lkml.org 
[lkml]   [2006]   [Jan]   [25]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    From
    SubjectRe: [PATCH/RFC] Shared page tables
    Date
    Dave,

    Here's another one to keep you awake at night:

    mmap a shared, anonymous region of 8MB (2MB aligned), and fork off some
    children (4 is good enough for me). In each child, munmap() a 2 MB portion
    of the shared region (starting at offset 2MB in the shared region) and then
    mmap() a private, anonymous region in its place. Have each child store some
    unique data in that region, sleep for a bit and then go look to see if its
    data is still there.

    Under 2.6.15, this works just fine. Under 2.6.15 + shpt patch, each child
    still points at the shared region and steps on the data of the other
    children.

    I imagine the above gets even more interesting if the offset or length of the
    unmapped region is not a multiple of the 2MB alignment.

    All of these test cases are for Opteron. Your alignment may vary.

    (Sorry about this... )

    --
    Ray Bryant
    AMD Performance Labs Austin, Tx
    512-602-0038 (o) 512-507-7807 (c)

    -
    To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
    the body of a message to majordomo@vger.kernel.org
    More majordomo info at http://vger.kernel.org/majordomo-info.html
    Please read the FAQ at http://www.tux.org/lkml/

    \
     
     \ /
      Last update: 2006-01-26 01:19    [W:0.021 / U:0.368 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site