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Thread: Memory allocation limits for applications on x86 systems

  1. #1
    Join Date
    Apr 2010
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    80

    Memory allocation limits for applications on x86 systems

    I have done many basic programs in Java. Now I have given an assignment to check the memory allocation limits for an applications. I have googled it but didn't find any satisfactory solutions for it. So thought that you members can help me in fixing this issue. Please provide some detailed information about the memory allocation limits. I think that you must have got the point that I want to tell. I am waiting for your responses.

  2. #2
    Join Date
    Dec 2008
    Posts
    183

    Re: Memory allocation limits for applications on x86 systems

    Solaris applications to assign memory by functions such as malloc (), Brk () or mmap), use. The amount of memory that an application can assign a maximum, is the size of the virtual user address space limited. Program text-stack, data, and libraries that are in the virtual Users are able to address space, the size of the maximum possible Additionally reduce memory allocation.

  3. #3
    Join Date
    Dec 2008
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    202

    Re: Memory allocation limits for applications on x86 systems

    In a 32-bit computing environment, the virtual 32-bit address space User and kernel shared. Consequently, the size of the user virtual address space is 4 GB minus the size of the virtual Kernel address space. The configuration of the size of the kernel virtual address space depends on the size of physical RAM from. With increasing size of the physical memory will reduce the size of the user address space. At Systems with 8 GB of RAM is the size of the user address space is about 3 GB.

  4. #4
    Join Date
    Mar 2008
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    258

    Re: Memory allocation limits for applications on x86 systems

    If the limits of memory allocation for an application not for sufficient, you have two options :
    • Reduce the default size of the kernel virtual address space to the user virtual address space to expand. You can kernelbase the variable the eeprom command to a higher value contact. Go to the Amendment of kernelbase very carefully before. Otherwise, a system with a smaller kernel virtual address space to stand or less efficient run as before.
    • A cheaper alternative is to run the application in the Solaris x86 64-bit computing environment.

  5. #5
    Join Date
    Mar 2008
    Posts
    227

    Re: Memory allocation limits for applications on x86 systems

    In the 64-bit computing environment is the virtual address space for 32-bit applications fully available to the user. Therefore, a -Bit application, the full 4 GB assign 32, minus the User address space, which, stack and libraries required for any text. Some older 64-bit AMD processors, the limit for the Memory allocation for another GB to be reduced.

  6. #6
    Join Date
    Mar 2008
    Posts
    192

    Re: Memory allocation limits for applications on x86 systems

    To determine whether your Processor is affected, perform the following steps :
    • Run the command pmap $ $ from an arbitrary 32-bit shell.
    • Check in the process overview that addresses are listed, larger than or are equal to 0xC0000000. If these addresses do not exist, limited the Solaris OS 32-bit applications on the lower 3 GB of virtual.

  7. #7
    Join Date
    Jul 2006
    Posts
    289

    Re: Memory allocation limits for applications on x86 systems

    Solaris 10 on x86 supports the no execute (NX) bit in the Modes 32-bit and 64-bit. The NX bit enables the full implementation of safeguards, the implied if PROT_EXEC in different memory system calls, such as the Mmap () function used is not. Previously, on x86 at all, associated Memory always set PROT_EXEC implication. Through the support of Solaris for the NX bit is improved virus protection.

  8. #8
    Join Date
    Aug 2006
    Posts
    235

    Re: Memory allocation limits for applications on x86 systems

    On NX-capable hardware bit Solaris OS uses the NX by default when PROT_EXEC is not specified. Stack segments, however, use default PROT_EXEC, not the NX-bit. The default setting for stack segments may be replaced by one of the following are changed:
    • Set no_exec_userstack in / etc / system so tight that no global exec Application stack is set for all.
    • Join a single application with the mapping file / Usr / lib / ld / map.noexstk.

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