diff options
| author | Paul E. McKenney <paul.mckenney@linaro.org> | 2012-03-27 16:02:08 -0700 |
|---|---|---|
| committer | Paul E. McKenney <paulmck@linux.vnet.ibm.com> | 2012-05-02 14:43:23 -0700 |
| commit | 616c310e83b872024271c915c1b9ab505b9efad9 (patch) | |
| tree | 1339bc7b3bef920b4641a5af2f182e9dfa2a6632 /include/linux | |
| parent | 66f75a5d028beaf67c931435fdc3e7823125730c (diff) | |
rcu: Move PREEMPT_RCU preemption to switch_to() invocation
Currently, PREEMPT_RCU readers are enqueued upon entry to the scheduler.
This is inefficient because enqueuing is required only if there is a
context switch, and entry to the scheduler does not guarantee a context
switch.
The commit therefore moves the enqueuing to immediately precede the
call to switch_to() from the scheduler.
Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Tested-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'include/linux')
| -rw-r--r-- | include/linux/rcupdate.h | 1 | ||||
| -rw-r--r-- | include/linux/rcutiny.h | 6 | ||||
| -rw-r--r-- | include/linux/sched.h | 10 |
3 files changed, 11 insertions, 6 deletions
diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h index 20fb776a1d4a..bbfe7854a6a6 100644 --- a/include/linux/rcupdate.h +++ b/include/linux/rcupdate.h @@ -184,6 +184,7 @@ static inline int rcu_preempt_depth(void) /* Internal to kernel */ extern void rcu_sched_qs(int cpu); extern void rcu_bh_qs(int cpu); +extern void rcu_preempt_note_context_switch(void); extern void rcu_check_callbacks(int cpu, int user); struct notifier_block; extern void rcu_idle_enter(void); diff --git a/include/linux/rcutiny.h b/include/linux/rcutiny.h index e93df77176d1..080b5bdda28e 100644 --- a/include/linux/rcutiny.h +++ b/include/linux/rcutiny.h @@ -87,10 +87,6 @@ static inline void kfree_call_rcu(struct rcu_head *head, #ifdef CONFIG_TINY_RCU -static inline void rcu_preempt_note_context_switch(void) -{ -} - static inline void exit_rcu(void) { } @@ -102,7 +98,6 @@ static inline int rcu_needs_cpu(int cpu) #else /* #ifdef CONFIG_TINY_RCU */ -void rcu_preempt_note_context_switch(void); extern void exit_rcu(void); int rcu_preempt_needs_cpu(void); @@ -116,7 +111,6 @@ static inline int rcu_needs_cpu(int cpu) static inline void rcu_note_context_switch(int cpu) { rcu_sched_qs(cpu); - rcu_preempt_note_context_switch(); } /* diff --git a/include/linux/sched.h b/include/linux/sched.h index 81a173c0897d..8f3fd945070f 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -1905,12 +1905,22 @@ static inline void rcu_copy_process(struct task_struct *p) INIT_LIST_HEAD(&p->rcu_node_entry); } +static inline void rcu_switch_from(struct task_struct *prev) +{ + if (prev->rcu_read_lock_nesting != 0) + rcu_preempt_note_context_switch(); +} + #else static inline void rcu_copy_process(struct task_struct *p) { } +static inline void rcu_switch_from(struct task_struct *prev) +{ +} + #endif #ifdef CONFIG_SMP |