Re: gradual timeofday overhaul

[Chris Friesen]

George Anzinger wrote:

> Well, that is part of the accounting overhead the increases with context 
> switch rate.  You also need to include the time it takes to figure out 
> which of the time limits is closes (run time limit, profile time, slice 
> time, etc).  Then, you also need to remove the timer when switching 
> away.  No, it is not a lot, but it is way more than the nothing we do 
> when we can turn it all over to the periodic tick.  The choice is load 
> sensitive overhead vs flat overhead.

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.

Chris
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