Hi, On Wed, 20 Jul 2005, john stultz wrote:
> I really don't think the NTP changes I've mailed is very complex. > Please, be specific and point to something you think is an issue and > I'll do my best to fix it. Maybe I should explain, in what direction I would take it. Let's first only take tick based updates, one property I don't want to see go away (and which you remove in the last patch), is to basically update xtime at every tick by (tick_nsec+time_adj) (and maybe fold time_adjust into time_adj), no multiply/divide just adds/shifts. Every second (or maybe even less frequently) we update time_adj, where we even might integrate a better to way to add previous errors due to SHIFT_HZ. To add support for continous time sources, the generic ntp code would just provide [tick,frequency,offset] values and the time source converts it into its internal values. A tick based source calculates [tick_nsec, time_adj] and a continous source calculates the [offset,multiplier]. These values should be recalculated as infrequently as possible and not every single tick as you do with ppc_adjtimex. This also means a continous source updates xtime basically by calling gettimeofday (what ppc64 already almost does) and doesn't use update_wall_time() at all. Maybe I'm missing something, but I don't see a reason to forcibly merge both ways to update the clock, keep them seperate and let the generic ntp code provide the basic parameters which the time source uses to update the clock. The important thing is to precalculate as much as possible, so that the runtime overhead is as low as possible and these precalculations differ between time sources, so what your patches basically do is to remove all of these precalculations and I can't convince myself to see this as a good thing. BTW do you have any user space test code for this? This might be useful to verify that the changes are really correct and a prototype might be a good way to demonstrate the kernel changes. bye, Roman - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
