
	Where results make sense

Topic: Physical memory

Related Topics

Memory management

Memory allocation

Computer storage

Hard disk

Floppy disk

Magnetic tape

RAM

In the News (Fri 13 Nov 09)

Northern Trust

Marvin Harrison

Peter Chernin

Gary Locke

Match Play

Penelope Cruz

Mickey Rourke

AR Rahman

Danny Boyle

Hugh Jackman

	Memory-Loss.com - Feel better!
		Memory processes can be itemized according to the time they take: very short-term memory, which lasts about 100 milliseconds; short-term memory, which is of a few seconds’ duration; working memory, which stores recent experiences; and long-term memory, which houses verbal material that has been rehearsed and motor skills that have been practiced.
		The basal ganglia region is focused on habits and physical skills, and the cerebellum, at the base of the brain, concentrates on conditioned learning and reflexes.
		A little memory loss is normal with age but if you are experiencing a noticeable decrease in memory before age 40 then your memory loss may not be normal....
	www.memory-loss.com (640 words)

	Virtual memory - Wikipedia, the free encyclopedia
		The term "virtual memory" is often confused with "memory swapping" (or "page/swap file" use), probably due in part to the prolific Microsoft Windows family of operating systems referring to the enabling/disabling of memory swapping as virtual memory.
		To properly implement virtual memory the CPU (or a device attatched to it) must provide a way for the operating system to map virtual memory to physical memory and for it to detect when an address is required that does not currently relate to main memory so that the needed data can be swapped in.
		The decision of when to use cache and when to use main memory is generally dealt with by hardware so generally both are regarded together by the programmer as simply physical memory.
	en.wikipedia.org /wiki/Virtual_memory (3137 words)

	Explore the Linux memory model
		Thus, the maximum amount of physical memory that could be handled by the kernel was the amount that could be mapped into kernel's virtual address space minus the space needed to map the kernel code itself.
		Memory management is a large, complex, and time-consuming set of tasks, one that is difficult to achieve because crafting a model how systems behave in real-world, multi-programmed environments is a tough job.
		Kernel comparison: Improved memory management in the 2.6 kernel (developerWorks, March 2004) details new techniques to improve the use of large amounts of memory, reverse mapping, storage of page-table entries in high memory, and the greater stability of the memory manager.
	www-128.ibm.com /developerworks/linux/library/l-memmod (4296 words)

	Memory Management 1: physical memory (Site not responding. Last check: 2007-10-05)
		A memory manager (that is, a physical memory manager) is one of the components at the lowest level of every operating system, and it is vital for the splitting-up of your computer’s memory.
		With a properly separated physical memory manager your OS will be able to take full advantage of a machine with huge amounts of memory with no changes outside of the memory manager; without, you’d probably need to recompile all your applications (not just the kernel) which could get tedious, to say the least.
		Since your memory manager should separate all the machine-specific memory stuff from the rest of the kernel, it’s polite to enable paging before your return, and it’s polite to keep the address format the same (if not, then the return address on the stack from the last function call will be wrong).
	www.openbg.net /sto/os/xml/memory1.html (4231 words)

	System Performance Tuning, 2nd Edition: Chapter 4: Memory
		Memory is taken from the free list by processes, and returned to it when the process exits or by the action of the page scanner, which tries to ensure that there is a small amount of memory free for immediate use at all times.
		Should a page of anonymous memory be stolen by the page scanner, the data is written to disk-based swap space (that is, the allocation is moved from memory to disk), and the memory is freed for reuse.
		The entire data memory hierarchy[12] is evaluated, including the latency to the primary caches, secondary caches, main memory, and the latency effects of a TLB miss.
	www.oreilly.com /catalog/spt2/chapter/ch04.html (10259 words)

	Feature: High Memory In The Linux Kernel (Site not responding. Last check: 2007-10-05)
		Memory in the ZONE_NORMAL region is mapped by the kernel in the upper region of the linear address space.
		It is not necessary to have 3 GB of physical memory to map it all.
		If the physical pages are mapped into process space, then when the process makes a system call, the kernel should have access to copy any memory to kernel space because it's in the context of the calling process and can use its page tables.
	kerneltrap.org /node/view/2450 (5044 words)

	Windows 2000 Memory Management
		Virtual memory is a file on the hard disk that’s designed to be addressable in the same way that physical memory is. The basic idea is that when the physical memory gets to be too full, Windows moves some of the physical memory’s contents to virtual memory, thus freeing space within the physical memory.
		When the machine needs to work with data that was moved to virtual memory, something else is transferred from physical memory to virtual memory.
		Physical disk usage is different from partition usage because often multiple partitions will exist on a single physical disk.
	www.brienposey.com /kb/memory_management.asp (3231 words)

	Memory Management 1: physical memory (Site not responding. Last check: 2007-10-05)
		A memory manager (that is, a physical memory manager) is one of the components at the lowest level of every operating system, and it is vital for the splitting-up of your computer’s memory.
		With a properly separated physical memory manager your OS will be able to take full advantage of a machine with huge amounts of memory with no changes outside of the memory manager; without, you’d probably need to recompile all your applications (not just the kernel) which could get tedious, to say the least.
		Since your memory manager should separate all the machine-specific memory stuff from the rest of the kernel, it’s polite to enable paging before your return, and it’s polite to keep the address format the same (if not, then the return address on the stack from the last function call will be wrong).
	osdev.berlios.de /memory1.html (4231 words)

	Virtual versus Physical Memory
		Adding more memory may not be possible in the short term for several reasons: the cost of upgrading can be a barrier, or the system may not have any space to quickly add additional memory chips.
		Memory dumps cause the information in physical memory to be stored in the pagefile during a crash.
		Because there is only one physical reader on each physical disk, it takes longer to read.
	www.measureup.com /testobjects/MS_NT4W/5a8be17.htm (379 words)

	[No title]
		If the page to be discarded from physical memory came from an image or data file and has not been written to then the page does not need to be saved.
		Accesses to the swap file are very long relative to the speed of the processor and physical memory and the operating system must juggle the need to write pages to disk with the need to retain them in memory to be used again.
		For example, one of the virtual memory operations performs the correct actions when the process has attempted to access this virtual memory but finds (via a page fault) that the memory is not actually in physical memory.
	www.tldp.org /LDP/tlk/mm/memory.html (8338 words)

	What is memory? - A Word Definition From the Webopedia Computer Dictionary
		The term memory identifies data storage that comes in the form of chips, and the word storage is used for memory that exists on tapes or disks.
		Moreover, the term memory is usually used as a shorthand for physical memory, which refers to the actual chips capable of holding data.
		RAM (random-access memory): This is the same as main memory.
	www.webopedia.com /TERM/m/memory.html (756 words)

	CS322: Virtual Memory
		We saw that the earliest computer systems operated on a memory model that required that all of the memory required by a given process be allocated to it in a single, contiguous region of physical memory.
		Even if physical memory were large enough to hold any process that might be run on a given system, virtual memory can still be advantageous by allowing more processes to be (partially) memory resident at once, thus allowing for higher utilization of the CPU and/or allowing more interactive users to be online.
		In practice, however, this does not often occur, since virtual memory systems are generally multiprogrammed and thus are configured with sufficient physical memory to allow portions of many processes to be resident at once.
	www.cs.gordon.edu /courses/cs322/lectures/virtual_memory.html (5393 words)

	6.6 Virtual Memory, Protection, and Paging
		Thrashing is a degenerate case that occurs when there is insufficient memory at one level in the memory hierarchy to properly contain the working set required by the upper levels of the memory hierarchy.
		There are two primary causes of thrashing: (1) insufficient memory at a given level in the memory hierarchy, and (2) the program does not exhibit locality of reference.
		If insufficient memory is the cause of thrashing, an easy solution is to add more memory (if possible, it is rather hard to add more L1 cache when the cache is on the same chip as the processor).
	webster.cs.ucr.edu /AoA/Windows/HTML/MemoryArchitecturea3.html (1956 words)

	The Memory Management Glossary: P
		The page number of an address is usually found from the most significant bits of the address; the remaining bits yield the offset of the location within the page.
		The physical address space is the space of physical addresses.
		Under manual memory management, this usually occurs when one part of a program decides it has finished using a memory block, and is unaware that another part of the program is still using it.
	www.memorymanagement.org /glossary/p.html (1905 words)

	Determining Free Physical RAM and Using It to Improve Your Application
		When there is a shortage of physical memory, most modern operating systems will engage virtual memory capabilities using disk swap space to complement the physical memory.
		Determine the amount of free physical memory available (as described above) and see if it is negative, which would indicate that your system is paging to disk or is about to start.
		tells you there is enough physical memory at the moment, and if you can determine that you can count on that free memory being there long enough for your purposes, then you can trade this memory for performance by dynamically selecting a faster algorithm.
	developers.sun.com /solaris/articles/free_phys_ram.html (2471 words)

	Windows Incident Response: Windows Physical Memory Analysis
		As it turns out, the DFRWS 2005 Memory Challenge provides a great set of test files (2, actually) for testing any tools you're writing to parse a memory dump generated using dd.exe.
		Last year, I became aware of a paper by Mariusz Burdach that described how to analyze the contents of physical memory that was collected using dd/dd.exe.
		The results of the DFRWS Memory Challenge included two winning responses, one by Chris Betz, and the other by George M. Garner, Jr.
	windowsir.blogspot.com /2006/03/windows-physical-memory-analysis.html (1436 words)

	Disk Cache, Hybrid Disk Cache and RamDisk
		The amount of physical memory that can be safely allocated to a given product varies from system to system.
		For systems with relatively small amounts of physical memory, up to 256 MB, the amount of available memory may be in the order of 30 to 50 percent or less.
		The maximum amount of available physical memory at any moment cannot be predetermined precisely since it changes even as a system is active.
	www.superspeed.com /desktop/calcmem.php (280 words)

	IT Resource Center forums - How to limit the amount of used physical memory?
		Thanks Sarvesh, but dbc_max_pct is the maximum percentage of physical memory the system MAY use for caching.
		I need the system to act really as if there was only a given amount of physical memory.
		One process taking n megabytes of physical memory is not the same as removing an n megabytes DIMM.
	forums1.itrc.hp.com /service/forums/questionanswer.do?threadId=47137 (920 words)

	[No title] (Site not responding. Last check: 2007-10-05)
		Rather than just sending a 32-bit value to memory and asking for that byte, now you are asking the MMU for a specific page, and then the MMU will get a specific byte off of that page for you.
		With direct physical addressing, you would have to have 4GB of memory for the program to be able to use those addresses, but with virtual addresses, the MMU can place the virtual pages in different locations in physical memory.
		Because the MMU is hiding the virtual physical mapping from us, virtual pages don't need to be laid out in ascending order in physical memory.
	www.cs.umass.edu /~trekp/cs201/lecture_notes/lecture30.txt (1033 words)

	Virtual Memory
		You might think translating each address from virtual to physical is a crazy idea, because of how slow it is. However, you get memory protection from address translation, so it's worth the hardware needed to get memory protection.
		Basically, once the virtual address is translated to a physical address, then the physical address is passed to the cache, which checks to see if there is a cache hit.
		Virtual memory is handled partly by hardware (translation mechanism) and partly by the operating system (sets up page table, handles page faults, etc).
	www.cs.umd.edu /class/spring2003/cmsc311/Notes/Memory/virtual.html (2995 words)

	Physical memory
		Also referred to as the physical storage or the real storage.
		Physical memory is a term used to describe the total amount of memory installed in the computer.
		For example, if the computer has two 64MB memory modules installed it has a total of 128MB of physical memory.
	www.computerhope.com /jargon/p/physmemo.htm (58 words)

	Reduce your Linux memory footprint
		You can see that the memory use appears to be around 20MB less than Ubuntu required for the same set of apps (126 in physical memory and 17 in swap for a total of 143 versus 143 + 18 for a total of 161).
		The resident value represents the total amount of physical memory in use by the process, including shared libraries that are in use by other processes, and is typical of the sort of value you would expect from
		Now that you know how to analyze the memory use of your applications, you can simply repeat the process for all the application types you're interested in, trying out the various options available until you find the choice with the lowest memory requirements that still meets your needs functionally.
	www.ibm.com /developerworks/linux/library/l-linux-memory.html?ca=dgr-lnxw06LinuxMemory (4220 words)

	Technical Q&A QA1099: Reducing the size of Physical Memory in Open Firmware
		This is useful for testing purposes when you don't want to have to physically remove RAM such as on the earlier iMacs or PowerBooks which require disassembly.
		This option is discussed at the end of this QandA under the section "Setting the Physical Memory Size for Mac OS X using "maxmem" in Open Firmware".
		When specifying the size of memory present, the size must be a multiple of 200000 (or 2M) else the system may hang on start or enter a kernel panic.
	developer.apple.com /qa/qa2001/qa1099.html (1355 words)

	Privacy Policy
		If you contact Memory Suppliers or our customer service representatives by telephone, e-mail or letter, we may keep a record of your correspondence or comments.
		Fulfillment: The information collected by Memory Suppliers is used only for the limited purposes of processing orders, keeping you informed about your order status, for statistical purposes, for improving our site and its performance, to serve ads, and to notify you of products or special offers that may be of interest to you.
		Memory Suppliers provides free lifetime warranty on all merchandise in addition to the manufacturer's warranty and a full 30 days money back guarantee (we will also pay the shipping charge back to Memory Suppliers and there is absolutely no restocking fees).
	www.memorysuppliers.com /privacypolicy.html (1316 words)

	The Old New Thing : Myth: You need /3GB if you have more than 2GB of physical memory
		It can't be a misapprehension of a 1-1 mapping between physical memory and virtual memory, because that mapping is blatantly not one-to-one.
		You gave it a physical memory range and it returned the base of a range of linear addresses that could be used to access that physical memory.
		A very common manifestation of a stray pointer in kernel mode is memory corruption, which means that the component that crashes is rarely the one that caused the problem in the first place.
	blogs.msdn.com /oldnewthing/archive/2004/08/11/212720.aspx (6912 words)

	GPLHost:>_ Virtual Private Servers using Xen, Singapore, Florida (USA), Paris (France)
		Your virtual server will be hosted in a native LVM partition of physical servers for faster access (no slow NFS access) and we have never more than 12 to 16 customers on the same server to provide good quality.
		Memory is not shared and not burstable among users, the physical memory is simply split a slice that we rent to you, the same way we do with LVM HDD slices.
		We suggest you to take enough memory to be able to recompile the software you will need.
	www.gplhost.com /hosting-vps.html (1602 words)

	MAPPING VIRTUAL TO PHYSICAL MEMORY
		The PA-RISC hardware attempts to convert a virtual address to a physical address with the TLB or the block TLB.
		The algorithm for converting a virtual address to a physical address depends on the particular processor.
		may contain the space.offset (virtual address) corresponding to a physical address or it may have a pointer to a link list of alias structures, each of which has a space.offset pair.
	docs.hp.com /en/5965-4641/ch01s07.html (761 words)

Try your search on: Qwika (all wikis)