3f4724ea85
Allow to dynamically switch between tick and virtual based cputime accounting. This way we can provide a kind of "on-demand" virtual based cputime accounting. In this mode, the kernel relies on the context tracking subsystem to dynamically probe on kernel boundaries. This is in preparation for being able to stop the timer tick in more places than just the idle state. Doing so will depend on CONFIG_VIRT_CPU_ACCOUNTING_GEN which makes it possible to account the cputime without the tick by hooking on kernel/user boundaries. Depending whether the tick is stopped or not, we can switch between tick and vtime based accounting anytime in order to minimize the overhead associated to user hooks. Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Ingo Molnar <mingo@kernel.org> Cc: Li Zhong <zhong@linux.vnet.ibm.com> Cc: Namhyung Kim <namhyung.kim@lge.com> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Paul Gortmaker <paul.gortmaker@windriver.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Thomas Gleixner <tglx@linutronix.de>
73 lines
2.5 KiB
C
73 lines
2.5 KiB
C
#ifndef _LINUX_KERNEL_VTIME_H
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#define _LINUX_KERNEL_VTIME_H
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struct task_struct;
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#ifdef CONFIG_VIRT_CPU_ACCOUNTING
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extern void vtime_task_switch(struct task_struct *prev);
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extern void vtime_account_system(struct task_struct *tsk);
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extern void vtime_account_system_irqsafe(struct task_struct *tsk);
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extern void vtime_account_idle(struct task_struct *tsk);
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extern void vtime_account_user(struct task_struct *tsk);
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extern void vtime_account(struct task_struct *tsk);
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#ifdef CONFIG_VIRT_CPU_ACCOUNTING_GEN
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extern bool vtime_accounting_enabled(void);
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#else
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static inline bool vtime_accounting_enabled(void) { return true; }
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#endif
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#else /* !CONFIG_VIRT_CPU_ACCOUNTING */
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static inline void vtime_task_switch(struct task_struct *prev) { }
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static inline void vtime_account_system(struct task_struct *tsk) { }
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static inline void vtime_account_system_irqsafe(struct task_struct *tsk) { }
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static inline void vtime_account_user(struct task_struct *tsk) { }
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static inline void vtime_account(struct task_struct *tsk) { }
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static inline bool vtime_accounting_enabled(void) { return false; }
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#endif
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#ifdef CONFIG_VIRT_CPU_ACCOUNTING_GEN
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static inline void arch_vtime_task_switch(struct task_struct *tsk) { }
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static inline void vtime_user_enter(struct task_struct *tsk)
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{
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vtime_account_system(tsk);
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}
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static inline void vtime_user_exit(struct task_struct *tsk)
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{
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vtime_account_user(tsk);
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}
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#else
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static inline void vtime_user_enter(struct task_struct *tsk) { }
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static inline void vtime_user_exit(struct task_struct *tsk) { }
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#endif
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#ifdef CONFIG_IRQ_TIME_ACCOUNTING
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extern void irqtime_account_irq(struct task_struct *tsk);
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#else
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static inline void irqtime_account_irq(struct task_struct *tsk) { }
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#endif
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static inline void vtime_account_irq_enter(struct task_struct *tsk)
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{
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/*
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* Hardirq can interrupt idle task anytime. So we need vtime_account()
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* that performs the idle check in CONFIG_VIRT_CPU_ACCOUNTING.
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* Softirq can also interrupt idle task directly if it calls
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* local_bh_enable(). Such case probably don't exist but we never know.
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* Ksoftirqd is not concerned because idle time is flushed on context
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* switch. Softirqs in the end of hardirqs are also not a problem because
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* the idle time is flushed on hardirq time already.
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*/
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vtime_account(tsk);
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irqtime_account_irq(tsk);
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}
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static inline void vtime_account_irq_exit(struct task_struct *tsk)
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{
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/* On hard|softirq exit we always account to hard|softirq cputime */
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vtime_account_system(tsk);
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irqtime_account_irq(tsk);
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}
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#endif /* _LINUX_KERNEL_VTIME_H */
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