Messages in this thread | | | Date | Tue, 11 May 2021 09:32:39 +0200 | From | Ingo Molnar <> | Subject | Re: [PATCH 1/2] sched: Make the idle task quack like a per-CPU kthread |
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* Valentin Schneider <valentin.schneider@arm.com> wrote:
> On 10/05/21 16:10, Valentin Schneider wrote: > > This requires some extra iffery as init_idle() > > call be called more than once on the same idle task. > > > > While I'm at it, do we actually still need to suffer through this?
No.
> AFAICT the extra calls are due to idle_thread_get() (used in cpuhp) > calling init_idle(). However it looks to me that since > > 3bb5d2ee396a ("smp, idle: Allocate idle thread for each possible cpu during boot") > > we don't need to do that: we already have a > > for_each_possible_cpu(cpu) > init_idle(cpu) > > issued at init. So can't we "simply" rely on that init-time creation, > given it's done against the possible mask? I think the only thing that > might need doing at later hotplug is making sure the preempt count is > right (secondary startups seem to all prepare the idle task by issuing a > preempt_disable()).
Best-case it works, worst-case we discover an unclean assumption in the init sequence and it works after we fix that.
Win-win. :-)
Thanks,
Ingo
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