Re: gradual timeofday overhaul

[Chris Friesen <cfriesen@nortelnetworks.com>]

George Anzinger wrote:
> Chris Friesen wrote:

>> It should be possible to be clever about this.  Most processes don't 
>> use their timeslice, so if we have a previous timer running, just keep 
>> track of how much beyond that timer our timeslice will be.  If we 
>> context switch before the timer expiry, well and good.  If the timer 
>> expires, set it for what's left of our timeslice.
> 
> 
> Me thinks that rather quickly devolves to a periodic tick.

In the busy case, yes.  But on an idle system you get tickless behaviour.

It's still going to be load-sensitive, since you are doing additional work to 
keep track of the timer/timeout values.  But it saves work if reprogramming the 
timer is time-consuming compared to simply reading it.  On something like the 
ppc, it probably doesn't buy you much since the decrementer is cheap to program.

Chris