Re: [PATCH 1/2] x86/tsc: Allow quick PIT calibration despite interruptions

2019-02-14 Thread Jan H . Schönherr
Am 12.02.19 um 12:57 schrieb Thomas Gleixner: On Tue, 29 Jan 2019, Thomas Gleixner wrote: On Tue, 29 Jan 2019, Jan H. Schönherr wrote: Am 29.01.2019 um 11:23 schrieb Jan H. Schönherr: +calibrate: + /* +* Extrapolate the error and fail fast if the error will +* never be b

Re: [PATCH 1/2] x86/tsc: Allow quick PIT calibration despite interruptions

2019-02-12 Thread Thomas Gleixner
On Tue, 29 Jan 2019, Thomas Gleixner wrote: > On Tue, 29 Jan 2019, Jan H. Schönherr wrote: > > > Am 29.01.2019 um 11:23 schrieb Jan H. Schönherr: > > > +calibrate: > > > + /* > > > + * Extrapolate the error and fail fast if the error will > > > + * never be below 500 ppm. > > > + */ > > > + if

Re: [PATCH 1/2] x86/tsc: Allow quick PIT calibration despite interruptions

2019-01-29 Thread Thomas Gleixner
On Tue, 29 Jan 2019, Jan H. Schönherr wrote: > Am 29.01.2019 um 11:23 schrieb Jan H. Schönherr: > > +calibrate: > > + /* > > +* Extrapolate the error and fail fast if the error will > > +* never be below 500 ppm. > > +*/ > > + if (d1 + d1 >= (delta * MAX_QUICK_PIT_ITERATIONS) >> 11

[PATCH 1/2] x86/tsc: Allow quick PIT calibration despite interruptions

2019-01-29 Thread Jan H . Schönherr
Some systems experience regular interruptions (60 Hz SMI?), that prevent the quick PIT calibration from succeeding: individual interruptions can be so long, that the PIT MSB is observed to decrement by 2 or 3 instead of 1. The existing code cannot recover from this. The system in question is an AM