Commit-ID: b6331ae8afe4118884c4b6e14a213758d88422b2
Gitweb: http://git.kernel.org/tip/b6331ae8afe4118884c4b6e14a213758d88422b2
Author: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
AuthorDate: Sat, 4 Oct 2014 03:43:41 -0700
Committer: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
CommitDate: Thu, 13 Nov 2014 10:35:39 -0800
rcu: Optimize cond_resched_rcu_qs()
The current implementation of cond_resched_rcu_qs() can invoke
rcu_note_voluntary_context_switch() twice in the should_resched()
case, once via the call to __schedule() and once directly. However, as
noted by Joe Lawrence in a patch to the team subsystem, cond_resched()
returns an indication as to whether or not the call to __schedule()
actually happened. This commit therefore changes cond_resched_rcu_qs()
so as to invoke rcu_note_voluntary_context_switch() only when __schedule()
was not called.
Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
---
include/linux/rcupdate.h | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h
index a033d8b..36ea3ba 100644
--- a/include/linux/rcupdate.h
+++ b/include/linux/rcupdate.h
@@ -348,8 +348,8 @@ extern struct srcu_struct tasks_rcu_exit_srcu;
*/
#define cond_resched_rcu_qs() \
do { \
- rcu_note_voluntary_context_switch(current); \
- cond_resched(); \
+ if (!cond_resched()) \
+ rcu_note_voluntary_context_switch(current); \
} while (0)
#if defined(CONFIG_DEBUG_LOCK_ALLOC) || defined(CONFIG_RCU_TRACE) || defined(CONFIG_SMP)
--
To unsubscribe from this list: send the line "unsubscribe linux-tip-commits" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
|