| Date | Wed, 16 Jul 2014 09:00:38 +0200 (CEST) | From | Thomas Gleixner <> | Subject | Re: [patch 14/55] timekeeping: Provide internal ktime_t based data |
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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?
> Or if we do want to maintain performance for non-vdso implementations, > maybe we can split the timespec functions out of the timekeeping core > and do a similar single shot update each tick to set the update the > tiemspec cached values. But that can be layered over the timekeeping > core and we can avoid the crazy updating 2 values any time we change > one logic we currently have.
Makes sense. Lemme have a stab on it.
Thanks,
tglx
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