Re: gradual timeofday overhaul
From: Chris Friesen
Date: Thu Oct 21 2004 - 22:14:49 EST
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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