Messages in this thread | | | Date | Wed, 16 Jul 2014 09:12:52 +0200 (CEST) | From | Thomas Gleixner <> | Subject | Re: [patch 14/55] timekeeping: Provide internal ktime_t based data |
| |
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
| |