linux内核的全局变量,Linux内核全局变量总结

1.current指针

各个平台、各个内核版本中current的实现可能不同；但原理是一样的。该指针一般定义在具体平台的current.h头文件中，类型为struct task_struct：

arch/arm/include/asm/current.h

#define current (get_current())

static inline struct task_struct *get_current(void)

include/linux/sched.h

struct task_struct {

......

struct thread_info *thread_info;

struct list_head tasks;

pid_t pid;

pid_t tgid;

uid_t uid,euid,suid,fsuid;

gid_t gid,egid,sgid,fsgid;

struct fs_struct *fs; //本节将大量使用这个

struct files_struct *files;

......

}2.jiffies系统开机后“滴答”数

include/linux/jiffies.h

extern u64 __jiffy_data jiffies_64;

extern unsigned long volatile __jiffy_data jiffies;

3.HZ、tick系统晶振主频，平台相关 arch/arm/include/asm/param.h

#ifdef __KERNEL__

# define HZ CONFIG_HZ /* Internal kernel timer frequency */

# define USER_HZ 100 /* User interfaces are in "ticks" */

# define CLOCKS_PER_SEC (USER_HZ) /* like times() */

#else

# define HZ 100

#endifinclude/linux/timex.h

extern unsigned long tick_usec; /* USER_HZ period (usec) */

extern unsigned long tick_nsec; /* ACTHZ period (nsec) */