refers to the size of each segment of memory when segmenting the memory. The unit is a physical memory page. The minimum granularity is 1 page, and the maximum granularity depends on the size of the system memory;

The memory statistics range refers to the memory range for segmented statistics. Not all the memory in the system is in the statistics range. Among all the memory pages used for allocation and recovery, excluding the memory pages occupied by the operating system itself and some libraries, they should be included in the statistics. range, because the memory occupied by the operating system itself and the library will always reside in the memory and will be used throughout the life cycle of the system operation, so it does not need to be included in the statistical scope for allocation and recovery control;

The time to update the statistical value is when a page in a segment of memory is allocated or reclaimed, and the statistical data of the segment of memory is updated in the interface;

Statistical clearing refers to the clearing of statistical values of allocation and recycling. After the statistical value of allocation or recycling is referenced as a decision parameter, it is cleared to ensure that the statistics describe the recent memory usage in the system, or in Control configuration module (2) configures whether to carry out clearing operation, if not carrying out clearing operation, then what statistical data described is the historical accumulation information of system memory use;

The control configuration module (2) controls the attributes in the method to coordinate the completion of the entire allocation and recovery method. These configurations are changed by the system administrator to make this method more suitable for the use environment. The controlled configuration in the method has a segmented granularity , Distribution Tendency, Recycling Strength, Recycling Tendency, and Statistical Clearing. Among them:

Allocation tendency refers to the tendency to select memory segments when allocating memory: whether to reuse them, if not to reuse them, each time you select, you will not select memory segments that already have allocation statistics. If all statistical memory segments are If it has already been used, it will trigger statistics clearing;

Recycling strength refers to the strength of reclaiming memory, the greater the strength, the more memory the recycling program reclaims;

Recycling tendency refers to the tendency to select memory segments when reclaiming memory: under the tendency of least recently used and least used in history, the recycling program will give priority to reclaiming the memory segment with the least allocation count in the statistical information. Statistics are required for this tendency Clear; under the trend of least usage in history, the behavior of the recycling program is the same, but the statistics are not cleared;

Selection algorithm module (3). The selection algorithm module includes allocation selection algorithm and recovery selection algorithm. When allocation or recovery, the best memory segment is selected according to the statistical information obtained by the segmentation statistics module (1), and the actual memory segment is selected. Allocation recycling, where:

Allocation selection algorithm, when selecting a memory segment for allocation operation, according to the statistical information, avoid the memory segment with a higher count of allocation and recovery, and select the memory segment with a lower statistical count; combined with the allocation tendency, decide whether to reuse the memory segment to select Used or not memory segment;

Recycling selection algorithm. When selecting memory segments for recycling operations, according to statistical information, select memory segments with statistical counts ranging from small to large for recycling operations. Combined with recycling efforts, if you need to continue recycling, select memory segments with larger statistical counts to continue recycling operate;

The specific allocation and recovery steps are as follows:

Step 1: In the initialization stage of the system, when the memory is initialized, the segmentation statistics module (1) divides the memory used by the system for allocation and recovery into equal segments in units of pages, each segment is 8 pages in size, and the system divides a total of 512 segments ;

Step 2: Establish a statistical data pool, two arrays of the largest integer type, alloc[512] records the number of allocations that occur in each memory segment, reclaim[512] records the number of reclaims that occur in each memory segment, and the initial value is 0 ;

Step 3: During the startup and operation of the system, each time the memory allocation and recovery occurs, the alloc and reclaim arrays are updated;

Step 4: Read the configuration, the statistical data needs to be cleared, the allocation tendency is not reused, the recovery is strong, and the corresponding recycling tendency is the least recently used, and the control configuration is allowed to be modified by the system administrator at any time;

Step 5: After the system is running, the memory allocation request for the system process and the application process is controlled by the configuration module (2) Check the values of the alloc and reclaim arrays according to the content of the configuration control, and in the memory segment that can be allocated (alloc[i] ==reclaim[i]), find the memory that has not been allocated, that is, the memory segment corresponding to alloc[i]==0, and perform specific allocation actions;

Step 6: If the memory allocation in this segment is successful, select the algorithm module (3) to update the alloc array, and add 1 to the count in the corresponding segment;

Step 7: According to the configuration control, the recovery intensity is high, and the selection algorithm module (3) will start at an appropriate time. According to the configuration, check the values of the alloc and reclaim arrays, and in the segment that can be recycled (alloc[i]>reclaim[ i]), look for the corresponding segment with a smaller value of alloc[i] to perform specific recovery operations;

Step 8: If the memory in this segment is recovered successfully, update the reclaim array;

Step 9: After all memory segments have been used, or when the clearing time interval value arrives, clear the alloc and reclaim arrays;

Step 10: When the system is shut down, after the shutdown process exits, the occupied system resources are released.

The beneficial effects of the present invention are: the present invention proposes a new type of memory allocation and recovery mechanism, which is different from the mechanism used by previous operating systems, and is more in line with the characteristics of modern computers and more For the behavioral needs of modern applications.

Description of drawings

Figure 1 is a schematic diagram of the segmented statistical structure;

Figure 2 is a schematic diagram of the operation of the implemented mechanism.

detailed description

The method of the present invention is described in detail below with reference to the accompanying drawings.

In order to make the object, technical solution and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described here are only used to explain the present invention, not to limit the present invention.

Referring to the accompanying drawings, a specific example will be used to describe the process of realizing this mechanism for the content of the present invention.

As described in the summary of the invention, the system structure of the present invention mainly includes: a segmentation statistics module, a configuration control module and a selection algorithm module, and the specific allocation and recovery steps are as follows:

Step 1: In the initialization stage of the system, when the memory is initialized, the segmentation statistics module (1) divides the memory used by the system for allocation and recovery into equal segments in units of pages, each segment is 8 pages in size, and the system divides a total of 512 segments ;

Step 2: Establish a statistical data pool, two arrays of the largest integer type, alloc[512] records the number of allocations that occur in each memory segment, reclaim[512] records the number of reclaims that occur in each memory segment, and the initial value is 0 ;

Step 3: During the startup and operation of the system, each time the memory allocation and recovery occurs, the alloc and reclaim arrays are updated;

Step 4: Read the configuration, the statistical data needs to be cleared, the allocation tendency is not reused, the recovery is strong, and the corresponding recycling tendency is the least recently used, and the control configuration is allowed to be modified by the system administrator at any time;

Step 5: After the system is running, the memory allocation request for the system process and the application process is controlled by the configuration module (2) Check the values of the alloc and reclaim arrays according to the content of the configuration control, and in the memory segment that can be allocated (alloc[i] ==reclaim[i]), find the memory that has not been allocated, that is, the memory segment corresponding to alloc[i]==0, and perform specific allocation actions;

Step 6: If the memory allocation in this segment is successful, select the algorithm module (3) to update the alloc array, and add 1 to the count in the corresponding segment;

Step 7: According to the configuration control, the recovery intensity is high, and the selection algorithm module (3) will start at an appropriate time. According to the configuration, check the values of the alloc and reclaim arrays, and in the segment that can be recycled (alloc[i]>reclaim[ i]), look for the corresponding segment with a smaller value of alloc[i] to perform specific recovery operations;

Step 8: If the memory in this segment is recovered successfully, update the reclaim array;

Step 9: After all memory segments have been used, or when the clearing time interval value arrives, clear the alloc and reclaim arrays;

Step 10: When the system is shut down, after the shutdown process exits, the occupied system resources are released.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present invention shall be included in the protection of the present invention. within range.

Except for the technical features described in the instructions, all are known technologies by those skilled in the art.

Claims (1)

1. a kind of Memory Allocation recovery system, it is characterised in that, 2) control configuration module, selects including segmentation statistical module 1) Algoritic module 3), three parts, three part collaborative work completion system Memory Allocations and recovery, wherein：

In segmentation statistical module 1）In, according to segmentation granularity, segmentation statistics is carried out to the page of internal memory scope of statistics, for one The continuous page of section, on the opportunity that statistical value updates, counts the number of times that wherein page is allocated and reclaims respectively, is designated as in this section Deposit distribution, the recovered frequency of generation, the upper limit of secondary numerical value should be the maximum integer that system can be preserved, statistical value in distribution or Reclaim statistical value to be cited as after decision parameters, can be reset by statistics, wherein：

Segmentation granularity, refer to internally deposit into row segmentation when, the size of every section of internal memory, unit are physical memory page, and minimum particle size is 1 Page, maximum particle size depend on Installed System Memory size；

Memory statistics scope, be carry out be segmented statistics memory range, be not all internal memories of system all in scope of statistics, in institute Have for being allocated back in the page received, remove the page that operating system itself and some storehouses take, should all include statistics Scope, the internal memory that operating system itself and storehouse take can be resided in internal memory always, the meeting in the life cycle of system operation Used always, do not include scope of statistics and be allocated recovery control；

On the opportunity that statistical value updates, be to work as to have page to be allocated or reclaim in one section of internal memory, in the interface the system to this section of internal memory Count and be updated；

Statistics clearing, refers to distribution and the clearing of the statistical value for reclaiming, and is cited as decision-making ginseng distributing or reclaiming statistical value After number, reset to ensure that statistical data describes the service condition of nearest Memory System, or in control configuration module 2) this is configured in and whether is zeroed out operation, if not being zeroed out operation, statistical data is described in system Deposit the history cumulative information for using；

Control configuration module 2）, the attribute in method is controlled, completes entirely to distribute recovery method to cooperate with, these configurations Changed by system manager so that this method is more applicable for use environment, in method, had segmentation granularity by what control was configured, point With tendency, tendency is reclaimed, statistics resets several parts, wherein：

Distribution tendency, is that, in storage allocation, the selection to application heap is inclined to：Whether reuse, if do not reused, Would not select to distribute the application heap of statistical counting when selection every time, if all statistics application heaps have all made Used, then triggering statistics resets；

Recovery ability, is the size of the ability when internal memory is reclaimed, and ability is bigger, and reclaimer reclaims more internal memories；

Tendency is reclaimed, is that, when internal memory is reclaimed, the selection to application heap is inclined to, reclaimer can preferentially to distributing in statistical information Counting minimum application heap carries out reclaimer operation；

Selection algorithm module 3）, selection algorithm module includes distributing selection algorithm and reclaims selection algorithm, in distribution or recovery, Respectively according to segmentation statistical module 1) obtained by statistical information, select optimal application heap, carry out physical memory distribution and reclaim, Wherein：

Distribution selection algorithm, when selecting application heap to be allocated operation, according to statistical information, avoids distribution recovery and counts higher Application heap, select the relatively low application heap of statistical counting；With reference to distribution tendency, decide whether to reuse application heap, to select Used whether application heap；

Selection algorithm is reclaimed, when selecting application heap to carry out reclaimer operation, according to statistical information, selects statistical counting ascending Application heap carry out reclaimer operation, if it need to continue to reclaim, select the bigger application heap of statistical counting to continue reclaimer operation；

Concrete distribution recycling step is as follows：

Step 1：In the system start-up initialisation stage, during internal memory initialization, 1) system is used to distribute recovery by segmentation statistical module Internal memory be averagely segmented for unit according to page, every section of size is page 8, and system has been divided into out 512 sections；

Step 2：Statistical data pond is set up, the array of two maximum integer types, alloc [512] are sent out in recording every section of application heap Raw distribution number of times, the recovered frequency that reclaim [512] occurs in recording every section of internal memory, initial value are set to 0；

Step 3：During system start-up runs, each Memory Allocation is reclaimed to be occurred, and all updates alloc and reclaim numbers Group；

Step 4：Configuration is read, statistical data needs to reset, and distribution tendency reclaims great efforts not reuse, and reclaims tendency It is corresponding then for least recently used, control configuration allows to be changed by system manager at any time；

Step 5：After system operation is got up, the request to system process and application process storage allocation controls configuration module 2） According to configuration control content, check the value of alloc and reclaim arrays, the application heap alloc [i] that can distribute== In reclaim [i], the internal memory also not distributed is found, i.e. it is dynamic that alloc [i]==0 corresponding application heap carries out specific distribution Make；

Step 6：Such as in this section of Memory Allocation success, 3) selection algorithm module updates alloc arrays, and in correspondent section, count is incremented；

Step 7：According to configuration control, the dynamics of recovery is big, and 3) selection algorithm module can be in due course startup, according to matching somebody with somebody Put, check the value of alloc and reclaim arrays, in section alloc [i] that can be reclaimed>In reclaim [i], find The less correspondence section of alloc [i] value carries out specific reclaimer operation；

Step 8：Such as in this section of Memory recycle success, reclaim arrays are updated；

Step 9：After all application heaps were all used, or when resetting time interval value arrival, to alloc and reclaim numbers Group is zeroed out operation；

Step 10：During system closedown, after shutdown process is exited, the system resource of release busy.