vtime: Optimize full dynticks accounting off case with static keys

If no CPU is in the full dynticks range, we can avoid the full
dynticks cputime accounting through generic vtime along with its
overhead and use the traditional tick based accounting instead.

Let's do this and nope the off case with static keys.

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>

1 files changed, 4 insertions, 18 deletions

diff --git a/kernel/sched/cputime.c b/kernel/sched/cputime.c
index b62d5c027c7e..0831b06aab97 100644
--- a/kernel/sched/cputime.c
+++ b/kernel/sched/cputime.c
@@ -378,11 +378,8 @@ static inline void irqtime_account_process_tick(struct task_struct *p, int user_
 #ifdef CONFIG_VIRT_CPU_ACCOUNTING
 
 #ifndef __ARCH_HAS_VTIME_TASK_SWITCH
-void vtime_task_switch(struct task_struct *prev)
+void vtime_common_task_switch(struct task_struct *prev)
 {
-        if (!vtime_accounting_enabled())
-                return;
-
         if (is_idle_task(prev))
                 vtime_account_idle(prev);
         else
@@ -404,11 +401,8 @@ void vtime_task_switch(struct task_struct *prev)
  * vtime_account().
  */
 #ifndef __ARCH_HAS_VTIME_ACCOUNT
-void vtime_account_irq_enter(struct task_struct *tsk)
+void vtime_common_account_irq_enter(struct task_struct *tsk)
 {
-        if (!vtime_accounting_enabled())
-                return;
-
         if (!in_interrupt()) {
                 /*
                  * If we interrupted user, context_tracking_in_user()
@@ -428,7 +422,7 @@ void vtime_account_irq_enter(struct task_struct *tsk)
         }
         vtime_account_system(tsk);
 }
-EXPORT_SYMBOL_GPL(vtime_account_irq_enter);
+EXPORT_SYMBOL_GPL(vtime_common_account_irq_enter);
 #endif /* __ARCH_HAS_VTIME_ACCOUNT */
 #endif /* CONFIG_VIRT_CPU_ACCOUNTING */
 
@@ -669,11 +663,8 @@ void vtime_account_system(struct task_struct *tsk)
         write_sequnlock(&tsk->vtime_seqlock);
 }
 
-void vtime_account_irq_exit(struct task_struct *tsk)
+void vtime_gen_account_irq_exit(struct task_struct *tsk)
 {
-        if (!vtime_accounting_enabled())
-                return;
-
         write_seqlock(&tsk->vtime_seqlock);
         if (context_tracking_in_user())
                 tsk->vtime_snap_whence = VTIME_USER;
@@ -732,11 +723,6 @@ void vtime_account_idle(struct task_struct *tsk)
         account_idle_time(delta_cpu);
 }
 
-bool vtime_accounting_enabled(void)
-{
-        return context_tracking_active();
-}
-
 void arch_vtime_task_switch(struct task_struct *prev)
 {
         write_seqlock(&prev->vtime_seqlock);