memory limit on x64

Discussion in 'Windows 64bit' started by news.microsoft.com, Jun 22, 2005.

  1. Are 32 bit apps still limited to 3g per process on x64 systems? What about
    64 bit apps? Whats the limit per process?

    THanks,
    KG
     
    news.microsoft.com, Jun 22, 2005
    #1
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  2. 32 bit applications are limited to 4GB if they are compiled with the
    /LARGEMEMORYADDRESSAWARE flag (which was required to get 3GB under 32-bit
    Windows). No command line switches or other application changes are required
    to give that 4gb, assuming the application was written to recognize the extra
    memory at all.

    64-bit processes have access to 8TB of virtual memory address space.


    --
    Charlie.
    http://www.msmvps.com/xperts64/


    news.microsoft.com wrote:
    > Are 32 bit apps still limited to 3g per process on x64 systems? What
    > about 64 bit apps? Whats the limit per process?
    >
    > THanks,
    > KG
     
    Charlie Russel - MVP, Jun 22, 2005
    #2
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  3. news.microsoft.com

    John Barnes Guest

    Is there a technical advantage NOT to use the /LARGEMEMORYADDRESSAWARE
    flag. I have a lot of programs which obviously don't have it set. Seems
    strange a $200 program wouldn't have it set. Maybe just laziness when
    upgrading from old versions.


    "Charlie Russel - MVP" <> wrote in message
    news:e$...
    > 32 bit applications are limited to 4GB if they are compiled with the fla
    > /LARGEMEMORYADDRESSAWARE g (which was required to get 3GB under 32-bit
    > Windows). No command line switches or other application changes are
    > required to give that 4gb, assuming the application was written to
    > recognize the extra memory at all.
    >
    > 64-bit processes have access to 8TB of virtual memory address space.
    >
    >
    > --
    > Charlie.
    > http://www.msmvps.com/xperts64/
    >
    >
    > news.microsoft.com wrote:
    >> Are 32 bit apps still limited to 3g per process on x64 systems? What
    >> about 64 bit apps? Whats the limit per process?
    >>
    >> THanks,
    >> KG

    >
    >
     
    John Barnes, Jun 22, 2005
    #3
  4. Probably laziness, but I'm not enough of a programmer to know. OTOH, there
    can be good reasons to NOT run 32-bit Windows with the boot time /3GB switch
    (which is required in 32-bit windows to make the extra memory available to
    applications). Using this switch severely constrains the available memory for
    the OS and can be a big problem with an I/O intensive system. So you might
    well do it on a SQL Server or Exchange box, that is doing nothing else, and
    where the application is basically handling the I/O. But no way on a terminal
    server box, for example, or a file server.

    --
    Charlie.
    http://www.msmvps.com/xperts64/


    John Barnes wrote:
    > Is there a technical advantage NOT to use the /LARGEMEMORYADDRESSAWARE
    > flag. I have a lot of programs which
    > obviously don't have it set. Seems strange a $200 program wouldn't
    > have it set. Maybe just laziness when upgrading from old versions.
    >
    >
    > "Charlie Russel - MVP" <> wrote in
    > message news:e$...
    >> 32 bit applications are limited to 4GB if they are compiled with the
    >> fla /LARGEMEMORYADDRESSAWARE g (which was required to get 3GB under
    >> 32-bit Windows). No command line switches or other application
    >> changes are required to give that 4gb, assuming the application was
    >> written to recognize the extra memory at all.
    >>
    >> 64-bit processes have access to 8TB of virtual memory address space.
    >>
    >>
    >> --
    >> Charlie.
    >> http://www.msmvps.com/xperts64/
    >>
    >>
    >> news.microsoft.com wrote:
    >>> Are 32 bit apps still limited to 3g per process on x64 systems? What
    >>> about 64 bit apps? Whats the limit per process?
    >>>
    >>> THanks,
    >>> KG
     
    Charlie Russel - MVP, Jun 22, 2005
    #4
  5. ACTUALLY, Win XP x86 can only access 128GB in this release using native
    64bit apps.


    "Charlie Russel - MVP" <> wrote in message
    news:e$...
    > 32 bit applications are limited to 4GB if they are compiled with the
    > /LARGEMEMORYADDRESSAWARE flag (which was required to get 3GB under 32-bit
    > Windows). No command line switches or other application changes are
    > required to give that 4gb, assuming the application was written to
    > recognize the extra memory at all.
    >
    > 64-bit processes have access to 8TB of virtual memory address space.
    >
    >
    > --
    > Charlie.
    > http://www.msmvps.com/xperts64/
    >
    >
    > news.microsoft.com wrote:
    >> Are 32 bit apps still limited to 3g per process on x64 systems? What
    >> about 64 bit apps? Whats the limit per process?
    >>
    >> THanks,
    >> KG

    >
    >
     
    Draco Paladine, Jun 23, 2005
    #5
  6. Read carefully before you yell about something. I said 8TB of virtual memory
    address space. That is correct. It will only support 128 GB of physical RAM
    (in XP - Server is different). RAM and virtual memory address space are NOT
    the same thing. (and it x64, not x86, BTW.)

    the issue for many applications has not been RAM but virtual memory address
    space, which is limited to 4GB total for 32-bit Windows without some
    interesting workarounds. Of that 4GB of virtual memory address space,
    normally 2GB is reserved for the OS itself, with the other 2gb available for
    applications. If the application is written to take advantage of it, then you
    can constrain the OS into 1GB, leaving 3GB of virtual memory address space
    for application processes. But many applications are not written to take
    advantage, and they will only ever see 2gb of virtual memory address space.


    --
    Charlie.
    http://www.msmvps.com/xperts64/


    Draco Paladine wrote:
    > ACTUALLY, Win XP x86 can only access 128GB in this release using
    > native 64bit apps.
    >
    >
    > "Charlie Russel - MVP" <> wrote in
    > message news:e$...
    >> 32 bit applications are limited to 4GB if they are compiled with the
    >> /LARGEMEMORYADDRESSAWARE flag (which was required to get 3GB under
    >> 32-bit Windows). No command line switches or other application
    >> changes are required to give that 4gb, assuming the application was
    >> written to recognize the extra memory at all.
    >>
    >> 64-bit processes have access to 8TB of virtual memory address space.
    >>
    >>
    >> --
    >> Charlie.
    >> http://www.msmvps.com/xperts64/
    >>
    >>
    >> news.microsoft.com wrote:
    >>> Are 32 bit apps still limited to 3g per process on x64 systems? What
    >>> about 64 bit apps? Whats the limit per process?
    >>>
    >>> THanks,
    >>> KG
     
    Charlie Russel - MVP, Jun 24, 2005
    #6
  7. news.microsoft.com

    kevin goff Guest

    What about the .net framework 1.1. Anyone know if that will give me any
    more memory usage by switching to x64? I know the 2.0 framework is supposed
    to but it wont be out for a few months.
    KG

    "Draco Paladine" <> wrote in message
    news:...
    > ACTUALLY, Win XP x86 can only access 128GB in this release using native
    > 64bit apps.
    >
    >
    > "Charlie Russel - MVP" <> wrote in message
    > news:e$...
    >> 32 bit applications are limited to 4GB if they are compiled with the
    >> /LARGEMEMORYADDRESSAWARE flag (which was required to get 3GB under 32-bit
    >> Windows). No command line switches or other application changes are
    >> required to give that 4gb, assuming the application was written to
    >> recognize the extra memory at all.
    >>
    >> 64-bit processes have access to 8TB of virtual memory address space.
    >>
    >>
    >> --
    >> Charlie.
    >> http://www.msmvps.com/xperts64/
    >>
    >>
    >> news.microsoft.com wrote:
    >>> Are 32 bit apps still limited to 3g per process on x64 systems? What
    >>> about 64 bit apps? Whats the limit per process?
    >>>
    >>> THanks,
    >>> KG

    >>
    >>

    >
    >
     
    kevin goff, Jul 15, 2005
    #7
  8. yes. 32-bit applications compiled to take advantage of virtual memory address
    space beyond 2GB will see a full 4GB under WOW64. See my Deployment
    whitepaper at
    http://www.microsoft.com/windowsserver2003/64bit/x64/deploy.mspx. And the
    Benefits one as well.

    --
    Please, all replies to the newsgroup.
    ======================
    Charlie.
    http://www.msmvps.com/xperts64/


    kevin goff wrote:
    > What about the .net framework 1.1. Anyone know if that will give me
    > any more memory usage by switching to x64? I know the 2.0 framework
    > is supposed to but it wont be out for a few months.
    > KG
    >
    > "Draco Paladine" <> wrote in message
    > news:...
    >> ACTUALLY, Win XP x86 can only access 128GB in this release using
    >> native 64bit apps.
    >>
    >>
    >> "Charlie Russel - MVP" <> wrote in
    >> message news:e$...
    >>> 32 bit applications are limited to 4GB if they are compiled with the
    >>> /LARGEMEMORYADDRESSAWARE flag (which was required to get 3GB under
    >>> 32-bit Windows). No command line switches or other application
    >>> changes are required to give that 4gb, assuming the application was
    >>> written to recognize the extra memory at all.
    >>>
    >>> 64-bit processes have access to 8TB of virtual memory address space.
    >>>
    >>>
    >>> --
    >>> Charlie.
    >>> http://www.msmvps.com/xperts64/
    >>>
    >>>
    >>> news.microsoft.com wrote:
    >>>> Are 32 bit apps still limited to 3g per process on x64 systems? What
    >>>> about 64 bit apps? Whats the limit per process?
    >>>>
    >>>> THanks,
    >>>> KG
     
    Charlie Russel - MVP, Jul 18, 2005
    #8
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