Commit-ID: 65f382fd0c8fa483713c0971de9f1dfb4cf1ad9c
Gitweb: http://git.kernel.org/tip/65f382fd0c8fa483713c0971de9f1dfb4cf1ad9c
Author: Frederic Weisbecker <fweisbec@xxxxxxxxx>
AuthorDate: Thu, 11 Jul 2013 19:12:32 +0200
Committer: Frederic Weisbecker <fweisbec@xxxxxxxxx>
CommitDate: Wed, 14 Aug 2013 17:12:46 +0200
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@xxxxxxxxx>
Cc: Steven Rostedt <rostedt@xxxxxxxxxxx>
Cc: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Borislav Petkov <bp@xxxxxxxxx>
Cc: Li Zhong <zhong@xxxxxxxxxxxxxxxxxx>
Cc: Mike Galbraith <efault@xxxxxx>
Cc: Kevin Hilman <khilman@xxxxxxxxxx>
---
include/linux/context_tracking.h | 10 ++++++++++
init/main.c | 2 ++
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 1ae37c7..c138c24 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 d03d2ec..af310af 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 72bcb25..839d377 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
--
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