Linux驱动开发九.内核定时器使用——定时器底层驱动 定时器和中断是我们最常用到的功能,在前面裸机开发的时候我们通过EPIT、GPT等定时器实现定时功能,那种算硬件定时器。今天我们来看下如何在Linux内核里实现软件定时功能的。 Linux内核时间管理 Linux系统在运行的时候有大量的函数需要时间管理,比如调度程序、延时程序等。
msecs_to_jiffies函数是 Linux 内核中的一个非常有用的函数,它用于将毫秒(milliseconds)转换为内核的“jiffies”单位。在 Linux 内核中,jiffies是一个全局变量,代表自系统启动以来经过的“滴答”(ticks)数,这里的“滴答”是系统时钟的一个固定周期,通常是几毫秒(如 10ms,但这取决于系统的HZ值,即每秒的时钟中断次...
函数名称:Convert jiffies to milliseconds and back.* Avoid unnecessary multiplications/divisions in the* two most common HZ cases: 返回类型:unsigned int 参数: 类型参数名称 const unsigned longj 377返回:Parameters used to convert the timespec values:除HZ乘j ...
Name:HZ is equal to or smaller than 1000, and 1000 is a nice round* multiple of HZ, divide with the factor between them, but round* upwards: Proto:static inline unsigned long _msecs_to_jiffies(const unsigned int m) Type:unsigned long Parameter: TypeParameterName const unsigned int m 311...
__builtin_constant_p() in msecs_to_jiffies(). The original msecs_to_jiffies is renamed to __msecs_to_jiffies and aside from the removal of the check for negative values being moved out, is unaltered. Signed-off-by: Nicholas Mc Guire <***@osadl.org> ...
函数名称:msecs_to_jiffies: - convert milliseconds to jiffies*@m: time in milliseconds* conversion is done as follows:* - negative values mean 'infinite timeout' (MAX_JIFFY_OFFSET)* - 'too large' values [that would result in larger than ...