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Decrease Memory Usage by Immediately Freeing the Not Required Pages

IP.com Disclosure Number: IPCOM000016169D
Original Publication Date: 2002-Jul-13
Included in the Prior Art Database: 2003-Jun-21
Document File: 2 page(s) / 41K

Publishing Venue

IBM

Abstract

Disclosed is the concept of reducing memory usage and also in distributing the I/O. Virtual memory manager (VMM) extends the logical address space by using part of the available secondary storage (such as hard disk etc.) to hold portions of the application and data that are not currently in physical memory. When an application needs to operate on a portion of memory that has been transferred to disk, the virtual memory manager loads this portion back into the physical memory. Virtual memory manager handles memory in a unit, which is called page (different systems have different page sizes) which generally are 4K. Whenever an application runs it requires memory. Memory is provided to the application from the logical pool as discussed above. These pages are kept in the memory (or in use and they are replaced from the memory using below given logic: 1) page has not been used for long time (it will be replaced by some demon according to page replacement algorithm), 2) above demon will be triggered if system falls low on memory. In order to free the page (memory) an I/O (if page has changed is started on them and whenever I/O is over the page (memory) becomes available.

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Decrease Memory Usage by Immediately Freeing the Not Required Pages

Disclosed is the concept of reducing memory usage and also in distributing the I/O. Virtual memory manager (VMM) extends the logical address space by using part of the available secondary storage (such as hard disk etc.) to hold portions of the application and data that are not currently in physical memory. When an application needs to operate on a portion of memory that has been transferred to disk, the virtual memory manager loads this portion back into the physical memory. Virtual memory manager handles memory in a unit, which is called page (different systems have different page sizes) which generally are 4K. Whenever an application runs it requires memory. Memory is provided to the application from the logical pool as discussed above. These pages are kept in the memory (or in use ) and they are replaced from the memory using below given logic: 1) page has not been used for long time (it will be replaced by some demon according to page replacement algorithm), 2) above demon will be triggered if system falls low on memory. In order to free the page (memory) an I/O (if page has changed ) is started on them and whenever I/O is over the page (memory) becomes available.

As shown above, page replacement is guided according to the memory demand and allows the unwanted pages (pages which can be freed ) to be in memory until the page replacement demon free those pages. The page replacement demon generally frees pages in group and due to which I/O's are not distributed and these unwanted pages (pages which could have been freed earlier ) add to the I/O. If we free these pages it wil...