Eric Lee / smarc-fsl-linux-kernel

30 Nov, 2010

3 commits

  • e940cc804   rcu: Distinguish between boosting and boosted ... Browse Code »

    RCU priority boosting's tracing did not distinguish between ongoing
    boosting and completion of boosting. This commit therefore adds this
    capability.

    Signed-off-by: Paul E. McKenney
    Signed-off-by: Paul E. McKenney

    Paul E. McKenney
     
  • 9e571a82f   rcu: add tracing for TINY_RCU and TINY_PREEMPT_RCU ... Browse Code »

    Add tracing for the tiny RCU implementations, including statistics on
    boosting in the case of TINY_PREEMPT_RCU and RCU_BOOST.

    Signed-off-by: Paul E. McKenney
    Signed-off-by: Paul E. McKenney

    Paul E. McKenney
     
  • 24278d148   rcu: priority boosting for TINY_PREEMPT_RCU ... Browse Code »

    Add priority boosting, but only for TINY_PREEMPT_RCU. This is enabled
    by the default-off RCU_BOOST kernel parameter. The priority to which to
    boost preempted RCU readers is controlled by the RCU_BOOST_PRIO kernel
    parameter (defaulting to real-time priority 1) and the time to wait
    before boosting the readers blocking a given grace period is controlled
    by the RCU_BOOST_DELAY kernel parameter (defaulting to 500 milliseconds).

    Signed-off-by: Paul E. McKenney
    Signed-off-by: Paul E. McKenney

    Paul E. McKenney
     

18 Nov, 2010

1 commit

  • b2c0710c4   rcu: move TINY_RCU from softirq to kthread ... Browse Code »

    If RCU priority boosting is to be meaningful, callback invocation must
    be boosted in addition to preempted RCU readers. Otherwise, in presence
    of CPU real-time threads, the grace period ends, but the callbacks don't
    get invoked. If the callbacks don't get invoked, the associated memory
    doesn't get freed, so the system is still subject to OOM.

    But it is not reasonable to priority-boost RCU_SOFTIRQ, so this commit
    moves the callback invocations to a kthread, which can be boosted easily.

    Signed-off-by: Paul E. McKenney
    Signed-off-by: Paul E. McKenney

    Paul E. McKenney
     

28 Aug, 2010

1 commit

21 Aug, 2010

1 commit

20 Aug, 2010

1 commit

  • a57eb940d   rcu: Add a TINY_PREEMPT_RCU ... Browse Code »

    Implement a small-memory-footprint uniprocessor-only implementation of
    preemptible RCU. This implementation uses but a single blocked-tasks
    list rather than the combinatorial number used per leaf rcu_node by
    TREE_PREEMPT_RCU, which reduces memory consumption and greatly simplifies
    processing. This version also takes advantage of uniprocessor execution
    to accelerate grace periods in the case where there are no readers.

    The general design is otherwise broadly similar to that of TREE_PREEMPT_RCU.

    This implementation is a step towards having RCU implementation driven
    off of the SMP and PREEMPT kernel configuration variables, which can
    happen once this implementation has accumulated sufficient experience.

    Removed ACCESS_ONCE() from __rcu_read_unlock() and added barrier() as
    suggested by Steve Rostedt in order to avoid the compiler-reordering
    issue noted by Mathieu Desnoyers (http://lkml.org/lkml/2010/8/16/183).

    As can be seen below, CONFIG_TINY_PREEMPT_RCU represents almost 5Kbyte
    savings compared to CONFIG_TREE_PREEMPT_RCU. Of course, for non-real-time
    workloads, CONFIG_TINY_RCU is even better.

    CONFIG_TREE_PREEMPT_RCU

    text data bss dec filename
    13 0 0 13 kernel/rcupdate.o
    6170 825 28 7023 kernel/rcutree.o
    ----
    7026 Total

    CONFIG_TINY_PREEMPT_RCU

    text data bss dec filename
    13 0 0 13 kernel/rcupdate.o
    2081 81 8 2170 kernel/rcutiny.o
    ----
    2183 Total

    CONFIG_TINY_RCU (non-preemptible)

    text data bss dec filename
    13 0 0 13 kernel/rcupdate.o
    719 25 0 744 kernel/rcutiny.o
    ---
    757 Total

    Requested-by: Loïc Minier
    Signed-off-by: Paul E. McKenney

    Paul E. McKenney
     

11 May, 2010

1 commit