JPH04314147A - Memory managing system - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a memory management scheme in an operating system.

0002

[Prior Art] Memory allocation methods in conventional memory management systems either do not have the concept of pools for storing free memory, or even if there is a concept of pools, memory is allocated from each pool regardless of the priority of the task. Therefore, if a low priority task allocates a large amount of memory, even if a high priority task allocates memory,
There were cases where memory could not be allocated and operation could not be performed.

[0003] On the other hand, the memory in the system is defined as free memory,
Even if you set up a pool that specifies the lowest priority of tasks that can be secured as spare memory when there is a memory shortage, when there is a shortage of free memory, memory will be secured preferentially from a pool with a lower priority, so the load will not be as high. Even without this, there was a problem that memory could not be secured from normal low-priority tasks.

0004

SUMMARY OF THE INVENTION In the above-described conventional system, memory reservation was permitted regardless of the priority of the task, which caused the following problems.

(1) If a low-priority task allocates a large amount of memory, even a high-priority task may be unable to allocate memory and become unable to operate. It also puts pressure on the memory of the entire system.

(2) In order to avoid the above problem, if the memory is divided and managed as a dedicated memory and used only for an arbitrary task, a certain amount of margin is secured, resulting in a large amount of division loss.

(3) Even if a pool is provided that specifies the lowest priority of tasks that can be secured as free memory in the system and as spare memory in case of memory shortage, when there is a shortage of free memory, data will be transferred from the low priority pool. Since memory is allocated preferentially, there is also the problem that memory cannot be allocated from normal low-priority tasks even if the load is not very high.

[0008]

[Means for Solving the Problems] According to the present invention, a real memory pool dividing means divides memory in a system into arbitrary amounts as pools and holds management information of the pools;
Memory pool priority setting means adds a lowest priority to a task that is permitted to allocate memory from the memory pool, and queues pool management information in an ascending order in a pool management information queue; , a real memory pool selection means that selects a usable pool based on the priority of the invoking task, and when memory cannot be secured from the memory pool corresponding to the priority due to memory shortage, low memory pool is selected from the memory pool corresponding to the priority of the source task. On the priority side, there is a memory search means that searches for a free memory pool and secures memory from that pool, and if the memory search means cannot secure memory, the issuing task is sent to the waiting queue of the pool corresponding to the priority. When memory is released, it searches for pool free tasks from the highest priority pool to the priority pool corresponding to the freed memory, and searches among the pool free tasks. ,
A "memory management system using a prioritized memory pool" is obtained, which is characterized by having an idle waiting release means for giving memory to a pool idle task with the highest priority.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an embodiment of the present invention will be described in more detail with reference to the drawings.

Referring to FIG. 1, one embodiment of the present invention includes:
Memory management method 10 using prioritized memory pool, lowest priority of allocable tasks 21, and pool free queue 22
a pool management information 20 that manages information about the created memory pool, and a pool management information queue 30;
The task consists of a memory securing task 40 and a pool waiting task 50.

The memory management method 10 using prioritized memory pools includes a real memory pool dividing means 11 that divides the memory in the system into arbitrary amounts of pools and holds management information of the pools, and a memory management system 10 that divides the memory in the system into arbitrary amounts as pools. A memory pool priority setting means 12 adds the lowest priority of the task to which reservation is permitted and queues the pool management information 20 in ascending order in the pool management information queue 30; A real memory pool selection means 13 that selects a usable pool based on priority, and when memory cannot be secured from a memory pool corresponding to the priority due to memory shortage, a memory pool with a lower priority than a memory pool corresponding to the priority of the securing source task is provided. On the other hand, there is a memory search means 14 that searches for a free memory pool and secures memory from that pool, and if the memory search means 14 cannot secure memory, it places a pool corresponding to the priority of the issuing task in a waiting queue. A pool free waiting means 15 that queues tasks and puts them in a waiting state, and when memory is released, searches for pool free waiting tasks from the highest priority pool to a priority pool corresponding to the released memory, and searches for pool free waiting tasks among the pool open waiting tasks. , and a pool idle waiting release means 16 that provides memory to the pool idle task with the highest priority.

Next, with reference to FIG. 2, the operation when the pool management information 20 and the memory reservation task 40 secure memory in this embodiment and encounter a memory shortage will be described in detail. In addition, in the figure, the priority indicates that the smaller the value, the higher the priority.

FIG. 2(1) shows pool management information 20 in a state where three memory pools with different pool priorities 21 have been created.
In this state, when the memory allocation task 40 with priority "4" allocates memory, the real memory pool selection means 13 selects a memory allocation corresponding to the priority of the own task from among the memory pools in the system. The pool with the lowest possible task priority of 21 is selected. In this example, since the same priority pool is not defined, the memory search means 14 checks the pool with priority "5", which is lower than the priority of the own task, and secures memory. If there is no free memory in the memory pool with priority "5", then the pool with lower priority is further checked. FIG. 2(2) shows the memory test range in this example. If there is no free memory even after checking all the memory pools that can be secured, the pool free waiting means 15 stores the memory securing task 40 in the pool free waiting queue 22 of the pool management information 20 with a priority corresponding to the priority of the memory securing task. queue. In this example, since pool management information 20 with priority "4" does not exist, the pool management information 20 with priority "5", which is the highest priority among the pools that can be secured, is queued. This state is shown in FIG. 2(3). In this example, the priority of the memory allocation task 40 is "
4", therefore memory cannot be secured even if there is space in the pool with priority "3". Furthermore, after the memory is released, the pool free standby release means 16 uses the pool management information 2.
The 0 pool idle queues 22 are checked in order from the highest priority, and if a pool idle task 50 exists, that task is released from the waiting state. In FIG. 2 (3), when memory is released to the pool with priority "7", the pool with priority "3" is inspected and the pool free queue 22 with priority "5" is checked.
The pool idle task 50 queued in the queue is released from waiting. Furthermore, in a similar situation, if memory with a priority level of "3" is released, the waiting state of the pool free task 50 queued in the pool free queue 22 with a availability level of "5" will not be released. . As described above, pool priority 21 limits the tasks that use the memory stored in the pool, resulting in memory pressure in the system due to large amounts of memory being reserved for low-priority tasks, and processing stagnation for high-priority tasks. can be prevented.

[0014]

Effects of the Invention As explained above, the present invention divides the real memory in the system into several parts and assigns the lowest priority to tasks that are allowed to allocate memory from that memory. In some cases, it becomes possible to limit the amount of memory that can be secured depending on the priority of the source task, resulting in memory pressure in the system due to large amounts of memory being secured by low-priority tasks, and processing problems due to the inability of high-priority tasks to secure memory. Without stagnation or slowing down the processing of low-priority tasks,
It can be prevented.

[Brief explanation of drawings]

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

FIG. 2 is a diagram for explaining the operation of the embodiment shown in FIG. 1;

[Explanation of symbols]

10 Memory management method using prioritized memory pool 11 Real memory pool dividing means 12 Memory pool priority setting means 13
Real memory pool selection means 14 Memory search means 15 Pool free waiting means 16 Pool free waiting release means 20 Pool management information 21 Lowest priority of allocable tasks 22 Pool free queue 30 Pool management information queue 40 Memory reservation task 50 Pool free waiting task

Claims (1)

[Claims] Claim 1: A real memory pool dividing means that divides the memory in the system into arbitrary amounts as pools and holds management information of the pool, and a minimum priority of a task that is allowed to secure memory from the memory pool is added. and a memory pool priority setting means for queuing pool management information in an ascending order in a pool management information queue, and a real memory pool selection means for selecting an available pool based on the invoking task priority from divided pools when securing memory. If the memory cannot be secured from the memory pool corresponding to the priority due to insufficient memory,
A memory search means that searches for a free memory pool from the memory pool corresponding to the priority of the securing source task to the lower priority side and secures memory from that pool, and when the memory search means cannot also secure memory, A pool free waiting means that queues the issuing task in the waiting queue of the pool corresponding to the priority and puts the task in the waiting state, and when memory is released, the pool is pooled from the highest priority pool to the priority pool corresponding to the released memory. 1. A memory management method using a prioritized memory pool, characterized in that it has an idle release means that searches for an idle task and gives memory to a pool idle task with the highest priority among the pool idle tasks.