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    Subject[GIT PULL][PATCH 0/7] Reduce timekeeping lock hold time
    Here is the second half of the timekeeping cleanups (the first
    half are already in -tip) as well as some changes to reduce the
    timekeeping lock hold times.

    This work grew out of some of Eric Dumazet's and Thomas Gleixner's
    suggestions, after they noticed the xtime_lock hold time could be
    on the long side.

    The basic idea is that we keep a shadow copy of the timekeeper
    stucture, which can be updated while readers are accessing the
    time. Then we only have to block readers as we switch to the
    newly updated structure.

    I've done some limited testing, but it would be good to get
    this in -tip early, so we can be sure it gets enough testing
    before 3.4 is released.

    CC: Thomas Gleixner <>
    CC: Eric Dumazet <>
    CC: Richard Cochran <>



    These patches are available in the git repository at:
    git:// fortglx/3.4/time

    John Stultz (7):
    time: Condense timekeeper.xtime into xtime_sec
    time: Rework timekeeping functions to take timekeeper ptr as argument
    time: Split timekeeper lock into separate reader/writer locks
    time: Update timekeeper structure using a local shadow
    time: Shadow cycle_last in timekeeper structure
    time: Reduce timekeeper read lock hold time
    time: Convert the timekeeper's wlock to a raw_spin_lock

    kernel/time/timekeeping.c | 414 ++++++++++++++++++++++++++-------------------
    1 files changed, 243 insertions(+), 171 deletions(-)


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