Re: Help with the high res timers

[john stultz <johnstul@us.ibm.com>]

On Wed, 2005-05-04 at 15:48 -0700, George Anzinger wrote:
> john stultz wrote:
> > Here is my possible solution: Still keeping Nish's soft-timer rework
> > where we use nanoseconds instead of ticks or jiffies, provide an
> > expected interrupt-period value, which gives you the maximum interval
> > length between ticks. Thus you schedule a regular-low-res timer for the
> > nanosecond value (exp_ns - expected_interrupt_period). When that timer
> > expires, you move the timer to the HR timer list and schedule an
> > interrupt for the remaining time.
> 
> Oh, I have been thinking along these same lines.  I don't recall at the moment, 
> but I depend on the timer retaining the absolute expire time as I set it.  This 
> is used both by the secondary timer, and by the rearm code.  I need to look more 
> closely at that.  

Glad we're on similar wavelengths. :)

> But this is picking things apart at a very low level and does 
> not, I think, address timer ordering to the point where I feel completely safe. 
>   I.e. will such a scheme allow a LR time at time X to expire after a HR timer 
> for time X+y.

Hmm. That sounds like an interesting problem as well, although I'm not
familiar enough with it to make a reasonable comment. Let me ponder it
for awhile and see what can be done.

thanks
-john



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