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Thread safety of vm_copy - Mac Programming

I tried looking around for explicit doentation on this but to no avail, perhaps it is too basic. On Mac OS X the Mach function vm_copy has a copy-on-write optimization, but is it thread-safe? For example, suppose I have memory A that is vm_copy over to memory B. Then thread 1 writes to it at the same time as thread 2 writing to it. Does the OS do the right thing and allow one of the threads to experience the copy and see the copied memory, and the other thread the original memory? i.e. does the OS serialize access to ...

  1. #1

    Default Thread safety of vm_copy

    I tried looking around for explicit doentation on this but to no
    avail, perhaps it is too basic. On Mac OS X the Mach function vm_copy
    has a copy-on-write optimization, but is it thread-safe?

    For example, suppose I have memory A that is vm_copy over to memory B.
    Then thread 1 writes to it at the same time as thread 2 writing to it.
    Does the OS do the right thing and allow one of the threads to
    experience the copy and see the copied memory, and the other thread
    the original memory? i.e. does the OS serialize access to the shared
    memory in order to unshare it, or do I have to explicitly serialize
    access with a mutex or similar mechanism?
    Glen Low Guest

  2. #2

    Default Re: Thread safety of vm_copy

    > It has to be.

    Is there any explicit doentation (by Next, Apple, BSD) on it?
    Glen Low Guest

  3. #3

    Default Re: Thread safety of vm_copy

    [email]glenlowpixelglow.com[/email] (Glen Low) wrote in message news:<9215d7ac.0307192242.7ac9ab50posting.google. com>...
    > > It has to be.
    >
    > Is there any explicit doentation (by Next, Apple, BSD) on it?
    Not really. There's a book "Programming under Mach," by Boykin,
    Kirschen, Langerman, and LoVerso. It's out of print, but a good read
    if you can get a copy.
    Lally Singh Guest

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