Messages in this thread | | | Date | Thu, 07 Aug 2003 20:05:23 +1000 | From | Nick Piggin <> | Subject | Re: 2.6.0-test2-mm3 osdl-aim-7 regression |
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Con Kolivas wrote:
>On Thu, 7 Aug 2003 18:25, Nick Piggin wrote: > >>>The more frequently you round robin the lower the scheduler latency >>>between SCHED_OTHER tasks of the same priority. However, the longer the >>>timeslice the more benefit you get from cpu cache. Where is the sweet >>>spot? Depends on the hardware and your usage requirements of course, but >>>Ingo has empirically chosen 25ms after 50ms seemed too long. Basically >>>cache trashing becomes a real problem with timeslices below ~7ms on >>>modern hardware in my limited testing. A minor quirk in Ingo's original >>>code means _occasionally_ a task will be requeued with <3ms to go. It >>>will be interesting to see if fixing this (which O12.2+ does) makes a big >>>difference or whether we need to reconsider how frequently (if at all) we >>>round robin tasks. >>> >>Why not have it dynamic? CPU hogs get longer timeslices (but of course >>can be preempted by higher priorities). >> > >Funny you should say that. Before Ingo merged his A3 changes, that's what my >version of them did. > >
Between you and me, I think this would be the right way to go if it could be done right. I don't think wli, mjb and the rest of their clique appreciate the 25ms reschedule!
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