Ah...thank you....u just taught me several key API .....thanks. But now I am yearning for more....:=). On Sat, Sep 20, 2008 at 12:03 AM, Sitsofe Wheeler <sitsofe@xxxxxxxxx> wrote: > Peter Teoh wrote: >> >> On 9/18/08, Sitsofe Wheeler <sitsofe@xxxxxxxxx> wrote: >>> >>> Just after start up the kernel decides which hardware clock source it >>> deems >>> to be the best after tests (the order on x86 from most to least prefered >>> is >>> roughly HPET, ACPI, TSC, PIT) and goes on to only use that (after >> >> I am curious to know - where is this in the source code? > > select_clocksource in kernel/time/clocksource.c iterates through available > clock sources - > http://lxr.linux.no/linux+v2.6.26.5/kernel/time/clocksource.c#L265 . Clock > sources register themselves using clocksource_register and are scattered > across several files. > Q1: the assembly instruction: "rdtsc" will always get its clocking from PIT right? Q2: the remark for select_clocksource() said it will select the best, but the function is a loopless, deterministic function that just return value from a linked list. Hm.....cannot understand it usage... -- Regards, Peter Teoh -- To unsubscribe from this list: send an email with "unsubscribe kernelnewbies" to ecartis@xxxxxxxxxxxx Please read the FAQ at http://kernelnewbies.org/FAQ
