Commit-ID: 07f27570dcd148a5f4de7dc3513c1d1cd069b362
Gitweb: https://git.kernel.org/tip/07f27570dcd148a5f4de7dc3513c1d1cd069b362
Author: Byungchul Park <byungchul.park@xxxxxxx>
AuthorDate: Fri, 11 May 2018 17:30:34 +0900
Committer: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
CommitDate: Thu, 12 Jul 2018 15:39:12 -0700
rcu: Improve rcu_note_voluntary_context_switch() reporting
We expect a quiescent state of TASKS_RCU when cond_resched_tasks_rcu_qs()
is called, no matter whether it actually be scheduled or not. However,
it currently doesn't report the quiescent state when the task enters
into __schedule() as it's called with preempt = true. So make it report
the quiescent state unconditionally when cond_resched_tasks_rcu_qs() is
called.
And in TINY_RCU, even though the quiescent state of rcu_bh also should
be reported when the tick interrupt comes from user, it doesn't. So make
it reported.
Lastly in TREE_RCU, rcu_note_voluntary_context_switch() should be
reported when the tick interrupt comes from not only user but also idle,
as an extended quiescent state.
Signed-off-by: Byungchul Park <byungchul.park@xxxxxxx>
Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
[ paulmck: Simplify rcutiny portion given no RCU-tasks for !PREEMPT. ]
---
include/linux/rcupdate.h | 4 ++--
kernel/rcu/tiny.c | 4 +---
kernel/rcu/tree.c | 4 ++--
3 files changed, 5 insertions(+), 7 deletions(-)
diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h
index 67ec077c7ee5..5cab15e7ec83 100644
--- a/include/linux/rcupdate.h
+++ b/include/linux/rcupdate.h
@@ -194,8 +194,8 @@ static inline void exit_tasks_rcu_finish(void) { }
*/
#define cond_resched_tasks_rcu_qs() \
do { \
- if (!cond_resched()) \
- rcu_note_voluntary_context_switch_lite(current); \
+ rcu_note_voluntary_context_switch_lite(current); \
+ cond_resched(); \
} while (0)
/*
diff --git a/kernel/rcu/tiny.c b/kernel/rcu/tiny.c
index a64eee0db39e..befc9321a89c 100644
--- a/kernel/rcu/tiny.c
+++ b/kernel/rcu/tiny.c
@@ -122,10 +122,8 @@ void rcu_check_callbacks(int user)
{
if (user)
rcu_sched_qs();
- else if (!in_softirq())
+ if (user || !in_softirq())
rcu_bh_qs();
- if (user)
- rcu_note_voluntary_context_switch(current);
}
/*
diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index d3333ee2c6f5..19beabe73629 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -2645,6 +2645,7 @@ void rcu_check_callbacks(int user)
rcu_sched_qs();
rcu_bh_qs();
+ rcu_note_voluntary_context_switch(current);
} else if (!in_softirq()) {
@@ -2660,8 +2661,7 @@ void rcu_check_callbacks(int user)
rcu_preempt_check_callbacks();
if (rcu_pending())
invoke_rcu_core();
- if (user)
- rcu_note_voluntary_context_switch(current);
+
trace_rcu_utilization(TPS("End scheduler-tick"));
}
--
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