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| author | Frederic Weisbecker <fweisbec@gmail.com> | 2013-07-11 19:12:32 +0200 |
|---|---|---|
| committer | Frederic Weisbecker <fweisbec@gmail.com> | 2013-08-14 17:12:46 +0200 |
| commit | 65f382fd0c8fa483713c0971de9f1dfb4cf1ad9c (patch) | |
| tree | dec89c43fcfb4934611bae4855293428382856b9 | |
| parent | d84d27a491880b9902b45c09be8d9e9464fb9b74 (diff) | |
| download | linux-65f382fd0c8fa483713c0971de9f1dfb4cf1ad9c.tar.gz linux-65f382fd0c8fa483713c0971de9f1dfb4cf1ad9c.tar.bz2 linux-65f382fd0c8fa483713c0971de9f1dfb4cf1ad9c.zip | |
context_tracking: Ground setup for static key use
Prepare for using a static key in the context tracking subsystem.
This will help optimizing the off case on its many users:
* user_enter, user_exit, exception_enter, exception_exit, guest_enter,
guest_exit, vtime_*()
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 | 10 | ||||
| -rw-r--r-- | init/main.c | 2 | ||||
| -rw-r--r-- | kernel/context_tracking.c | 23 |
3 files changed, 29 insertions, 6 deletions
diff --git a/include/linux/context_tracking.h b/include/linux/context_tracking.h index 1ae37c708c63..c138c24bad1a 100644 --- a/include/linux/context_tracking.h +++ b/include/linux/context_tracking.h @@ -4,6 +4,7 @@ #include <linux/sched.h> #include <linux/percpu.h> #include <linux/vtime.h> +#include <linux/static_key.h> #include <asm/ptrace.h> struct context_tracking { @@ -22,6 +23,7 @@ struct context_tracking { #ifdef CONFIG_CONTEXT_TRACKING +extern struct static_key context_tracking_enabled; DECLARE_PER_CPU(struct context_tracking, context_tracking); static inline bool context_tracking_in_user(void) @@ -67,6 +69,14 @@ static inline void context_tracking_task_switch(struct task_struct *prev, struct task_struct *next) { } #endif /* !CONFIG_CONTEXT_TRACKING */ + +#ifdef CONFIG_CONTEXT_TRACKING_FORCE +extern void context_tracking_init(void); +#else +static inline void context_tracking_init(void) { } +#endif /* CONFIG_CONTEXT_TRACKING_FORCE */ + + #ifdef CONFIG_VIRT_CPU_ACCOUNTING_GEN extern void guest_enter(void); extern void guest_exit(void); diff --git a/init/main.c b/init/main.c index d03d2ec2eacf..af310afbef28 100644 --- a/init/main.c +++ b/init/main.c @@ -75,6 +75,7 @@ #include <linux/blkdev.h> #include <linux/elevator.h> #include <linux/sched_clock.h> +#include <linux/context_tracking.h> #include <asm/io.h> #include <asm/bugs.h> @@ -545,6 +546,7 @@ asmlinkage void __init start_kernel(void) idr_init_cache(); rcu_init(); tick_nohz_init(); + context_tracking_init(); radix_tree_init(); /* init some links before init_ISA_irqs() */ early_irq_init(); diff --git a/kernel/context_tracking.c b/kernel/context_tracking.c index 72bcb2570d3e..839d377d0da5 100644 --- a/kernel/context_tracking.c +++ b/kernel/context_tracking.c @@ -20,15 +20,16 @@ #include <linux/hardirq.h> #include <linux/export.h> -DEFINE_PER_CPU(struct context_tracking, context_tracking) = { -#ifdef CONFIG_CONTEXT_TRACKING_FORCE - .active = true, -#endif -}; +struct static_key context_tracking_enabled = STATIC_KEY_INIT_FALSE; + +DEFINE_PER_CPU(struct context_tracking, context_tracking); void context_tracking_cpu_set(int cpu) { - per_cpu(context_tracking.active, cpu) = true; + if (!per_cpu(context_tracking.active, cpu)) { + per_cpu(context_tracking.active, cpu) = true; + static_key_slow_inc(&context_tracking_enabled); + } } /** @@ -202,3 +203,13 @@ void context_tracking_task_switch(struct task_struct *prev, clear_tsk_thread_flag(prev, TIF_NOHZ); set_tsk_thread_flag(next, TIF_NOHZ); } + +#ifdef CONFIG_CONTEXT_TRACKING_FORCE +void __init context_tracking_init(void) +{ + int cpu; + + for_each_possible_cpu(cpu) + context_tracking_cpu_set(cpu); +} +#endif |