Messages in this thread | | | Date | Thu, 23 Jan 2014 12:32:52 +0000 | From | Morten Rasmussen <> | Subject | Re: [PATCH 2/2] sched: add statistic for rq->max_idle_balance_cost |
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On Thu, Jan 23, 2014 at 10:49:35AM +0000, Alex Shi wrote: > On 01/23/2014 05:54 PM, Peter Zijlstra wrote: > > On Thu, Jan 23, 2014 at 02:49:25PM +0800, Alex Shi wrote: > >> On 01/23/2014 02:10 AM, Jason Low wrote: > >>>>>>> P64(avg_idle); > >>>>>>> + P64(max_idle_balance_cost); > >>>>>>> #endif > >>>>>>> P(ttwu_count); > >>>>> > >>>>> Not also the per-sd value in sd_alloc_ctl_domain_table() ? > >>> Yeah, tracking the sd->max_newidle_lb_cost can also be useful. > >>> > >>> > >> > >> Thanks for suggestion! > >> > >> I thought the sd->max_newidle_lb_cost keep changing. But yes, it's > >> still meaningful. > >> BTW, in the pandaboard ES, sd balance cost is about 1~2ms. > > > > That's an insane amount of time for only 2 cpus. > > maybe, :( > > but it is the data. > $ cat /proc/sys/kernel/sched_domain/cpu0/domain0/max_newidle_lb_cost > 1873393
What sort of workload are you running? It seems rather extreme.
I did a quick test on TC2 and got max_newidle_lb_cost in the range ~7000-80000 when having a constantly running task on each cpu for a few seconds.
I also traced curr_cost just to get an idea of the cost of idle_balance. I get an average cost across all five cpus of around 7000.
Morten
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