Messages in this thread | | | Date | Fri, 13 May 2005 11:53:30 +0530 | From | Srivatsa Vaddagiri <> | Subject | Re: [RFC] (How to) Let idle CPUs sleep |
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On Thu, May 12, 2005 at 08:08:26PM +0200, Martin Schwidefsky wrote: > I would prefer a solution where the busy CPU wakes up an idle CPU if the > imbalance is too large. Any scheme that requires an idle CPU to poll at > some intervals will have one of two problem: either the poll intervall > is large then the imbalance will stay around for a long time, or the > poll intervall is small then this will behave badly in a heavily > virtualized environment with many images.
I guess all the discussions we are having boils down to this: what is the max time one can afford to have an imbalanced system because of sleeping idle CPU not participating in load balance? 10ms, 100ms, 1 sec or more?
Maybe the answer depends on how much imbalance it is that we are talking of here. A high order of imbalance would mean that the sleeping idle CPUs have to be woken up quickly, while a low order imbalance could mean that we can let it sleep longer.
From all the discussions we have been having, I think a watchdog implementation makes more sense. Nick/Ingo, what do you think should be our final decision on this?
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Thanks and Regards, Srivatsa Vaddagiri, Linux Technology Center, IBM Software Labs, Bangalore, INDIA - 560017 - 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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