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authorPaul E. McKenney <paulmck@linux.vnet.ibm.com>2009-09-13 12:15:10 -0400
committerIngo Molnar <mingo@elte.hu>2009-09-17 18:06:33 -0400
commitc3422bea5f09b0e85704f51f2b01271630b8940b (patch)
treefc4a18241b0f7f5d71211f6787428197769cb9f5 /include/linux
parentb0e165c035b13e1074fa0b555318bd9cb7102558 (diff)
rcu: Simplify rcu_read_unlock_special() quiescent-state accounting
The earlier approach required two scheduling-clock ticks to note an preemptable-RCU quiescent state in the situation in which the scheduling-clock interrupt is unlucky enough to always interrupt an RCU read-side critical section. With this change, the quiescent state is instead noted by the outermost rcu_read_unlock() immediately following the first scheduling-clock tick, or, alternatively, by the first subsequent context switch. Therefore, this change also speeds up grace periods. Suggested-by: Josh Triplett <josh@joshtriplett.org> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: laijs@cn.fujitsu.com Cc: dipankar@in.ibm.com Cc: akpm@linux-foundation.org Cc: mathieu.desnoyers@polymtl.ca Cc: dvhltc@us.ibm.com Cc: niv@us.ibm.com Cc: peterz@infradead.org Cc: rostedt@goodmis.org Cc: Valdis.Kletnieks@vt.edu LKML-Reference: <12528585111945-git-send-email-> Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'include/linux')
-rw-r--r--include/linux/sched.h1
1 files changed, 0 insertions, 1 deletions
diff --git a/include/linux/sched.h b/include/linux/sched.h
index f3d74bd04d18..c62a9f84d614 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1740,7 +1740,6 @@ extern cputime_t task_gtime(struct task_struct *p);
1740 1740
1741#define RCU_READ_UNLOCK_BLOCKED (1 << 0) /* blocked while in RCU read-side. */ 1741#define RCU_READ_UNLOCK_BLOCKED (1 << 0) /* blocked while in RCU read-side. */
1742#define RCU_READ_UNLOCK_NEED_QS (1 << 1) /* RCU core needs CPU response. */ 1742#define RCU_READ_UNLOCK_NEED_QS (1 << 1) /* RCU core needs CPU response. */
1743#define RCU_READ_UNLOCK_GOT_QS (1 << 2) /* CPU has responded to RCU core. */
1744 1743
1745static inline void rcu_copy_process(struct task_struct *p) 1744static inline void rcu_copy_process(struct task_struct *p)
1746{ 1745{