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    Subject[PATCH tip/core/rcu 2/2] rcu: Allow TREE_PREEMPT_RCU on UP systems
    From: "Paul E. McKenney" <>

    The TINY_PREEMPT_RCU is complex, does not provide that much memory
    savings, and therefore TREE_PREEMPT_RCU should be used instead. The
    systems where the difference between TINY_PREEMPT_RCU and TREE_PREEMPT_RCU
    are quite small compared to the memory footprint of CONFIG_PREEMPT.

    This commit therefore takes a first step towards eliminating
    TINY_PREEMPT_RCU by allowing TREE_PREEMPT_RCU to be configured on !SMP

    Signed-off-by: Paul E. McKenney <>
    init/Kconfig | 4 +++-
    1 files changed, 3 insertions(+), 1 deletions(-)

    diff --git a/init/Kconfig b/init/Kconfig
    index a5e90e1..fb19b46 100644
    --- a/init/Kconfig
    +++ b/init/Kconfig
    @@ -453,7 +453,7 @@ config TREE_RCU

    bool "Preemptible tree-based hierarchical RCU"
    - depends on PREEMPT && SMP
    + depends on PREEMPT
    This option selects the RCU implementation that is
    designed for very large SMP systems with hundreds or
    @@ -461,6 +461,8 @@ config TREE_PREEMPT_RCU
    is also required. It also scales down nicely to
    smaller systems.

    + Select this option if you are unsure.
    config TINY_RCU
    bool "UP-only small-memory-footprint RCU"
    depends on !PREEMPT && !SMP

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      Last update: 2013-01-27 06:41    [W:0.024 / U:39.664 seconds]
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