Re: /proc or ps tools bug? 2.6.3, time is off

[Tim Schmielau]

On Tue, 4 May 2004, john stultz wrote:

> On Mon, 2004-05-03 at 23:12, Tim Schmielau wrote:
> > 
> > I wonder whether it's conceptually correct to use jiffies for accurate 
> > long-time measurements at all. ntpd is there for a reason. Using both
> > corrected, accurate and freely running clocks IMHO is calling for trouble. 
> > This might be something to think about for 2.7.
> 
> Indeed. Moving away from jiffies as a time counter and more of an
> interrupt counter is important. That allows for implementations of
> variable HZ and other things the high-res timer folks want without
> affecting the time keeping code. 
> 
> Roughly, I'd like to see the time code for all arches in 2.7 to look
> like:

[simple, well thought-out proposal snipped]

> time_interrupt_hook(): 
>         updates system_time.


> Of course, with this approach, we actually have to be able to trust the
> hardware 100%. With the current state of i386 hw having serious problems
> w/ reliable timesources, this may be difficult. 

Well, with some configurable plausibility checks in time_interrupt_hook()
it shouldn't be worse than what we have now...

> I've got a bigger proposal (with proper credits to Keith Mannthey and
> George Anzinger for reviews and corrections) that I wrote up awhile
> back, and I'll likely send it out if this sketch gathers any interest.  

Yes, that sounds interesting. It's just that I won't have any spare time 
to spend in the next two weeks.

Tim
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