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Topic: Demand paged

	Avoidance of deadlocks in a demand paged video adapter - Patent 5592670
		As the memory is demand paged, a potential for a deadlock arises.
		The page frame 50 is used in conjunction with an offset 52 (which is equal to offset 38 of the linear address 30) to produce the physical address 32.
		Further suppose that the source page and destination page are different, and additionally suppose that, initially, the page holding the source address is not present in the page frame 68 (i.e., page frame 0) of physical memory 58.
	www.freepatentsonline.com /5592670.html (5016 words)

	DEMAND PAGING - Definition
		A kind of virtual memory where a page of memory will be paged in if an attempt is made to access it and it is not already present in main memory.
		This normally involves a memory management unit which looks up the virtual address in a page map to see if it is paged in.
		If it is not then the operating system will page it in, update the page map and restart the failed access.
	www.hyperdictionary.com /dictionary/demand+paging (199 words)

	Demand paging - Computing Reference - eLook.org (Site not responding. Last check: 2007-10-09)
		A kind of virtual memory where a page of memory will be paged in if an attempt is made to access it and it is not already present in main memory.
		Paging in a page may first require some other page to be moved from main memory to disk ("paged out") to make room.
		A replacement algorithm or policy is used to select the page to be paged out, often this is the least recently used (LRU) algorithm.
	www.elook.org /computing/demand-paging.htm (201 words)

	Storage Organization and Management in TENEX
		Paging was therefore the logical alternative, and our study and experience with list processing systems(1,2) led us to believe that using a demand-paged virtual memory system for such computations was a feasible approach.
		Page table entries are one word, hence a page table for a 256K virtual memory is 512 words, or exactly one page.
		File pages are backed up to the disk by setting a request bit in the CST which causes the swapper to move the page to the disk instead of the drum.
	www.opost.com /dlm/tenex/fjcc72 (5844 words)

	Access verification arrangement for digital data processing system which has demand-paged memory with page crossing ...
		When a program requires data in pages which may not be physically present in the memory, the operating system transfers the entire page from the disk containing the page of data into a page in the memory.
		Similarly, locations in page (N+1) of the virtual address space are physically located in page (1) of the physical address space in memory 11, and the addresses in page (N+2) of the virtual address space are in page (5) in the physical address space.
		The page table entry also includes a valid bit V and modify bit M, which are not relevant to this invention, and a protection field PROT which identifies the access rights of the various programs to the data in that page.
	www.freepatentsonline.com /4821169.html (6329 words)

	CSE 120 -- Nachos Project 3: Virtual Memory (Fall 2002)
		Demand paging and page replacement together allow your kernel to "overbook" memory by executing more processes than would fit in machine memory at any one time, using page faults to "juggle" the available physical page frames among the larger number of process virtual pages.
		In this part, allocate a physical page for the virtual page and use your code from part 1 to initialize it, mark the PTE as valid, and return from the exception.
		Cleaning pages is an expensive operation, and it could even lead to deadlock in extreme cases, if for example a page is needed for buffering during the disk write.
	www-cse.ucsd.edu /classes/fa02/cse120/projects/vm.html (2968 words)

	[No title]
		The virtual memory is implemented by paging, and the page size is 4096 bytes.
		Assume that the page to be replaced is modified 70 percent of the time.
		Assume that 80 percent of the accesses are in the associative memory and that, of the remaining, 10 percent (or 2 percent of the total) cause page faults.
	www.inf.ufpr.br /~roberto/ci215ex6 (846 words)

	Lecture 7 - Caching and TLBs; Caching and Demand Paged Virtual Memory
		On a miss, the page table(s) are referenced and the appropriate page frame retrieved.
		Demand Paging is where you only load pages from disk into memory when an address on that page is needed by the CPU.
		The page table can have pointers to either pages that have been loaded into physical memory, or it can have pointers to pages that are still on the disk.
	www-scf.usc.edu /~csci402/crowley/lect7.html (3674 words)

	[No title]
		A free page is a page of physical memory not mapped to a virtual address; that is, not currently being used by any process or by the system itself.
		Pages are not loaded in memory until are "demanded" by a process -- hence the term, demand paging.
		Demand loading eliminates the need to allocate main memory to rarely accessed routines and code, such as error handling routines, which in some instances might account for a large percentage of a program's code.
	www.ozones.com /grumman/secondary/mem_mgt.txt.htm (11093 words)

	Proceedings of the 3rd USENIX Windows NT Symposium, July 12-15, 1999, Seattle, Washington
		The binary for desktop applications is demand paged so we examine the utilization of the code pages brought in during startup.
		Interestingly, netscape and photoshop touch almost every code page in their main binary during startup suggesting that even with demand paging the entire application is loaded to memory from disk.
		Compared to paged, reordered-paged minimizes the number of pages needed by the application, effectively reducing the number of bytes transferred and the number of requests to the server that have to be made.
	www.usenix.org /events/usenix-nt99/full_papers/lee/lee_html (4191 words)

	[No title]
		In each column, circle the page that the reference pointer currently points to after the page reference heading the column is satisfied.
		If the required page number is not in the TLB, then after the TLB lookup completes, the required page map table entry is read from Main Memory.
		Optimum means the page size that minimizes the amount of memory lost to implement paging.
	ei.cs.vt.edu /~cs3204/summer.95/ProblemArchive/Archive_Memory.html (1931 words)

	CSE 120 -- Nachos Project 3: Virtual Memory (Fall 2001)
		First, you will implement demand paging using page faults to dynamically load process virtual pages on demand, rather than initializing page frames for each process in advance at Exec time as you did in Project 2.
		You will soon discover that the first page fault is different than subsequent ones on code and data pages because on the first fault you need to read from the executable file, and on the second you need to read from the backing store.
		Implement test programs that (1) generate good locality (most references are to a small subset of pages), and (2) generate poor locality (everything is referenced repeatedly in a pattern), and (3) random locality (pages are effectively referenced randomly).
	www-cse.ucsd.edu /classes/fa01/cse120/project/vm.html (2694 words)

	[No title] (Site not responding. Last check: 2007-10-09)
		Consider a demand paged system where the page size is 512K.
		When the page's address is in the associative memory only one memory access is required to reference an address.
		1% of the remaining time(when the page's reference is not in the associative memory) a page fault occurs.
	www.cs.usyd.edu.au /~cs3/comp3009/tutes/week10.txt (368 words)

	Pick operating system -- Facts, Info, and Encyclopedia article (Site not responding. Last check: 2007-10-09)
		Each file may be split into as many buckets as the database engineer wishes, although changing this later requires the database to be quiescent.
		All files start as a contiguous group of disk pages, and grow by linking additional "overflow" pages from unused disk space.
		On the Microdata implementation, a ((usually plural) a necessary commodity for which demand is constant) BASIC-like language called Data/BASIC with numerous syntax extensions for database operations was the primary programming language for applications.
	www.absoluteastronomy.com /encyclopedia/p/pi/pick_operating_system.htm (911 words)

	Quiz 2 Answers (Site not responding. Last check: 2007-10-09)
		Since physical page 5's first byte is at physical address 0x5000, the corresponding physical address must be 0x5100.
		Comment: A page needs to be swapped out of physical memory only if there were no free physical pages available for the page being swapped in.
		The fact that a page was swapped out means that physical memory was full at that point in time.
	www.digipen.edu /~mgrove/CS180/Answers/quiz2.htm (662 words)

	[No title]
		You are to write a program to test the performance of two page replacement algorithms in a demand paged virtual memory management system.
		For example, with a frame allocation of 10%, the number of memory frames allocated to the job is 10% of the total number of logical pages in the job.
		If a page fault occurs, you must invoke the appropriate page replacement algorithm to choose a page to replace, update the page table, and continue.
	cms.dt.uh.edu /Faculty/BerrachedA/CS4315/Projects/Proj4.doc (900 words)

	Project 3: Virtual memory management
		If the selected page frame is currently in use and the data on the page has been modified, write the data in the page frame to backing store.
		Locate the page for which the fault was generated on the backing store; initiate I/O to load the page into the page frame selected in the previous steps.
		When the page is accessed for the first time, the page fault is handled by allocating a new page, which is then cleared (filled with zeros).
	www.cs.ucsb.edu /~acha/courses/99/fall/project3.html (2409 words)

	Citations: MachineIndependent Virtual Memory Management for Paged Uniprocessor and Multiprocessor Architectures - ... (Site not responding. Last check: 2007-10-09)
		....the system s page fault handler to guarantee that results are the same as if data had been copied to distinct system pages.
		: If the page s output reference count is nonzero, the system recovers the process by invalidating all mappings of the page, copying the contents of the page to a new page, swapping pages in the memory object, and mapping the new page to the same virtual address in the process, with writing.
		....occur when the required page is in memory, but the page table does not contain the required translation to the page.
	citeseer.ist.psu.edu /context/67208/18629 (3066 words)

	[No title]
		Page table has "present" \(valid\) bit)J 126 210 :M 3.174.317(if present, pointer to page frame in memory)J 126 228 :M 2.283.228(if not present, go to disk)J 126 264 :M 3.529.353(2.
		Hardware traps to OS on reference to invalid page)J 126 282 :M 2.654.265(\(In MIPS/Nachos, trap on TLB miss, OS checks page table)J 126 300 :M 5.024.502(valid bit\))J 126 336 :M 2.796.28(3.
		TLB has "present" \(valid\) bit)J 126 120 :M 3.174.317(if present, pointer to page frame in memory)J 126 138 :M 2.981.298(if not present, use page table in memory)J 126 174 :M 3.038.304(2.
	http.cs.berkeley.edu /~tea/cs162sp95/notes/l15.ps (771 words)

	MikeZintel's WebLog : Wednesday, December 08, 2004 - Posts
		The operating system loader creates an association between executable code in a native DLL or EXE and the process’s virtual space, and then uses demand paging system to back the virtual address space with physical memory as needed to actually execute the instructions.
		In the case of compressed files, the physical memory backing this address space is demand paged and fully shared across all processes.
		They are backed with demand paged and shared physical memory as needed.
	blogs.msdn.com /mikezintel/archive/2004/12/08.aspx (3746 words)

	Citations: Pointer Swizziing at Page Fault Time: Efficiently Supporting Huge Address Spaces on Standard Hardware - ... (Site not responding. Last check: 2007-10-09)
		A swizzling manager will provide a page of data in which addresses that refer to objects anywhere within the container are replaced with shorter addresses (ones within the machine s address range) which, when dereferenced will be used by the swizzling manager to provide the correct data
		This is the abstraction delivered by demand paged virtual memory and memory mapped files in conventional operating systems.
		Dirty pages must be written to a different site to guarantee that at least one self consistent copy of the store exists at any time.
	citeseer.ist.psu.edu /context/2001471/0 (279 words)

	paged - OneLook Dictionary Search
		Tip: Click on the first link on a line below to go directly to a page where "paged" is defined.
		Phrases that include paged: paged memory management unit, demand paged, front paged
		Words similar to paged: page, beeped, summoned, more...
	www.onelook.com /?w=paged&ls=a (264 words)

	ERCB: DDJ Programmer's Bookshelf December 1992
		You can dereference a pointer to access a page of memory, even if that page is currently on disk; a page-fault handler within the operating system will take care of loading the page without you being aware of it.
		Obviously, the presence of virtual memory is no more relevant to your average programmer than is, say, the presence of an instruction prefetch queue on the processor.
		As Stone shows, paged virtual memory depends on the fact that all programs have reasonably sized working sets or "footprints;" that is, that all programs can run for a while with only discrete, page-sized bits of themselves in memory at any given time.
	www.ercb.com /ddj/1992/ddj.9212.html (1414 words)

	[No title]
		Below is the outline of one possible algorithm for implementing a demand paged memory management system within the context of Project #3.
		This would allow you to store the trace as an integer array, as was the case in Project #2.
		Calculate which page of the job is being referenced.
	faculty.kutztown.edu /rieksts/343/paging.html (626 words)

	Demand-Paged Virtual Memory (new) [ Introduction to MPE XL for MPE V Programmers Migration Guide ] (Site not responding. Last check: 2007-10-09)
		The system actually stores files page by page at physical addresses.
		The operating system keeps a map, a table of correspondences between virtual addresses and physical addresses, and translates between them as needed.
		The MPE XL memory manager fetches several adjacent pages directly from disk as required.
	docs.hp.com /cgi-bin/doc3k/B3036790005.10124/5 (361 words)

	► » Looking For "Sun demand paged SPARC" File Format Information (Site not responding. Last check: 2007-10-09)
		Looking For "Sun demand paged SPARC" File Format Information
		Correct; this is a SunOS 4.x a.out file.
		"Demand paged" indicates that the magic number is ZMAGIC.
	www.comp-sys-it.org /Looking-For-Sun-demand-paged-SPARC-File-Format-Information-5258663.html (321 words)

	VAX (Site not responding. Last check: 2007-10-09)
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		VAX is a 32-bit computing architecture that supports an orthogonal machine language and virtual addressing (i.e.
		Visit NewsDaily for the latest headlines from around the world.
	www.sciencedaily.com /encyclopedia/vax (649 words)

	[No title] (Site not responding. Last check: 2007-10-09)
		# 0 short 0x0160 mipseb >20 short 0407 executable >20 short 0410 pure >20 short 0413 demand paged >8 long >0 not stripped >8 long 0 stripped >22 byte >0 - version %ld.
		>23 byte >0 %ld 0 short 0x0162 mipsel >20 short 0407 executable >20 short 0410 pure >20 short 0413 demand paged >8 long >0 not stripped >8 long 0 stripped >23 byte >0 - version %ld.
		>23 byte >0 %ld 0 short 0x6201 swapped mipsel >20 short 03401 executable >20 short 04001 pure >20 short 05401 demand paged >8 long >0 not stripped >8 long 0 stripped >22 byte >0 - version %ld.
	distro.ibiblio.org /pub/linux/distributions/sotlinux/sotlinux-2003/SOTL_2003_DESKTOP/Install/live/usr/share/printconf/mf.magic (4519 words)

	comp.sys.sun.admin: By Thread
		Looking For "Sun demand paged SPARC" File Format Information Thomas Dineen
		Re: Looking For "Sun demand paged SPARC" File Format Information Richard L. Hamilton
		Re: Looking For "Sun demand paged SPARC" File Format Information Jonathan Adams
	unix.derkeiler.com /Newsgroups/comp.sys.sun.admin/2004-08 (1717 words)

	How can I tell an a.out binary from an ELF one? (Site not responding. Last check: 2007-10-09)
		How can I tell an a.out binary from an ELF one?
		It will either tell you 'mc68020 demand paged' if it is an a.out binary, and give a longer (self-explanatory) description if it is ELF.
		If it says something about a "DLL jump", the binary is in a.out format; otherwise, it's in ELF.
	www.linux-m68k.org /faq/howtellaoutelf.html (110 words)

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