On 5/13/06, Ohad Ben-Cohen <ohadbc@xxxxxxxxx> wrote:
Hi, On 5/13/06, pradeep singh <2500.pradeep@xxxxxxxxx> wrote: > On 5/13/06, Ohad Ben-Cohen <ohadbc@xxxxxxxxx> wrote: > > > > the scheduler is an asynchronous kernel code. > > it is *not* a process. it is not always running. > > it is invoked (specifically, scheduler_tick() is) HZ times in a second > Can you give me a link of the source which shows on how it is invoked > so many time per sec? sure. this is very much architecture specific, so i'll show this in, for instance, the PowerPC architecture:
Thanks Ohad for the insight into scheduler working.Will look into the source.
start_kernel is called once at boot time. it calls time_init, which calibrates the needed delay according to the HZ and sets up the hardware decrementer clock (32-bit down counter that activates an interrupt at its terminal count). unlike x86, in PPC there is no installation of the timer interrupt, the handler call is hard coded at head.S. func src === === HZ definition http://lxr.linux.no/source/include/asm-ppc/param.h?a=ppc start_kernel http://lxr.linux.no/source/init/main.c?a=ppc#L416 time_init http://lxr.linux.no/source/arch/ppc/kernel/time.c?a=ppc#L286 registration http://lxr.linux.no/source/arch/ppc/kernel/head.S?a=ppc#L473 timer_interrupt http://lxr.linux.no/source/arch/ppc/kernel/time.c#L129 update_process_times http://lxr.linux.no/source/kernel/timer.c#L813 HTH, Ohad.
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