SNHU Computer Science Shared Memory Pages Discussion:
Shared memory pages are an example of a topic where a picture is worth a thousand words. Find at least one illustration in Google Images by entering the search key "shared memory pages" in the search box. Be sure to enter it in the search box with quotes so the entire phrase is interpreted by the search engine as a single string.
Using an illustration you find, make that picture the focus of your post. Create a Discussion Topic post that outlines the function of shared memory pages. Go into detail about the proper operation of shared memory pages as described by the course textbook. If you find an illustration that does not agree with the course textbook, be sure to use it and make any inconsistencies the focus of your post.
Peers:
Peer Review #1Jesse Edwards postedAt any given time, multiple users may be running the same program at the same time, or one user may be running multiple programs that use the same library. To accomplish this efficiently, the pages can be shared to prevent duplicate pages from simultaneously being in memory. Each process can be given its own page table that points to the same pages, and the pages will be mapped as read only. If one of the programs writes to the page, it causes a trap to the OS which then creates a copy of the updated page giving each processes its own copy. At this point, both copies will be read/write allowing the processes to proceed without further trapping. ReferencesAbraham Silberschatz, Greg Gagne, and Peter Baer Galvin, "Operating System Concepts, Ninth Edition "Galvin, Peter, Gagne, Greg, Silberschatz, Abraham (2013). OPERATING SYSTEM CONCEPTS (Ninth ed.). Danvers, MA: John Wiley & SonsTanenbaum, A. S., & Bos, H. (2015). MODERN OPERATING SYSTEMS (Fourth ed.). Upper Saddle River, NJ: Pearson Education, Inc.
Peer Review #2Benicia Curtis posted A shared memory page is when virtual memory in an application has data that is housed in a library or database and has sharable options. Through memory management units, the libraries are mapped appropriately depending on memory sizing. In the illustrated example, the virtual memory, left side, has a shared library. Within the shared library there are multiple pages that will be shared from the parent(original) to the child (copy). The shared pages go through the memory management unit to determine where the memory will be saved on the physical address.In comparison from the illustration to the text, the text is more detailed about shared pages and libraries regarding operating system processing to have one copy of the data pages. “If a program is started up twice, most operating systems will automatically share all the text pages so that only one copy is in memory. Depending on the operating system, each process may get its own private copy of the data pages, or they may be shared and marked read only.” (Tanenbaum & Bos) In comparison to the illustration, it is assumed that all pages from the program can be shared multiple times from the program. In actuality, the shared pages are read only, each process will get its own private copy, and it will only be copied once. Tanenbaum, A. S., & Bos, H. (2017). Modern operating systems. Vancouver, B.C.: Langara College.Silberschatz, A., Gagne, G., & Galvin, P. B. (n.d.). Virtual Memory. Retrieved February 17, 2020, from https://www.cs.uic.edu/~jbell/CourseNotes/Operatin...