[ntp:questions] NTP + kernel frequency

Uwe Klein uwe_klein_habertwedt at t-online.de
Sun Nov 11 17:49:40 UTC 2007

David L. Mills wrote:

> 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.

The idea is to have a tickless system. This
is interesting not only for laptops but for (massively) virtualised
systems as well. ( Think of dozens of VMs going into galloping horde
mode to each service their (virtual) timer interrupt.

This does not mean that if requested a regular timer will not run.


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