Discrete Distribution of memory

Source: Internet
Author: User
(1) Paging storage management refers to dividing the address space of a process into several equal parts, called pages or pages. Correspondingly, divides the memory space into several blocks of the same size as the page. These are called (physical) blocks or page boxes. When allocating memory for a process, load several pages in a process into non-adjacent physical blocks discretely. ---- This is called discretization. (2) because the page size is generally a power byte of 2; generally, it is between B and 4 kb. After the memory space is divided, there is no "external fragment". Because each physical block can be allocated to a page of the Process discretely, the number of remaining physical blocks cannot meet the requirements of a process. On average, the system generates "Page fragments" in the middle of the night. From this, the paging Storage Management solves the "fragmentation problem "; improves the memory utilization. Pure paging storage management means that all pages of a process can be loaded into the physical blocks of the memory for operation. (3) Address structure of the paging system; it consists of two parts: page number P and page displacement W, that is, the address on the page;

(3) continuous allocation forms many "fragments". To reduce fragments and improve memory utilization, the discrete allocation mode is introduced;

(4) paging system memory management: the system address is changed by querying the page table;

(5)

(6) It indicates the address conversion mechanism of the paging system. The address conversion mechanism is completed by hardware, including automatic searching for Memory Page tables;


(7) The basic task of the address translation organization is to use the hardware to query the page table and ProgramThe logical address in is changed to the physical address in the memory. To implement the address conversion function, set the page table register in the system to store the table's start address and page table length. when the process is not executed, the start address and length of the page table corresponding to each process are stored in the PCB of the process. When the process is scheduled, it is loaded into the page table register. (8) segment address converter;

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