On Wed, 8 Mar 2017, Alexandre Belloni wrote: > On 08/03/2017 at 13:33:33 +0000, Hadimani, Jagadish wrote: > > Hello Alexandre, > > > > I guess the Linux kernel uses HPET timer... > > But can we can force Linux kernel to use Tsc or per core timer... > > > > That is probably the case but your are targeting the wrong subsystem. > The timekeeping is done using two different devices: clocksource and > clockevent. Usually, the drivers are in drivers/clocksource. I'm > definitively not an expert in x86 but the clockevent seems to be > registered from arch/x86/kernel/hpet.c and the clocksource from > arch/x86/kernel/tsc.c > > IIRC the clocksource is optional but the clockevent is mandatory so if > you don't have an HPET, you will need to register a clockevent device > from somewhere else. > > Maybe the simplest thing to do is to ask the x86 maintainers and the > time maintainers. Luckily for you, they are the same people (Thomas and > Ingo, added in cc).
The scheduler uses TSC anyway. The RTC is only used for setting the wall clock time at boot and for figuring out the time a system spent in suspend. If you don't have an RTC then the boot wall clock time will be simply 1/1/1970 00:00:00. Jagadish, can you please explain what your problem is. Does the system fail to boot or does it behave strange or what? Thanks, tglx