From 73d424f9af7b571276e6284617cb59726d47bf12 Mon Sep 17 00:00:00 2001 From: Frederic Weisbecker Date: Thu, 11 Jul 2013 19:42:13 +0200 Subject: 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 Cc: Steven Rostedt Cc: Paul E. McKenney Cc: Ingo Molnar Cc: Thomas Gleixner Cc: Peter Zijlstra Cc: Borislav Petkov Cc: Li Zhong Cc: Mike Galbraith Cc: Kevin Hilman --- include/linux/context_tracking.h | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-) (limited to 'include') 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) { -- cgit v1.2.3