Re: CPU Hotplugging disabled, still cpuhp/%d threads running in my 32-bit system

[Enrico Mioso]

Thank you very much Thomas, really.
Enrico


Enrico Mioso
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On Wed, 11 Jan 2017, Thomas Gleixner wrote:

> Date: Wed, 11 Jan 2017 10:16:10
> From: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
> To: Enrico Mioso <mrkiko.rs@xxxxxxxxx>
> Cc: linux-kernel@xxxxxxxxxxxxxxx,
>     Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>,
>     Rasmus Villemoes <linux@xxxxxxxxxxxxxxxxxx>,
>     Peter Zijlstra <peterz@xxxxxxxxxxxxx>,
>     Anna-Maria Gleixner <anna-maria@xxxxxxxxxxxxx>,
>     Ingo Molnar <mingo@xxxxxxxxxx>,
>     Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx>
> Subject: Re: CPU Hotplugging disabled,
>     still cpuhp/%d threads running in my 32-bit system
>
> On Tue, 10 Jan 2017, Enrico Mioso wrote:
>
> > Hello guys.
> > I disabled CPU hotplugging in my .config: still I can see what follows in the
> > process list.
> >
> >    11 ?        S      0:00 [cpuhp/0]
> >    12 ?        S      0:00 [cpuhp/1]
> >
> > And from what I can see in kernel/cpu.c:574, this is related to CPU
> > hotplugging.
> > Is this normal? And, out of curiosity, why?
>
> Yes. We need the threads for bringing up the CPUs and for modules and other
> functionality to set up per cpu related things. The thread makes sure that
> the code runs on the CPUs and handles the functionality related to
> install/remove of hotplug callbacks.
>
> Thanks,
>
> 	tglx