diff options
| author | Paul E. McKenney <paulmck@linux.vnet.ibm.com> | 2009-09-13 20:15:10 +0400 |
|---|---|---|
| committer | Ingo Molnar <mingo@elte.hu> | 2009-09-18 02:06:33 +0400 |
| commit | c3422bea5f09b0e85704f51f2b01271630b8940b (patch) | |
| tree | fc4a18241b0f7f5d71211f6787428197769cb9f5 /include/linux/sched.h | |
| parent | b0e165c035b13e1074fa0b555318bd9cb7102558 (diff) | |
| download | linux-c3422bea5f09b0e85704f51f2b01271630b8940b.tar.xz | |
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/sched.h')
| -rw-r--r-- | include/linux/sched.h | 1 |
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); #define RCU_READ_UNLOCK_BLOCKED (1 << 0) /* blocked while in RCU read-side. */ #define RCU_READ_UNLOCK_NEED_QS (1 << 1) /* RCU core needs CPU response. */ -#define RCU_READ_UNLOCK_GOT_QS (1 << 2) /* CPU has responded to RCU core. */ static inline void rcu_copy_process(struct task_struct *p) { |