Messages in this thread | | | Date | Wed, 20 Apr 2011 16:10:18 +0100 | From | Ed W <> | Subject | Re: Improved TSC calculation |
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On 14/04/2011 19:20, john stultz wrote: > On Thu, 2011-04-14 at 12:19 +0100, Ed W wrote:
>> Before I try and hack probably an (inadequate) solution myself, do you >> have any thoughts on the best solution to extend your commit to non >> PM/HEPT machine? My initial thought was to repeatedly call >> pit_calibrate_tsc() with an extended latch, looking for a stable >> solution (ie refactor native_calibrate_tsc() ). Is this workable? >> Better ideas? > > Oof. So with the PIT you can maybe utilize the second channel/counter, > using a largish long countdown to try to get a similar functionality. > The only big concern is that the timer interrupt hardware is always > problematic (every time we chanage our usage, some random chunk of > laptops seem to stop working). So whatever solution that works for you > might not be able to be generically deployed. But I think it could be > interesting and might be worth you giving it a shot. > > I'd probably look at reworking tsc_refine_calibration_work, extending > the tsc_read_refs() code to also get PIT count values and then start the > long PIT countdown on the second channel before we > schedule_delayed_work.
OK, I have digested that and come to the conclusion that this might be a little beyond what I can easily code up... Any chance of some hints to get started from those that know what they are doing here?
Cheers
Ed W
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