Messages in this thread | | | Date | Thu, 7 Aug 2003 13:45:59 -0700 | From | William Lee Irwin III <> | Subject | Re: Ingo Molnar and Con Kolivas 2.6 scheduler patches |
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On Wednesday 06 August 2003 22:28, Rob Landley wrote: >> So, how does SCHED_SOFTRR fail? Theoretically there is a minimum timeslice >> you can hand out, yes? And an upper bound on scheduling latency. So >> logically, there is some maximum number "N" of SCHED_SOFTRR tasks running >> at once where you wind up round-robining with minimal timeslices and the >> system is saturated. At N+1, you fall over. (And in reality, there are >> interrupts and kernel threads and other things going on that get kind of >> cramped somewhere below N.)
On Thu, Aug 07, 2003 at 04:42:55PM +0100, Daniel Phillips wrote: > The upper bound for softrr realtime scheduling isn't based on number > of tasks, it's a global slice of cpu time: so long as the sum of > running times of all softrr tasks in the system lies below limit, > softrr tasks will be scheduled as SCHED_RR, otherwise they will be > SCHED_NORMAL.
You're thinking of Little's law, which is describes the mean number of waiters on a queue as the mean service time divided by the number of servers times the mean inter-arrival time.
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