Messages in this thread |  | | From | Roger Larsson <> | Subject | Re: Context switch times | Date | Sat, 6 Oct 2001 01:43:37 +0200 |
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On Saturday 06 October 2001 01:04, Alan Cox wrote: > > > This damps down task thrashing a bit, and for the cpu hogs it gets the > > > desired behaviour - which is that the all run their full quantum in the > > > background one after another instead of thrashing back and forth > > > > What if we give to prev a priority boost P=F(T) where T is the time > > prev is ran before the current schedule ? > > That would be the wrong key. You can argue certainly that it is maybe > appropriate to use some function based on remaining scheduler ticks, but > that already occurs as the scheduler ticks is the upper bound for priority > band
How about a LIFO list for each processor where preempted (count != 0) tasks go?
When a preemption occurs the current goes to the LIFO. When a process has run whole of its time slot - it can be moved to an usedup queue. (No point in keeping it on the generic run queue, but remember it when giving out new ticks, could also be on a per CPU basis). Now select what to do next.. The first on the LIFO can be moved in as "current" before checking the rest of the run queue...
Pros: + The LIFO will be sorted with highest prio on top - no need to search 'em all + a process that starts a time slot on one CPU stays the whole slot.
Cons: - A process might get stuck waiting for the processor in the FIFO while the other CPU is idle (but that was the point, wasn't it...)
/RogerL
-- Roger Larsson Skellefteå Sweden - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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