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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>
This commit is contained in:
Frederic Weisbecker 2013-07-12 03:10:15 +02:00
parent a5725ac23b
commit b049340613
3 changed files with 67 additions and 31 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

6
include/linux/context_tracking.h
View File

@ -74,8 +74,7 @@ static inline void context_tracking_init(void) { }
#ifdef CONFIG_VIRT_CPU_ACCOUNTING_GEN
static inline void guest_enter(void)
{
if (static_key_false(&context_tracking_enabled) &&
vtime_accounting_enabled())
if (vtime_accounting_enabled())
vtime_guest_enter(current);
else
current->flags |= PF_VCPU;
@ -83,8 +82,7 @@ static inline void guest_enter(void)
static inline void guest_exit(void)
{
if (static_key_false(&context_tracking_enabled) &&
vtime_accounting_enabled())
if (vtime_accounting_enabled())
vtime_guest_exit(current);
else
current->flags &= ~PF_VCPU;

70
include/linux/vtime.h
View File

@ -1,22 +1,68 @@
#ifndef _LINUX_KERNEL_VTIME_H
#define _LINUX_KERNEL_VTIME_H
#include <linux/context_tracking_state.h>
#ifdef CONFIG_VIRT_CPU_ACCOUNTING_NATIVE
#include <asm/vtime.h>
#endif
struct task_struct;
/*
* vtime_accounting_enabled() definitions/declarations
*/
#ifdef CONFIG_VIRT_CPU_ACCOUNTING_NATIVE
static inline bool vtime_accounting_enabled(void) { return true; }
#endif /* CONFIG_VIRT_CPU_ACCOUNTING_NATIVE */
#ifdef CONFIG_VIRT_CPU_ACCOUNTING_GEN
static inline bool vtime_accounting_enabled(void)
{
if (static_key_false(&context_tracking_enabled)) {
if (context_tracking_active())
return true;
}
return false;
}
#endif /* CONFIG_VIRT_CPU_ACCOUNTING_GEN */
#ifndef CONFIG_VIRT_CPU_ACCOUNTING
static inline bool vtime_accounting_enabled(void) { return false; }
#endif /* !CONFIG_VIRT_CPU_ACCOUNTING */
/*
* Common vtime APIs
*/
#ifdef CONFIG_VIRT_CPU_ACCOUNTING
#ifdef __ARCH_HAS_VTIME_TASK_SWITCH
extern void vtime_task_switch(struct task_struct *prev);
#else
extern void vtime_common_task_switch(struct task_struct *prev);
static inline void vtime_task_switch(struct task_struct *prev)
{
if (vtime_accounting_enabled())
vtime_common_task_switch(prev);
}
#endif /* __ARCH_HAS_VTIME_TASK_SWITCH */
extern void vtime_account_system(struct task_struct *tsk);
extern void vtime_account_idle(struct task_struct *tsk);
extern void vtime_account_user(struct task_struct *tsk);
extern void vtime_account_irq_enter(struct task_struct *tsk);
#ifdef CONFIG_VIRT_CPU_ACCOUNTING_NATIVE
static inline bool vtime_accounting_enabled(void) { return true; }
#endif
#ifdef __ARCH_HAS_VTIME_ACCOUNT
extern void vtime_account_irq_enter(struct task_struct *tsk);
#else
extern void vtime_common_account_irq_enter(struct task_struct *tsk);
static inline void vtime_account_irq_enter(struct task_struct *tsk)
{
if (vtime_accounting_enabled())
vtime_common_account_irq_enter(tsk);
}
#endif /* __ARCH_HAS_VTIME_ACCOUNT */
#else /* !CONFIG_VIRT_CPU_ACCOUNTING */
@ -24,14 +70,20 @@ static inline void vtime_task_switch(struct task_struct *prev) { }
static inline void vtime_account_system(struct task_struct *tsk) { }
static inline void vtime_account_user(struct task_struct *tsk) { }
static inline void vtime_account_irq_enter(struct task_struct *tsk) { }
static inline bool vtime_accounting_enabled(void) { return false; }
#endif
#endif /* !CONFIG_VIRT_CPU_ACCOUNTING */
#ifdef CONFIG_VIRT_CPU_ACCOUNTING_GEN
extern void arch_vtime_task_switch(struct task_struct *tsk);
extern void vtime_account_irq_exit(struct task_struct *tsk);
extern bool vtime_accounting_enabled(void);
extern void vtime_gen_account_irq_exit(struct task_struct *tsk);
static inline void vtime_account_irq_exit(struct task_struct *tsk)
{
if (vtime_accounting_enabled())
vtime_gen_account_irq_exit(tsk);
}
extern void vtime_user_enter(struct task_struct *tsk);
static inline void vtime_user_exit(struct task_struct *tsk)
{
vtime_account_user(tsk);
@ -39,7 +91,7 @@ static inline void vtime_user_exit(struct task_struct *tsk)
extern void vtime_guest_enter(struct task_struct *tsk);
extern void vtime_guest_exit(struct task_struct *tsk);
extern void vtime_init_idle(struct task_struct *tsk, int cpu);
#else
#else /* !CONFIG_VIRT_CPU_ACCOUNTING_GEN */
static inline void vtime_account_irq_exit(struct task_struct *tsk)
{
/* On hard|softirq exit we always account to hard|softirq cputime */

22
kernel/sched/cputime.c
View File

@ -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);