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Memory Proportioned Pages

IP.com Disclosure Number: IPCOM000079516D
Original Publication Date: 1973-Jul-01
Included in the Prior Art Database: 2005-Feb-26
Document File: 2 page(s) / 42K

Publishing Venue

IBM

Related People

Miller, TH: AUTHOR

Abstract

Memory proportioned pages will enhance paging efficiency on a Virtual Memory Machine. By having the same efficient range (64 to 128) of pages, the paging algorithm is simpler and does not have to change as pageable memory size changes. As pages get larger on larger memories, more of a given task will be paged in and out in approximately the same time as a smaller page can be paged in or out. Efficient use of this feature requires the supervisor program to be aware and take advantage of the algorithm when assigning virtual addresses.

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Memory Proportioned Pages

Memory proportioned pages will enhance paging efficiency on a Virtual Memory Machine. By having the same efficient range (64 to 128) of pages, the paging algorithm is simpler and does not have to change as pageable memory size changes. As pages get larger on larger memories, more of a given task will be paged in and out in approximately the same time as a smaller page can be paged in or out. Efficient use of this feature requires the supervisor program to be aware and take advantage of the algorithm when assigning virtual addresses.

Implementation of memory proportioned pages uses the track format shown in Fig. 1. The number of sectors transferred from the file on a given page command is dependent on the page size. The page size is, in turn, determined by the memory size. Only one page description is transferred for a page, independent of the page size.

The page size is variable depending on what size of pageable memory is installed. The page size is not dependent on file configuration. The files are formatted with 256 bytes of data and a 12-byte page description on each sector. A given command, transfers data equal to the page size and the 12-byte page description from the last 256-byte sector of that page. The 12-byte page description is transferred into a disjointed memory location from the real memory page location. This operation for a 128K memory is depicted in Fig. 2. Thus, on all data operations 12 plus the page size bytes of dat...