Re: [Xen-devel] [PATCH v4 04/11] x86/intel_pstate: avoid calling cpufreq_add_cpu() twice

["Wang, Wei W" <wei.w.wang@xxxxxxxxx>]

On 24/07/2015 21:36,  Jan Beulich wrote:
> >>> On 25.06.15 at 13:15, <wei.w.wang@xxxxxxxxx> wrote:
> > cpufreq_add_cpu() is already called in the hypercall code path (the
> > bottom of set_px_pminfo() and inside cpufreq_cpu_init()).
> > So, we remove the redundant calling here.
> 
> While I can see that currently the call is kind of pointless (as it can't do
> anything useful before Dom0 communicated the data obtained from ACPI),
> it's still logically correct to call the callback on the BP prior to 
> registering a hook
> for AP bringup. Otherwise you could (and perhaps should) as well defer the
> CPU notifier registration.
> 
> Otoh now that you're trying to introduce a driver independent of ACPI (and
> hence initialized at boot time) I wonder why you don't make use of what is
> here instead of deleting it.
> 

Ok, I will roll back to leave cpufreq_presmp_init() there.

Best,
Wei
> 
> > --- a/xen/drivers/cpufreq/cpufreq.c
> > +++ b/xen/drivers/cpufreq/cpufreq.c
> > @@ -632,8 +632,6 @@ static struct notifier_block cpu_nfb = {
> >
> >  static int __init cpufreq_presmp_init(void)  {
> > -    void *cpu = (void *)(long)smp_processor_id();
> > -    cpu_callback(&cpu_nfb, CPU_ONLINE, cpu);
> >      register_cpu_notifier(&cpu_nfb);
> >      return 0;
> >  }
> 


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