Re: gradual timeofday overhaul

From: Chris Friesen
Date: Mon Oct 25 2004 - 23:26:11 EST


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
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