David L. Mills wrote: > Hal Murray wrote: > >> There is a lot of work going on in the Linux kernel to avoid >> unnecessary timer interrupts in order to save power on laptops >> and other systems running off batteries. > > Any work on the Linux kernel to avoid timer interrupts is incompatible > with NTP. This is not a bad or good judgement, just and engineering > constraint. If timer interrupts are disabled, disable NTP. > > On the issue about timer interrupts at frequencies other than 100 Hz, > this is easy to fix. The nanokernel code that left here uses a constant > SHIFT_PLL that must be scaled inversely as the timer interrupt > frequency. It does not need to be exact, but close. I don't know how or > even whether this code is mangled in the Linux kernel, but there you > have it. If provisions to fix this are not in the Linux kernel and the > timer frequency is other than 100 Hz, then the Linux build and install > process should not include ntpd; alternatively, the kernel discipline > must be disabled.
One can browse the Linux kernel NTP implementation here: http://lxr.linux.no/source/kernel/time/ntp.c The entire time directory might be of interest: http://lxr.linux.no/source/kernel/time/ The NTP_INTERVAL_FREQ macro is defined as: #ifdef CONFIG_NO_HZ #define NTP_INTERVAL_FREQ (2) #else #define NTP_INTERVAL_FREQ (HZ) #endif _______________________________________________ questions mailing list [email protected] https://lists.ntp.org/mailman/listinfo/questions
