Re: PSA: Clock drift and pkgin

On 2023-12-24 20:58, Jonathan Stone wrote:
> 
> 
> On Sunday, December 24, 2023 at 02:43:55 AM PST, Johnny Billquist 
> <[email protected]> wrote:
> 
>  > Oh? So we are actually not POSIX compliant on that one? Interesting.
>  > (POSIX explicitly says that the timeout should be for an absolute time,
>  > which means that if you for example update the clock, moving it
>  > backwards, the timeout should still only happen when that time arrives,
>  > and not after some precomputed number of ticks.)
> 
> one could keep track, for every timeout, whether it's relative or absolute;
> and when the time is changed, walk the list of a-yet-unfired timeouts,
> updating all the "absolute" timeouts by the clock-change delta.

One could, indeed. And then it would be compliant. (I'd dislike it, but 
that's a very personal opinion. :-) )

> Anyway .. I wonder if the "clock drift" is related to the clock drift 
> I've heard about,
> on machines which don't have a hardware cycle-counter-style clock, and 
> rely on clock-tick
> interrupts to track time. (for example, pmax 2100/3100; decstation 
> 5000/200; (most) vax).
> 
> I'd really like to help out with clock-drift', if I can do anything to 
> help.

I am fairly sure all systems use the clock tick interrupt to track time 
in the end. No NetBSD port, as far as I know, is running a tickless 
implementation.

But I think the suggestion that the time adjustment might actually be a 
source of the problem is interesting, and should be investigated. It 
just takes so bloody long to do a full build these days. I still haven't 
finished, and can't start chasing this quite yet.

   Johnny

-- 
Johnny Billquist                  || "I'm on a bus
                                   ||  on a psychedelic trip
email: [email protected]             ||  Reading murder books
pdp is alive!                     ||  tryin' to stay hip" - B. Idol