This concludes the first part covering time and time management related concepts in the Linux kernel. We met first two concepts and its initialization in this part: `jiffies` and `clocksource`. In the next part we will continue to dive into this interesting theme and as I already wrote in this part we will acquainted and try to understand internals of these and other time management concepts in the Linux kernel.
This concludes the first part covering time and time management related concepts in the Linux kernel. We met first two concepts and its initialization in this part: `jiffies` and `clocksource`. In the next part we will continue to dive into this interesting theme and as I already wrote in this part we will acquainted and try to understand insides of these and other time management concepts in the Linux kernel.
If you have questions or suggestions, feel free to ping me in twitter [0xAX](https://twitter.com/0xAX), drop me [email](anotherworldofworld@gmail.com) or just create [issue](https://github.com/0xAX/linux-insides/issues/new).
@ -192,7 +192,7 @@ for the `x86` architectures. Where the `vDSO` clock mode can be one of the:
The last three fields are `wd_list`, `cs_last` and the `wd_last` depends on the `CONFIG_CLOCKSOURCE_WATCHDOG` kernel configuration option. First of all let's try to understand what is it `whatchdog`. In a simple words, watchdog is a timer that is used for detection of the computer malfunctions and recovering from it. All of these three fields contain watchdog related data that is used by the `clocksource` framework. If we will grep the Linux kernel source code, we will see that only [arch/x86/KConfig](https://github.com/torvalds/linux/blob/master/arch/x86/Kconfig#L54) kernel configuration file contains the `CONFIG_CLOCKSOURCE_WATCHDOG` kernel configuration option. So, why do `x86` and `x86_64` need in [watchdog](https://en.wikipedia.org/wiki/Watchdog_timer)? You already may know that all `x86` processors has special 64-bit register - [time stamp counter](https://en.wikipedia.org/wiki/Time_Stamp_Counter). This register contains number of [cycles](https://en.wikipedia.org/wiki/Clock_rate) since the reset. Sometimes the time stamp counter needs to be verified against another clock source. We will not see initialization of the `watchdog` timer in this part, before this we must learn more about timers.
That's all. From this moment we know all fields of the `clocksource` structure. This knowledge will help us to learn internals of the `clocksource` framework.
That's all. From this moment we know all fields of the `clocksource` structure. This knowledge will help us to learn insides of the `clocksource` framework.
@ -418,7 +418,7 @@ This is the end of the third part of the chapter that describes timers and timer
In the next part we will continue to dive into timer management related things in the Linux kernel and will see new concept for us - `timers`.
If you have questions or suggestions, feel free to ping me in twitter [0xAX](https://twitter.com/0xAX), drop me [email](anotherworldofworld@gmail.com) or just create [issue](https://github.com/0xAX/linux-internals/issues/new).
If you have questions or suggestions, feel free to ping me in twitter [0xAX](https://twitter.com/0xAX), drop me [email](anotherworldofworld@gmail.com) or just create [issue](https://github.com/0xAX/linux-insides/issues/new).
**Please note that English is not my first language and I am really sorry for any inconvenience. If you found any mistakes please send me PR to [linux-insides](https://github.com/0xAX/linux-insides).**
@ -408,7 +408,7 @@ This is the end of the fourth part of the chapter that describes timers and time
In the next part we will continue to dive into timer management related things in the Linux kernel and will see new concept for us - `timers`.
If you have questions or suggestions, feel free to ping me in twitter [0xAX](https://twitter.com/0xAX), drop me [email](anotherworldofworld@gmail.com) or just create [issue](https://github.com/0xAX/linux-internals/issues/new).
If you have questions or suggestions, feel free to ping me in twitter [0xAX](https://twitter.com/0xAX), drop me [email](anotherworldofworld@gmail.com) or just create [issue](https://github.com/0xAX/linux-insides/issues/new).
**Please note that English is not my first language and I am really sorry for any inconvenience. If you found any mistakes please send me PR to [linux-insides](https://github.com/0xAX/linux-insides).**
mudongliang
9 years ago