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authorPaul E. McKenney <paulmck@linux.vnet.ibm.com>2014-06-12 13:30:25 -0700
committerPaul E. McKenney <paulmck@linux.vnet.ibm.com>2014-07-09 09:15:01 -0700
commitabaa93d9e1de2c29297e69ddba8ddd38f15064cf (patch)
tree127f64c80be6f30fed7265d42cbfc5b449853618 /kernel/rcu/tree.h
parent48bd8e9b82a750b983823f391c67e70553757afa (diff)
downloadblackbird-op-linux-abaa93d9e1de2c29297e69ddba8ddd38f15064cf.tar.gz
blackbird-op-linux-abaa93d9e1de2c29297e69ddba8ddd38f15064cf.zip
rcu: Simplify priority boosting by putting rt_mutex in rcu_node
RCU priority boosting currently checks for boosting via a pointer in task_struct. However, this is not needed: As Oleg noted, if the rt_mutex is placed in the rcu_node instead of on the booster's stack, the boostee can simply check it see if it owns the lock. This commit makes this change, shrinking task_struct by one pointer and the kernel by thirteen lines. Suggested-by: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Diffstat (limited to 'kernel/rcu/tree.h')
-rw-r--r--kernel/rcu/tree.h3
1 files changed, 3 insertions, 0 deletions
diff --git a/kernel/rcu/tree.h b/kernel/rcu/tree.h
index 3eeb919e26a2..60fb0eaa2d16 100644
--- a/kernel/rcu/tree.h
+++ b/kernel/rcu/tree.h
@@ -177,6 +177,9 @@ struct rcu_node {
/* to carry out the boosting is fully */
/* released with no future boostee accesses */
/* before that rt_mutex is re-initialized. */
+ struct rt_mutex boost_mtx;
+ /* Used only for the priority-boosting */
+ /* side effect, not as a lock. */
unsigned long boost_time;
/* When to start boosting (jiffies). */
struct task_struct *boost_kthread_task;
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