text: #ifndef _LINUX_KERNEL_STAT_H
  #define _LINUX_KERNEL_STAT_H
  
  #include <linux/smp.h>
  #include <linux/threads.h>
  #include <linux/percpu.h>
  #include <linux/cpumask.h>
  #include <linux/interrupt.h>
  #include <linux/sched.h>
  #include <linux/vtime.h>
  #include <asm/irq.h>
  
  /*
   * 'kernel_stat.h' contains the definitions needed for doing
   * some kernel statistics (CPU usage, context switches ...),
   * used by rstatd/perfmeter
   */
  
  enum cpu_usage_stat {
  	CPUTIME_USER,
  	CPUTIME_NICE,
  	CPUTIME_SYSTEM,
  	CPUTIME_SOFTIRQ,
  	CPUTIME_IRQ,
  	CPUTIME_IDLE,
  	CPUTIME_IOWAIT,
  	CPUTIME_STEAL,
  	CPUTIME_GUEST,
  	CPUTIME_GUEST_NICE,
  	NR_STATS,
  };
  
  struct kernel_cpustat {
  	u64 cpustat[NR_STATS];
  };
  
  struct kernel_stat {
  	unsigned long irqs_sum;
  	unsigned int softirqs[NR_SOFTIRQS];
  };
  
  DECLARE_PER_CPU(struct kernel_stat, kstat);
  DECLARE_PER_CPU(struct kernel_cpustat, kernel_cpustat);
  
  /* Must have preemption disabled for this to be meaningful. */
  #define kstat_this_cpu this_cpu_ptr(&kstat)
  #define kcpustat_this_cpu this_cpu_ptr(&kernel_cpustat)
  #define kstat_cpu(cpu) per_cpu(kstat, cpu)
  #define kcpustat_cpu(cpu) per_cpu(kernel_cpustat, cpu)
  
  extern unsigned long long nr_context_switches(void);
  
  extern unsigned int kstat_irqs_cpu(unsigned int irq, int cpu);
  extern void kstat_incr_irq_this_cpu(unsigned int irq);
  
  static inline void kstat_incr_softirqs_this_cpu(unsigned int irq)
  {
  	__this_cpu_inc(kstat.softirqs[irq]);
  }
  
  static inline unsigned int kstat_softirqs_cpu(unsigned int irq, int cpu)
  {
         return kstat_cpu(cpu).softirqs[irq];
  }
  
  /*
   * Number of interrupts per specific IRQ source, since bootup
   */
  extern unsigned int kstat_irqs(unsigned int irq);
  extern unsigned int kstat_irqs_usr(unsigned int irq);
  
  /*
   * Number of interrupts per cpu, since bootup
   */
  static inline unsigned int kstat_cpu_irqs_sum(unsigned int cpu)
  {
  	return kstat_cpu(cpu).irqs_sum;
  }
  
  extern void account_user_time(struct task_struct *, u64);
  extern void account_guest_time(struct task_struct *, u64);
  extern void account_system_time(struct task_struct *, int, u64);
  extern void account_system_index_time(struct task_struct *, u64,
  				      enum cpu_usage_stat);
  extern void account_steal_time(u64);
  extern void account_idle_time(u64);
  
  #ifdef CONFIG_VIRT_CPU_ACCOUNTING_NATIVE
  static inline void account_process_tick(struct task_struct *tsk, int user)
  {
  	vtime_flush(tsk);
  }
  #else
  extern void account_process_tick(struct task_struct *, int user);
  #endif
  
  extern void account_idle_ticks(unsigned long ticks);
  
  #endif /* _LINUX_KERNEL_STAT_H */
  