Windows 8 and 8.1 Forums


Do you really need Virtual Memory?

  1. #31


    There is a down side to doing this; Widows will lose some of its functionality, the page file can no longer be used as a memory back-up.
    I have no idea what that means.

    The only downside to doing this is the time it takes, but on some systems that can be considerable. There will be no loss in functionality except for hibernation which requires an intact pagefile.

    The setting forces the pagefile to be completely overwritten with zeros at system shutdown. This is a security measure only and has no other benefits. At startup Windows never uses the previous contents of the pagefile (except after a memory dump is created). Windows will not permit an application to access the pagefile for any purpose while Windows is running.

    This setting can be useful but it really only makes sense as part of a comprehensive security policy. Most systems have security issues that are much more serious. Finding a password in the pagefile is quite easy - if you know what it is. Finding an unknown password in a pagefile will be enormously difficult.

    This setting has been widely misrepresented on the Internet.

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  2. #32


    Posts : 9
    Windows 7 Ult


    Quote Originally Posted by LMiller7 View Post
    There is a down side to doing this; Widows will lose some of its functionality, the page file can no longer be used as a memory back-up.
    I have no idea what that means.

    The only downside to doing this is the time it takes, but on some systems that can be considerable. There will be no loss in functionality except for hibernation which requires an intact pagefile.

    The setting forces the pagefile to be completely overwritten with zeros at system shutdown. This is a security measure only and has no other benefits. At startup Windows never uses the previous contents of the pagefile (except after a memory dump is created). Windows will not permit an application to access the pagefile for any purpose while Windows is running.

    This setting can be useful but it really only makes sense as part of a comprehensive security policy. Most systems have security issues that are much more serious. Finding a password in the pagefile is quite easy - if you know what it is. Finding an unknown password in a pagefile will be enormously difficult.

    This setting has been widely misrepresented on the Internet.
    I like you. You challenge me and make me think.
    You know exactly what I mean,
    but you do not believe that the pagefile is used for physical memory back-up,
    and you do not think an application can access a pagefile.

    You do not think an application can access a pagefile
    The PageFile is not hardware; there is not a PageFile circuit or IC chip anywhere on the main board.
    The PageFile is software. It is a subprogram that is part of Windows. The PageFile and the memory controller are controlled by windows code, though the CPU. The program’s code tells Windows what to do to run the program. It tells what files are needed to run each operation, it also tells Windows the priority for each file.There is no way for Windows to know this without being told by the program’s code.Most of the Memory management is done automatically by Windows using information that was obtained from the program’s code. If the program’s code gives specific instruction to windows pertaining to the memory controller or PageFile, Windows executes the code (follows instructions). An application cannot access a pagefile directly, but I am a programmer and I assure you that you are 100% wrong; applications do access the pagefile through Windows. A program can have Pagefile use written into it. A computer is not smart, everything it does, it is following code from software (applications and Windows).

    Did you know that 4 core CPU usage has to be written into the operating system and the program’s code before all 4 cores can be used? The exact way all 4 cores are going to be used in every operation has to be written into the programs code, in a way the Windows understands. This means that Windows must have detailed usage code on how each core can be used, and the programmer of the application has to choose the appropriate code for that usage when it is needed. Windows XP had multi core usage written into it at midlife, it was poorly done. Visa is the first windows operating system that had multi core usage written into its core programing. Windows 7 and 8 are big improvements over Vista. More than 80 % of the programs are to simple for multi core usage to be written into there code. My point is, "code rules"; an application’s code can instruct Windows to do anything that complies with Widows code. You needed to understand this so that you will know how Windows must extensively interact with the program to run an operation. In the same way that the program (in order to be the most affective) has to tell Windows how to use the extra cores, Windows must also have the program's help (instructions) in order to be able to efficiently manage the memory. The friend that help write Windows XP, taught me most of what I know about programing (may he RIP). He was a Programing Engineer. The above spill about 4 core usage came directly from his mouth.


    you do not believe that the pagefile is used for physical memory back-up
    I have several Windows 7 computers, an Intel E8400 w/4 GB of memory, Intel QX9650 w/8GB of memory, Intel i7 2600K w/16 GB of memory. In every case, Windows manages the PageFile size, and the PageFile is the same size as the Physical memory. What in GODs green Earth would a PageFile do with 16 GB of hard drive space. With the Page file not losing its data at shut down, a back up would be an ideal use for this file. Windows 7 recovers better than any previous operating system after a power failure. If the used part of 16 GB of physical memory were backed up, this would make sense. The 16 GB pagefile is the most logical place.

    I use Microsoft Word on a regular bases. If the page is not saved when the computer is turned off, Word shows you that page in a column on the left, and ask you if you want to save it. Since programs are ran from memory, the PageFile would be an easy place to cache that file, and it would still be there when Window is turn back on. It would be easy to leave a directory in the PageFile that Window code would understand as an inventory or instructions. I do not know that my conclusions are correct, but I know what can be done, and I do know what is logical.

    Microsoft has never published a paper on exactly what they do with the Page file. Most opinions about what the pagefile is used for, comes from experiments users have performed. These users do not know how the pagefile is used, all they know is that program has problems when the pagefile is disabled. I am just another one of these people. I cannot prove you are wrong or I am right, but there is a lot of things that I have seen that point to me being right.

    There will be no loss in functionality except for hibernation which requires an intact pagefile.
    Think about what you just said. Ask yourself why. Logically, the PageFile is being used to back-up physical memory during hibernation. Physical memory will not retain data when the computer is off, the PageFile will. If the PageFile is not being used to back-up physical memory , why would the PageFile be needed for the computer to be able to
    hibernate?
    Last edited by Luke Warm; 12 Apr 2014 at 14:27.
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  3. #33


    Luke Warm

    I too am a programmer (amateur) and have studied the Windows memory management system extensively. I stand by everything I said previously. You appear to have some misconceptions about how Windows manages memory and how the pagefile is used.
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  4. #34


    Posts : 9
    Windows 7 Ult


    Quote Originally Posted by LMiller7 View Post
    Luke Warm

    I too am a programmer (amateur) and have studied the Windows memory management system extensively. I stand by everything I said previously. You appear to have some misconceptions about how Windows manages memory and how the pagefile is used.
    DiDo
    You did not debunk my logic, this is your opportunity to learn something new.

    I am a United States Air Force trained aircraft electronics technician. In the world of computers, no one knows everything. I am a Hardware Specialist. I have 9 computers on a network at my house. I have been repairing office equipment for 35 years and I now have a computer repair business. I, like you, am an also amateur programmer.

    I did ask a professional programmer today. He said that applications can and do access the pagefile through Windows. And programs can have Pagefile use written into them.
    I also ask him if the pagefile is ever used to back-up physical memory. He said it's possible, but he did not know.
    Last edited by Luke Warm; 12 Apr 2014 at 14:22.
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  5. #35


    Posts : 9
    Windows 7 Ult


    Quote Originally Posted by LMiller7 View Post
    Luke Warm

    I too am a programmer (amateur) and have studied the Windows memory management system extensively. I stand by everything I said previously. You appear to have some misconceptions about how Windows manages memory and how the pagefile is used.
    Commit charge - Wikipedia, the free encyclopedia
    "The commit charge increases when any program is opened and used, and goes down when a program is closed. It will also change when already-running programs allocate or free private virtual memory; for example, with the VirtualAlloc and VirtualFree APIs."

    As a programmer, you will understand the above quote:
    If a program has private virtual memory APIs, that would mean that applications do access the PageFile through Windows, and a program can have PageFile use written into it.

    As for "the pagefile is used for physical memory back-up", I still have no proof. That conclusion is a product of reverse engineering on my part. I think VirtualAlloc APIs could be used for this. Farther discussion from anyone that has proof one way or the other, is welcome.
    Last edited by Luke Warm; 14 Apr 2014 at 22:58.
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  6. #36


    If a program has private virtual memory, that would mean that applications do access the PageFile through Windows, and a program can have PageFile use written into it.
    Private use virtual memory is backed by the pagefile. But when or if this memory is ever written to the pagefile is entirely up to the memory management system. Applications do not control this. Any attempt by an application to open the pagefile for any access will fail.

    Applications use functions that may access the pagefile. But the application has no control over when or if this occurs. That is my point.

    a program can have PageFile use written into it.
    Show me an API function that can do this. Otherwise I see no point in continuing this.
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  7. #37


    Posts : 9
    Windows 7 Ult


    Quote Originally Posted by LMiller7 View Post
    If a program has private virtual memory, that would mean that applications do access the PageFile through Windows, and a program can have PageFile use written into it.
    Private use virtual memory is backed by the pagefile. But when or if this memory is ever written to the pagefile is entirely up to the memory management system. Applications do not control this. Any attempt by an application to open the pagefile for any access will fail.

    Applications use functions that may access the pagefile. But the application has no control over when or if this occurs. That is my point.

    a program can have PageFile use written into it.
    Show me an API function that can do this. Otherwise I see no point in continuing this.
    I already did.
    The memory management system is controlled by the Operating System, the OS follows instructions from the program.

    Quote from; Commit charge - Wikipedia, the free encyclopedia

    "The commit charge increases when any program is opened and used, and goes down when a program is closed. It will also change when already-running programs allocate or free private virtual memory; for example, with the VirtualAlloc and VirtualFree APIs."


    Quote from;
    Application programming interface - Wikipedia, the free encyclopedia

    "In computer programming, an application programming interface (API) specifies how some software components should interact with each other".


    VirtualAlloc API is short for "Virtual memory allocation application programming interface ".

    Allocation is another word for "management" or "controlling the way something is used".

    al·lo·ca·tion
    ˌaləˈkāSHən/
    noun
    noun: allocation

    • 1.
      the action or process of allocating or distributing something.
      "more efficient allocation of resources"
      synonyms: allotment, assignment, distribution, apportionment, sharing out, handing out, dealing out, doling out, giving out, dishing out, parceling out, rationing out, dividing up/out;
    Last edited by Luke Warm; 14 Apr 2014 at 23:40.
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  8. #38


    I know what VirtualAlloc does. I have used it. It does not read or write to the pagefile.
    This is getting nowhere. I will not comment further.
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  9. #39


    Posts : 9
    Windows 7 Ult


    Quote Originally Posted by LMiller7 View Post
    I know what VirtualAlloc does. I have used it. It does not read or write to the pagefile.
    This is getting nowhere. I will not comment further.
    Your right. An API does not read or write to the pagefile, An API is an instruction or a command.

    I too know what VirtualAlloc does, but for the people that don't, at the URL below is some good reading for you.
    VirtualAlloc function (Windows)

    Quote Originally Posted by LMiller7 View Post
    If a program has private virtual memory, that would mean that applications do access the PageFile through Windows, and a program can have PageFile use written into it.
    Private use virtual memory is backed by the pagefile. But when or if this memory is ever written to the pagefile is entirely up to the memory management system. Applications do not control this. Any attempt by an application to open the pagefile for any access will fail.

    Applications use functions that may access the pagefile. But the application has no control over when or if this occurs. That is my point.
    Microsoft disagrees with you. This is a quote from Microsoft directly saying that applications do access Virtual Memory. Access means writing to and reading from "specifically" memory addresses that are located in Virtual Memory.
    You can read this Quote at PrefetchVirtualMemory function (Windows)
    "The PrefetchVirtualMemory function is targeted at applications that know with reasonable confidence the set of addresses they will be accessing."


    Have a good night LMiller7.
    Last edited by Luke Warm; 15 Apr 2014 at 21:53.
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  10. #40


    Posts : 9
    Windows 7 Ult


    Some of the things I said in the “how virtual memory works” post, came from reverse engineering on my part. I know how windows works, and I tried to imagine the easiest way that windows might accomplish certain task. Since the post, I have done a lot of research. I have found lots of Microsoft documentation that directly supports my conclusions and none that debunks any of them. I not only stand by what I say, but I back it up with logic and Microsoft documentation.

    Here is a list of APIs; these are instructions applications can give to Window to control virtual memory usage.
    This is from Memory Management Functions (Windows)


    Virtual Memory Functions


    The following are the virtual memory functions.
    Function Description
    PrefetchVirtualMemory Prefetches virtual address ranges into physical memory.
    VirtualAlloc Reserves or commits a region of pages in the virtual address space of the calling process.
    VirtualAllocEx Reserves or commits a region of pages in the virtual address space of the specified process.
    VirtualAllocExNuma Reserves or commits a region of memory within the virtual address space of the specified process, and specifies the NUMA node for the physical memory.
    VirtualFree Releases or decommits a region of pages within the virtual address space of the calling process.
    VirtualFreeEx Releases or decommits a region of memory within the virtual address space of a specified process.
    VirtualLock Locks the specified region of the process's virtual address space into physical memory.
    VirtualProtect Changes the access protection on a region of committed pages in the virtual address space of the calling process.
    VirtualProtectEx Changes the access protection on a region of committed pages in the virtual address space of the calling process.
    VirtualQuery Provides information about a range of pages in the virtual address space of the calling process.
    VirtualQueryEx Provides information about a range of pages in the virtual address space of the calling process.
    VirtualUnlock Unlocks a specified range of pages in the virtual address space of a process.
    Last edited by Luke Warm; 20 Apr 2014 at 08:44.
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Do you really need Virtual Memory?
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