Re: [ANNOUNCE] ktimers subsystem

Thomas Gleixner
2005-09-19T22:58:23Z

On Mon, 2005-09-19 at 15:50 -0700, john stultz wrote:
> > 2. All gettimeofday implementations I have looked at do a lot of math
> > anyway, so its definitely more interesting to look at those oddities
> > rather than discussing a single add. John Stulz timeofday rework have a
> > clean solution for this - please do not argue about the div64 in his
> > original patches which he is reworking at the moment.
>
> The simplest solution is to keep wall-time maintained in a timespec as
> well as the nsec_t based system_time/wall_time_offset combo. This avoids
> the extra add in the hotpath, and only costs an extra add at interrupt
> time.

<NITPICKING>
The crucial question is what's the hot path ? Depending on the
application type I want to avoid the add in the interrupt code. :)
</NITPICKING>

> Many arches have userspace gtod implementations (x86-64, ppc64, and ia64
> as well). Although my timeofday code allows for this as well (I had it
> working for x86-64 awhile back).

Was not aware of that. Thanks for clarification.

tglx