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SubjectRe: IO-APIC problem with 2.6.14-rt9

* john stultz <johnstul@us.ibm.com> wrote:

> > > //#define ARCH_HAS_READ_CURRENT_TIMER 1
> > >
> > > to:
> > >
> > > #define ARCH_HAS_READ_CURRENT_TIMER 1
> > >
> > > ?
> >
> > It works !! Thanks Ingo for the immediate response
>
> Hrm. Could you post the value for BogoMIPS that you're getting now?
>
> My patches touch the __delay() code, since using the TSC based delay
> has just as many, if not more, problems as the loop based delay. So I
> want to be careful that my changes are not further causing problems.
>
> Ingo, did you commented out ARCH_HAS_READ_CURRENT_TIMER because of
> problems with the new calibration code?

yes. traces show that the new calibration code results in a bogomips
value on Athlon64 CPUs that halve the timeout. I.e. udelay(100) now
takes 50 usecs (!). The calibration code seems to assume the number of
cycles == number of loops in __delay() - that is not valid. The
calibration needs to happen based on some real clock, such as the PIT,
or PIT-driven jiffies.

Ingo
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