Messages in this thread | | | Date | Wed, 15 Feb 2006 11:58:56 +0100 (CET) | From | Roman Zippel <> | Subject | Re: time patches by Roman Zippel |
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Hi,
On Wed, 15 Feb 2006, Ulrich Windl wrote:
> > > Assuming 1024Hz interrupt frequency: > > > (1µs * 1000) / 1024 == 0ns; 0 * 1024 == 0µs, not 1µs > > > (2µs * 1000) / 1024 == 1ns; 1 * 1024 == 1.024µs, not 2µs > > > > Ok, I didn't put much effort into optimizing it for uncommon HZ values. > > Why is it so important? It's currently unused on any Linux machine > > synchronized via NTP. > > Roman, > > how do you know? When using "disable kernel", NTP relies on adjtime() to adjust > the time. Some people even prefer that, because the algorithms do floating point > math in user space instead of fixed-point maths in kernel space.
This still requires they choose an uncommon HZ value, which is not really likely. Anyway, it's not really difficult to add the remainder to time_adj_curr. Since the adjtime() has only a usec resolution and this rounding error is only 1 usec, I didn't consider it to be that important.
bye, Roman | |