Page File usage in XP

Discussion in 'NZ Computing' started by Nathan Mercer, Jan 26, 2006.

  1. S Roby wrote:

    > I'm running XP with 1G of RAM
    > So why have I got 129M of pagefile usage??


    Processes ask for an allocation of Virtual memory space from the
    system, and they may ask for a lot more memory than what they ever
    actually use. That memory space has to come from somewhere. When you
    have a pagefile the system can allocate it into there, otherwise it has
    to be assigned into real RAM, stopping you from "using" it.

    Cheers
    Nathan
     
    Nathan Mercer, Jan 26, 2006
    #1
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  2. Nathan  Mercer

    -=rjh=- Guest

    S Roby wrote:
    > I'm running XP with 1G of RAM
    > So why have I got 129M of pagefile usage??


    Oh, you are probably running Firefox

    :)
     
    -=rjh=-, Jan 26, 2006
    #2
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  3. Nathan  Mercer

    S Roby Guest

    I'm running XP with 1G of RAM
    So why have I got 129M of pagefile usage??
     
    S Roby, Jan 26, 2006
    #3
  4. Nathan  Mercer

    Dave Doe Guest

    In article <Fn0Cf.22791$>, le
    says...
    > I'm running XP with 1G of RAM
    > So why have I got 129M of pagefile usage??


    Shouldn't you have your pagefile settings at:
    1536/1536

    IIRC MS recommend 1.5 x RAM.

    --
    Duncan
     
    Dave Doe, Jan 26, 2006
    #4
  5. Nathan  Mercer

    XP Guest

    On Thu, 26 Jan 2006 10:12:12 GMT, le (S Roby) wrote:

    >I'm running XP with 1G of RAM
    >So why have I got 129M of pagefile usage??





    Far to low it should use all that is Free.

    I have set mine to 500megs as it was up in the gig range
     
    XP, Jan 26, 2006
    #5
  6. Nathan  Mercer

    Crash Guest

    Nathan Mercer wrote:
    > S Roby wrote:
    >
    >
    >>I'm running XP with 1G of RAM
    >>So why have I got 129M of pagefile usage??

    >
    >
    > Processes ask for an allocation of Virtual memory space from the
    > system, and they may ask for a lot more memory than what they ever
    > actually use. That memory space has to come from somewhere. When you
    > have a pagefile the system can allocate it into there, otherwise it has
    > to be assigned into real RAM, stopping you from "using" it.


    I am no Windows programmer but I am curious about the statement that processes
    can ask for virtual memory.

    I would have thought that 'processes' could ask for memory and that the OS would
    determine if real or virtual memory was allocated. Is this not the case?

    Crash
     
    Crash, Jan 27, 2006
    #6
  7. Nathan  Mercer

    S Roby Guest

    In article <>, "Nathan Mercer" <> wrote:
    >
    >S Roby wrote:
    >
    >> I'm running XP with 1G of RAM
    >> So why have I got 129M of pagefile usage??

    >
    >Processes ask for an allocation of Virtual memory space from the
    >system, and they may ask for a lot more memory than what they ever
    >actually use. That memory space has to come from somewhere. When you
    >have a pagefile the system can allocate it into there, otherwise it has
    >to be assigned into real RAM, stopping you from "using" it.
    >


    True
    But I have RAM to burn (1G)
    Are some processes programed to use x amont of vitual ram??

    I used to just disable the page file (set to 0M)
    Worked fine except my (old) epson injet refused to print
     
    S Roby, Jan 27, 2006
    #7
  8. Nathan  Mercer

    S Roby Guest

    In article <>, -=rjh=- <> wrote:
    >S Roby wrote:
    >> I'm running XP with 1G of RAM
    >> So why have I got 129M of pagefile usage??

    >
    >Oh, you are probably running Firefox
    >


    yes
     
    S Roby, Jan 27, 2006
    #8
  9. Nathan  Mercer

    S Roby Guest

    In article <>, Dave Doe <> wrote:
    >In article <Fn0Cf.22791$>, le
    >says...
    >> I'm running XP with 1G of RAM
    >> So why have I got 129M of pagefile usage??

    >
    >Shouldn't you have your pagefile settings at:
    >1536/1536
    >
    >IIRC MS recommend 1.5 x RAM.



    Doesnt this go back to the old days of Win3.1 when 8M was alot of RAM
     
    S Roby, Jan 27, 2006
    #9
  10. Nathan  Mercer

    S Roby Guest

    In article <>, XP <> wrote:
    >On Thu, 26 Jan 2006 10:12:12 GMT, le (S Roby) wrote:
    >
    >>I'm running XP with 1G of RAM
    >>So why have I got 129M of pagefile usage??

    >
    >
    >
    >
    >Far to low it should use all that is Free.
    >
    >I have set mine to 500megs as it was up in the gig range
    >
    >


    Mine is set to 500M
    129M is being used
     
    S Roby, Jan 27, 2006
    #10
  11. Nathan  Mercer

    Enkidu Guest

    Crash wrote:
    > Nathan Mercer wrote:
    >
    >> S Roby wrote:
    >>
    >>
    >>> I'm running XP with 1G of RAM
    >>> So why have I got 129M of pagefile usage??

    >>
    >>
    >>
    >> Processes ask for an allocation of Virtual memory space from the
    >> system, and they may ask for a lot more memory than what they ever
    >> actually use. That memory space has to come from somewhere. When you
    >> have a pagefile the system can allocate it into there, otherwise it has
    >> to be assigned into real RAM, stopping you from "using" it.

    >
    >
    > I am no Windows programmer but I am curious about the statement that
    > processes can ask for virtual memory.
    >
    > I would have thought that 'processes' could ask for memory and that the
    > OS would determine if real or virtual memory was allocated. Is this not
    > the case?
    >

    Sort of. A process has an address space. It asks for x bytes of that
    address space. The OS maps that to real memory or a page file.

    Cheers,

    Cliff
     
    Enkidu, Jan 27, 2006
    #11
  12. On Fri, 27 Jan 2006 21:42:23 +1300, Enkidu <>
    wrote:

    >Crash wrote:
    >> Nathan Mercer wrote:
    >>
    >>> S Roby wrote:
    >>>
    >>>
    >>>> I'm running XP with 1G of RAM
    >>>> So why have I got 129M of pagefile usage??
    >>>
    >>>
    >>>
    >>> Processes ask for an allocation of Virtual memory space from the
    >>> system, and they may ask for a lot more memory than what they ever
    >>> actually use. That memory space has to come from somewhere. When you
    >>> have a pagefile the system can allocate it into there, otherwise it has
    >>> to be assigned into real RAM, stopping you from "using" it.

    >>
    >>
    >> I am no Windows programmer but I am curious about the statement that
    >> processes can ask for virtual memory.
    >>
    >> I would have thought that 'processes' could ask for memory and that the
    >> OS would determine if real or virtual memory was allocated. Is this not
    >> the case?
    >>

    >Sort of. A process has an address space. It asks for x bytes of that
    >address space. The OS maps that to real memory or a page file.
    >
    >Cheers,
    >
    >Cliff


    Or, if it is sensible, the OS does not map the requested memory at all
    unless the program actually reads or writes the memory. Lots of
    programs ask for stupid amounts of memory (eg 1 Gibyte), and then only
    use a very small amount of it. If actual RAM or swap space was
    allocated, the system would be overwhelmed.

    Most OSes these days (including Win2k and WinXP) allocate actual RAM
    based on a concept called the working set. That means that the OS
    only has in RAM the actual pages that the program is using currently.
    It keeps least recently used timestamps for all pages and swaps out
    read/write pages and deletes read only pages when they are not being
    used any more.

    If you get a copy of Process Explorer from www.sysinternals.com, it
    has a column on its display for the working set size the OS currently
    has allocated for each program. When the total of the working sets is
    more than the actual RAM available, then you start to get excessive
    swapping and every thing grinds to a halt (swapper thrashing).

    Some programs seem to not be very good at managing their RAM usage and
    have excessive working set sizes. My largest working set at the
    moment is Mozilla with about 82 Mibytes! Mozilla and Firefox seem to
    be particularly bad at memory management and memory usage. Next
    largest is OpenOffice 2.0.1 with 21 Mibytes, which it should not have
    as I have not got any documents open in OO at present. I did have
    lots of documents open earlier, but now I should have only the
    quickstarter program running and its RAM usage should be minimal.
     
    Stephen Worthington, Jan 27, 2006
    #12
  13. Nathan  Mercer

    Crash Guest

    Stephen Worthington wrote:
    > On Fri, 27 Jan 2006 21:42:23 +1300, Enkidu <>
    > wrote:
    >
    >
    >>Crash wrote:
    >>

    [snip]
    >>>
    >>>I am no Windows programmer but I am curious about the statement that
    >>>processes can ask for virtual memory.
    >>>
    >>>I would have thought that 'processes' could ask for memory and that the
    >>>OS would determine if real or virtual memory was allocated. Is this not
    >>>the case?
    >>>

    >>
    >>Sort of. A process has an address space. It asks for x bytes of that
    >>address space. The OS maps that to real memory or a page file.
    >>
    >>Cheers,
    >>
    >>Cliff

    >
    >
    > Or, if it is sensible, the OS does not map the requested memory at all
    > unless the program actually reads or writes the memory. Lots of
    > programs ask for stupid amounts of memory (eg 1 Gibyte), and then only
    > use a very small amount of it. If actual RAM or swap space was
    > allocated, the system would be overwhelmed.
    >
    > Most OSes these days (including Win2k and WinXP) allocate actual RAM
    > based on a concept called the working set. That means that the OS
    > only has in RAM the actual pages that the program is using currently.
    > It keeps least recently used timestamps for all pages and swaps out
    > read/write pages and deletes read only pages when they are not being
    > used any more.

    [snip]

    In the mainframe environment I work in applications have no direct control of
    memory. Data declarations and operations such as file opens data moves etc. use
    memory but it is all controlled by the compiler (memory estimates for data) and
    the OS (memory allocation at runtime). The application cannot request n bytes
    of memory and then self-manage it.

    Crash.
     
    Crash, Jan 27, 2006
    #13
  14. Nathan  Mercer

    Enkidu Guest

    Crash wrote:
    > Stephen Worthington wrote:
    >
    >> On Fri, 27 Jan 2006 21:42:23 +1300, Enkidu <>
    >> wrote:
    >>
    >>
    >>> Crash wrote:
    >>>

    > [snip]
    >
    >>>>
    >>>> I am no Windows programmer but I am curious about the statement that
    >>>> processes can ask for virtual memory.
    >>>>
    >>>> I would have thought that 'processes' could ask for memory and that
    >>>> the OS would determine if real or virtual memory was allocated. Is
    >>>> this not the case?
    >>>>
    >>>
    >>> Sort of. A process has an address space. It asks for x bytes of that
    >>> address space. The OS maps that to real memory or a page file.
    >>>
    >>> Cheers,
    >>>
    >>> Cliff

    >>
    >>
    >>
    >> Or, if it is sensible, the OS does not map the requested memory at all
    >> unless the program actually reads or writes the memory. Lots of
    >> programs ask for stupid amounts of memory (eg 1 Gibyte), and then only
    >> use a very small amount of it. If actual RAM or swap space was
    >> allocated, the system would be overwhelmed.
    >>
    >> Most OSes these days (including Win2k and WinXP) allocate actual RAM
    >> based on a concept called the working set. That means that the OS
    >> only has in RAM the actual pages that the program is using currently.
    >> It keeps least recently used timestamps for all pages and swaps out
    >> read/write pages and deletes read only pages when they are not being
    >> used any more.

    >
    > [snip]
    >
    > In the mainframe environment I work in applications have no direct
    > control of memory. Data declarations and operations such as file opens
    > data moves etc. use memory but it is all controlled by the compiler
    > (memory estimates for data) and the OS (memory allocation at runtime).
    > The application cannot request n bytes of memory and then self-manage it.
    >

    In mainframe MVS you can have at least *some* control over where memory
    is allocated. For example, you can allocate private memory or shared
    unpaged or shared paged memory. From memory there's some other
    categories of memory too. All the user sees is the address space,
    although parts of the address space are allocated to shared, private and
    unshared, so you kind of know what type you are getting and whether or
    not it is shared or whatever. Compiled programs probably don't know even
    this but assembler programs do.

    Cheers,

    Cliff
     
    Enkidu, Jan 27, 2006
    #14
  15. Nathan  Mercer

    David Guest

    S Roby wrote:
    > In article <>, XP <> wrote:
    >> On Thu, 26 Jan 2006 10:12:12 GMT, le (S Roby) wrote:
    >>
    >>> I'm running XP with 1G of RAM
    >>> So why have I got 129M of pagefile usage??

    >>
    >>
    >>
    >> Far to low it should use all that is Free.
    >>
    >> I have set mine to 500megs as it was up in the gig range
    >>
    >>

    >
    > Mine is set to 500M
    > 129M is being used


    Not necessarily used, 129M is 'claimed'. Processes have allocated
    memory, but windows doesn't know if that memory will be used or not, so
    it has been assigned to the pagefile. When it is actually used it will
    be in RAM unless the RAM is full (in which case stuff will be moved from
    the pagefile to RAM and vice versa in a crazy manner causing your
    harddrive to make awful noises). The allocation in the pagefile is
    essentially to ensure that the memory will be definitely available (if
    your harddrive and RAM were full, and windows couldn't allow access to
    memory it allocated earlier, very bad things would happen).
     
    David, Jan 28, 2006
    #15
  16. Nathan  Mercer

    Murray Symon Guest

    On Sun, 29 Jan 2006 01:31:52 +0000, S Roby wrote:

    > In article <%iICf.49115$>, David <>
    > wrote:
    >>S Roby wrote:
    >>> In article <>, XP

    >> <> wrote:
    >>>> On Thu, 26 Jan 2006 10:12:12 GMT, le (S Roby) wrote:
    >>>>
    >>>>> I'm running XP with 1G of RAM
    >>>>> So why have I got 129M of pagefile usage??
    >>>>
    >>>>
    >>>>
    >>>> Far to low it should use all that is Free.
    >>>>
    >>>> I have set mine to 500megs as it was up in the gig range
    >>>>
    >>>>
    >>>>
    >>> Mine is set to 500M
    >>> 129M is being used

    >>
    >>Not necessarily used, 129M is 'claimed'. Processes have allocated memory,
    >>but windows doesn't know if that memory will be used or not, so it has
    >>been assigned to the pagefile. When it is actually used it will be in RAM
    >>unless the RAM is full (in which case stuff will be moved from the
    >>pagefile to RAM and vice versa in a crazy manner causing your harddrive
    >>to make awful noises)

    >
    > Back in Win 3.1 (& win95) i used to wonder about Win using the HD
    > (pagefile) to simulate real ram & then using RAM to to cache the HD. Bit
    > if a vicious circle.


    It can be, but only if not managed properly. This may have been the problem
    with early Windows (prior to NT). I seem to recall problems even with
    Windows 95 being too aggressive with its allocation of RAm for disk caching.

    The key is to keep the data most likely needing access in RAM and the data
    least likely needing access on disk (in the page file / swap file).
    The algorithms that control this are critical to the system performance.

    Consider that some pages of code in a running programme are executed only
    once (e.g. at startup). It is wasteful to keep these in RAM when they will
    never be needed again. On the other hand, a programme that is accessing
    the disk a lot (especially in random access mode) can benefit from disk
    caching of frequently/recently accessed disk blocks.

    If you run without a page file (or swap file) you can limit the OS's
    ability to efficiently allocate disk buffers and cache space.

    The following link provides more information on this topic ....

    http://rudd-o.com/archives/2006/01/11/why-swap-is-good-even-with-tons-of-ram/
     
    Murray Symon, Jan 29, 2006
    #16
  17. Nathan  Mercer

    S Roby Guest

    In article <%iICf.49115$>, David <> wrote:
    >S Roby wrote:
    >> In article <>, XP

    > <> wrote:
    >>> On Thu, 26 Jan 2006 10:12:12 GMT, le (S Roby) wrote:
    >>>
    >>>> I'm running XP with 1G of RAM
    >>>> So why have I got 129M of pagefile usage??
    >>>
    >>>
    >>>
    >>> Far to low it should use all that is Free.
    >>>
    >>> I have set mine to 500megs as it was up in the gig range
    >>>
    >>>

    >>
    >> Mine is set to 500M
    >> 129M is being used

    >
    >Not necessarily used, 129M is 'claimed'. Processes have allocated
    >memory, but windows doesn't know if that memory will be used or not, so
    >it has been assigned to the pagefile. When it is actually used it will
    >be in RAM unless the RAM is full (in which case stuff will be moved from
    >the pagefile to RAM and vice versa in a crazy manner causing your
    >harddrive to make awful noises)


    Back in Win 3.1 (& win95) i used to wonder about Win using the HD (pagefile)
    to simulate real ram & then using RAM to to cache the HD. Bit if a vicious
    circle.
     
    S Roby, Jan 29, 2006
    #17
  18. On Sun, 29 Jan 2006 01:31:52 GMT, le (S Roby) wrote:

    >In article <%iICf.49115$>, David <> wrote:
    >>S Roby wrote:
    >>> In article <>, XP

    >> <> wrote:
    >>>> On Thu, 26 Jan 2006 10:12:12 GMT, le (S Roby) wrote:
    >>>>
    >>>>> I'm running XP with 1G of RAM
    >>>>> So why have I got 129M of pagefile usage??
    >>>>
    >>>>
    >>>>
    >>>> Far to low it should use all that is Free.
    >>>>
    >>>> I have set mine to 500megs as it was up in the gig range
    >>>>
    >>>>
    >>>
    >>> Mine is set to 500M
    >>> 129M is being used

    >>
    >>Not necessarily used, 129M is 'claimed'. Processes have allocated
    >>memory, but windows doesn't know if that memory will be used or not, so
    >>it has been assigned to the pagefile. When it is actually used it will
    >>be in RAM unless the RAM is full (in which case stuff will be moved from
    >>the pagefile to RAM and vice versa in a crazy manner causing your
    >>harddrive to make awful noises)

    >
    >Back in Win 3.1 (& win95) i used to wonder about Win using the HD (pagefile)
    >to simulate real ram & then using RAM to to cache the HD. Bit if a vicious
    >circle.


    Sane operating systems do not use the data file cache to cache the
    paging store! In this respect, even Windows is sane.

    The allocation of RAM to caching of data files is a fraught business -
    no one scheme suits all types of usage of a system, and your pattern
    of usage can change frequently enough that if you tune your system to
    handle what you are doing today, it will run very slowly with what you
    are doing tomorrow. So most data file caching algorithms are very
    generalised and not terribly efficient, but also not terribly
    inefficient.
     
    Stephen Worthington, Jan 29, 2006
    #18
  19. Nathan  Mercer

    S Roby Guest


    >>>Not necessarily used, 129M is 'claimed'. Processes have allocated memory,
    >>>but windows doesn't know if that memory will be used or not, so it has
    >>>been assigned to the pagefile. When it is actually used it will be in RAM
    >>>unless the RAM is full (in which case stuff will be moved from the
    >>>pagefile to RAM and vice versa in a crazy manner causing your harddrive
    >>>to make awful noises)

    >>
    >> Back in Win 3.1 (& win95) i used to wonder about Win using the HD
    >> (pagefile) to simulate real ram & then using RAM to to cache the HD. Bit
    >> if a vicious circle.

    >
    >It can be, but only if not managed properly. This may have been the problem
    >with early Windows (prior to NT). I seem to recall problems even with
    >Windows 95 being too aggressive with its allocation of RAm for disk caching.
    >


    Biggist issue was MS giving unrealistic min RAM spec for WIN
    Was it 4M? for Win95a
    16M? for Win98
     
    S Roby, Jan 29, 2006
    #19
  20. Nathan  Mercer

    Dave Doe Guest

    In article <PIjCf.28956$>, le
    says...
    > In article <>, Dave Doe <> wrote:
    > >In article <Fn0Cf.22791$>, le
    > >says...
    > >> I'm running XP with 1G of RAM
    > >> So why have I got 129M of pagefile usage??

    > >
    > >Shouldn't you have your pagefile settings at:
    > >1536/1536
    > >
    > >IIRC MS recommend 1.5 x RAM.

    >
    >
    > Doesnt this go back to the old days of Win3.1 when 8M was alot of RAM


    Applies to W2K, W2K Server. Not sure on later OS's.

    --
    Duncan
     
    Dave Doe, Jan 31, 2006
    #20
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