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    SubjectRe: virtual cache, TLB, and OS
    xu feng wrote:
    > I am just confused about the author:
    > 1- first point, why the cache has to be bothered by
    > the change in the address logical-physical mapping
    > since it is a virtual cache??
    >

    If you:

    1. mmap file A at virtual address X
    2. use memory at X
    3. mmap file B at X
    4. look at X

    If its a virtual cache, and it wasn't flushed at step 3, then step 4
    will see A's contents rather than B's.

    > 2- could you please give me a situation where two
    > virtual addresses from the same process are mapped to
    > the same physical address?
    >
    > i can't see this happening since each process page is
    > allocated a dedicated frame.
    >

    If you mmap a file multiple times, then the kernel will assign multiple
    different virtual addresses for the same page cache page(s).


    J
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