Messages in this thread Patch in this message | | | From | Frederic Weisbecker <> | Subject | [PATCH 09/23] context_tracking: Optimize guest APIs off case with static key | Date | Thu, 1 Aug 2013 02:31:26 +0200 |
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Optimize guest entry/exit APIs with static keys. This minimize the overhead for those who enable CONFIG_NO_HZ_FULL without always using it. Having no range passed to nohz_full= should result in the probes overhead to be minimized.
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> --- include/linux/context_tracking.h | 19 +++++++++++++++++-- kernel/context_tracking.c | 23 ++--------------------- kernel/sched/cputime.c | 2 ++ 3 files changed, 21 insertions(+), 23 deletions(-)
diff --git a/include/linux/context_tracking.h b/include/linux/context_tracking.h index e5ec0c9..03a32b0 100644 --- a/include/linux/context_tracking.h +++ b/include/linux/context_tracking.h @@ -87,8 +87,23 @@ static inline void context_tracking_task_switch(struct task_struct *prev, #endif /* !CONFIG_CONTEXT_TRACKING */ #ifdef CONFIG_VIRT_CPU_ACCOUNTING_GEN -extern void guest_enter(void); -extern void guest_exit(void); +static inline void guest_enter(void) +{ + if (static_key_false(&context_tracking_enabled) && + vtime_accounting_enabled()) + vtime_guest_enter(current); + else + current->flags |= PF_VCPU; +} + +static inline void guest_exit(void) +{ + if (static_key_false(&context_tracking_enabled) && + vtime_accounting_enabled()) + vtime_guest_exit(current); + 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 657f668..5afa36b 100644 --- a/kernel/context_tracking.c +++ b/kernel/context_tracking.c @@ -21,8 +21,10 @@ #include <linux/export.h> struct static_key context_tracking_enabled = STATIC_KEY_INIT_FALSE; +EXPORT_SYMBOL_GPL(context_tracking_enabled); DEFINE_PER_CPU(struct context_tracking, context_tracking); +EXPORT_SYMBOL_GPL(context_tracking); void context_tracking_cpu_set(int cpu) { @@ -163,27 +165,6 @@ void context_tracking_user_exit(void) local_irq_restore(flags); } -#ifdef CONFIG_VIRT_CPU_ACCOUNTING_GEN -void guest_enter(void) -{ - if (vtime_accounting_enabled()) - vtime_guest_enter(current); - else - current->flags |= PF_VCPU; -} -EXPORT_SYMBOL_GPL(guest_enter); - -void guest_exit(void) -{ - if (vtime_accounting_enabled()) - vtime_guest_exit(current); - else - current->flags &= ~PF_VCPU; -} -EXPORT_SYMBOL_GPL(guest_exit); -#endif /* CONFIG_VIRT_CPU_ACCOUNTING_GEN */ - - /** * context_tracking_task_switch - context switch the syscall callbacks * @prev: the task that is being switched out diff --git a/kernel/sched/cputime.c b/kernel/sched/cputime.c index 223a35e..bb6b29a 100644 --- a/kernel/sched/cputime.c +++ b/kernel/sched/cputime.c @@ -724,6 +724,7 @@ void vtime_guest_enter(struct task_struct *tsk) current->flags |= PF_VCPU; write_sequnlock(&tsk->vtime_seqlock); } +EXPORT_SYMBOL_GPL(vtime_guest_enter); void vtime_guest_exit(struct task_struct *tsk) { @@ -732,6 +733,7 @@ void vtime_guest_exit(struct task_struct *tsk) current->flags &= ~PF_VCPU; write_sequnlock(&tsk->vtime_seqlock); } +EXPORT_SYMBOL_GPL(vtime_guest_exit); void vtime_account_idle(struct task_struct *tsk) { -- 1.7.5.4
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