Re: IO-APIC problem with 2.6.14-rt9

[Ingo Molnar <mingo@elte.hu>]

* 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