Messages in this thread | | | Date | Thu, 18 Jul 2013 11:32:18 +0200 | From | Peter Zijlstra <> | Subject | Re: [RFC] sched: Limit idle_balance() when it is being used too frequently |
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On Wed, Jul 17, 2013 at 09:02:24PM -0700, Jason Low wrote:
> I ran a few AIM7 workloads for the 8 socket HT enabled case and I needed > to set N to more than 20 in order to get the big performance gains. > > One thing that I thought of was to have N be based on how often idle > balance attempts does not pull task(s). > > For example, N can be calculated based on the number of idle balance > attempts for the CPU since the last "successful" idle balance attempt. > So if the previous 30 idle balance attempts resulted in no tasks moved, > then n = 30 / 5. So idle balance gets less time to run as the number of > unneeded idle balance attempts increases, and thus N will not be set too > high during situations where idle balancing is "successful" more often. > Any comments on this idea?
It would be good to get a solid explanation for why we need such high N. But yes that might work.
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