On Wed, 16 Jul 2014, Thomas Gleixner wrote:
> On Tue, 15 Jul 2014, John Stultz wrote:
> > Hrmm.. So I do understand why this is useful performance wise.
> > However, I'm really starting to feel that keeping all this duplicate
> > data is a real maintenance burden, as remembering to keep the values
> > in sync always is prone to error.
> >
> > So I may have to just put up with it, but I'd like to start thinking
> > about how to reduce the duplicated data in the future. Arnd had an
> > interesting idea for something like storing fixed point seconds, which
> > could be cheaply converted to either ktime_t or timespec values.
> > However, I suspect that would be even more complex for folks to
> > understand, which I'd rather not do.
> >
> > Overall, it might be best if we just kill the timespec
> > wall_to_monotonic/total_sleep_time/tai_offset values and keep the
> > timekeeper values almost all in timespecs. Then we can leave the
>
> So we kill the time specs and store everything in timespecs :)
>
> > conversion process to basically cache the timespec values to the
> > vsyscall_update logic?
Looking into it I think for now it's the least risky approach to keep
the core logic based on the timespec stuff unmodified and update the
ktime_t members in timekeeping_update(). Converting the whole thing to
a pure nsec based mechanism and update the timespec stuff in
timekeeping_update() needs a lot more thought and we should do that
later on. It wont change any of the interfaces.
Thanks,
tglx
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majord...@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
