Dear Haojian, On Tue, Apr 26, 2011 at 10:04 PM, Haojian Zhuang <haojian.zhuang@gmail.com> wrote:
On Tue, Apr 26, 2011 at 9:55 PM, Vikram Narayanan <vikram186@gmail.com> wrote:
Hi,
I want to enable the dynamic tick aka tickless kernel feature for the BSP which I am developing. What are all the architecture dependent changes that needs to be done for implementing it. There was one struct by the name dyn_tick_timer, which is located under linux/include/asm-arm/mach/time.h file. (which is removed from v 2.6.27) Now my question is that, are all the dyn_tick_timer functionalities are moved to a generic interface somewhere? CONFIG_NO_HZ is used instead.
I am aware of the CONFIG_NO_HZ option. I am asking about the implementation of it. To put in a more clear way. There was a structure in the kernel source linux/include/asm-arm/mach/time.h before 2.6.27 struct dyn_tick_timer { spinlock_t lock; unsigned int state; /* Current state */ int (*enable)(void); /* Enables dynamic tick */ int (*disable)(void); /* Disables dynamic tick */ void (*reprogram)(unsigned long); /* Reprograms the timer */ int (*handler)(int, void *); }; To enable dynamic tick timer, one should implement functions for enable, disable and reprogram. But this structure is no more used in the new kernel source. In 2007 linux symposium, 3 authors talked about implementing the tickless feature using HPET timers. Now my question where does the implementation lies in the ARM architecture. Vikram
Are the clock source and clockevent device timers enough to take care of the tickless feature? There's no relationship between NOHZ and clocksource/clockevent.
- Vikram
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