Messages in this thread | | | Date | Thu, 06 Nov 2014 19:31:19 +0800 | From | Wanpeng Li <> | Subject | Re: [RFC PATCH v2] sched/deadline: support dl task migration during cpu hotplug |
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On 14/11/6 下午6:08, Peter Zijlstra wrote: > On Thu, Nov 06, 2014 at 09:46:34AM +0800, Wanpeng Li wrote: > >>> Ah, it could be that for offline cpus we have a singleton rd. Lemme try >> I still cannot find where build the singleton rd in the codes, could you >> point out? > So this is all quite horrible code, but what I think happens is that: > > sched_cpu_inactive() -> set_cpu_active(cpu, false); > cpuset_cpu_inactive() -> cpuset_update_active_cpus(false) > -> partition_sched_domains(1, NULL, NULL) > -> build_sched_domains(cpu_active_mask) > -> for_each_cpu() > cpu_attach_domain() -> rq_attach_root() > > Now, that will detach all active cpus from the current root domain and > attach them to the new root domain. Which leaves behind the old root > domain attached to only the one 'dead' cpu.
Got it, thanks for your great explanation. ;-)
Regards, Wanpeng Li
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