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| author | Frederic Weisbecker <fweisbec@gmail.com> | 2013-07-11 19:42:13 +0200 |
|---|---|---|
| committer | Frederic Weisbecker <fweisbec@gmail.com> | 2013-08-14 17:14:47 +0200 |
| commit | 73d424f9af7b571276e6284617cb59726d47bf12 (patch) | |
| tree | 6ee47dd0327e67c8514ebfefc12728b030e79ae5 | |
| parent | 48d6a816a8bf36e2a197c322697323003bdc1cfe (diff) | |
| download | linux-73d424f9af7b571276e6284617cb59726d47bf12.tar.gz linux-73d424f9af7b571276e6284617cb59726d47bf12.tar.bz2 linux-73d424f9af7b571276e6284617cb59726d47bf12.zip | |
context_tracking: Optimize context switch off case with static keys
No need for syscall slowpath if no CPU is full dynticks,
rather nop this in this case.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Li Zhong <zhong@linux.vnet.ibm.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Kevin Hilman <khilman@linaro.org>
| -rw-r--r-- | include/linux/context_tracking.h | 11 | ||||
| -rw-r--r-- | kernel/context_tracking.c | 6 |
2 files changed, 12 insertions, 5 deletions
diff --git a/include/linux/context_tracking.h b/include/linux/context_tracking.h index 8854eadb2142..e070ea5dadac 100644 --- a/include/linux/context_tracking.h +++ b/include/linux/context_tracking.h @@ -40,6 +40,8 @@ extern void context_tracking_cpu_set(int cpu); extern void context_tracking_user_enter(void); extern void context_tracking_user_exit(void); +extern void __context_tracking_task_switch(struct task_struct *prev, + struct task_struct *next); static inline void user_enter(void) { @@ -74,8 +76,12 @@ static inline void exception_exit(enum ctx_state prev_ctx) } } -extern void context_tracking_task_switch(struct task_struct *prev, - struct task_struct *next); +static inline void context_tracking_task_switch(struct task_struct *prev, + struct task_struct *next) +{ + if (static_key_false(&context_tracking_enabled)) + __context_tracking_task_switch(prev, next); +} #else static inline bool context_tracking_in_user(void) { return false; } static inline void user_enter(void) { } @@ -112,6 +118,7 @@ static inline void guest_exit(void) else current->flags &= ~PF_VCPU; } + #else static inline void guest_enter(void) { diff --git a/kernel/context_tracking.c b/kernel/context_tracking.c index b6a186c4b886..c17822673c39 100644 --- a/kernel/context_tracking.c +++ b/kernel/context_tracking.c @@ -166,7 +166,7 @@ void context_tracking_user_exit(void) } /** - * context_tracking_task_switch - context switch the syscall callbacks + * __context_tracking_task_switch - context switch the syscall callbacks * @prev: the task that is being switched out * @next: the task that is being switched in * @@ -178,8 +178,8 @@ void context_tracking_user_exit(void) * migrate to some CPU that doesn't do the context tracking. As such the TIF * flag may not be desired there. */ -void context_tracking_task_switch(struct task_struct *prev, - struct task_struct *next) +void __context_tracking_task_switch(struct task_struct *prev, + struct task_struct *next) { clear_tsk_thread_flag(prev, TIF_NOHZ); set_tsk_thread_flag(next, TIF_NOHZ); |