Re: [PATCH v4 1/4] Produce system time from correlated clocksource

Thomas Gleixner
2015-10-20T10:49:05Z

On Tue, 20 Oct 2015, Richard Cochran wrote:

> On Mon, Oct 19, 2015 at 05:36:56PM -0700, John Stultz wrote:
> > If we're only tracking 4ms of history, how does this solution
> > measurably improve the error over using the timestamps to generate
> > MONOTONIC_RAW clock deltas (which doesn't require keeping any history)
> > and using getnstime_raw_and_real to take an anchor point to calculate
> > the delta from? Why is adding complexity necessary?
>
> This idea is variant of what I suggested in another reply in this
> thread. To my understanding, there is no need at all to keep a
> history arbitrarily 4 ms long. Instead, the DSP driver (or whoever
> else may need such a thing) can simply sample the system time at the
> rate needed for that particular application.

That's complete nonsense. The whole point is to have a proper
correlation from ART/audio timestamps to system time. Sampling system
time does not help in any way,

Thanks,

tglx