Re: [PATCH] arm64, numa: Add cpu_to_node() implementation.

[Hanjun Guo]

On 09/20/2016 09:38 PM, Robert Richter wrote:
> On 20.09.16 19:32:34, Hanjun Guo wrote:
> > On 09/20/2016 06:43 PM, Robert Richter wrote:
>
> > > Instead we need to make sure the set_*numa_node() functions are called
> > > earlier before secondary cpus are booted. My suggested change for that
> > > is this:
> > >
> > >
> > > diff --git a/arch/arm64/kernel/smp.c b/arch/arm64/kernel/smp.c
> > > index d93d43352504..952365c2f100 100644
> > > --- a/arch/arm64/kernel/smp.c
> > > +++ b/arch/arm64/kernel/smp.c
> > > @@ -204,7 +204,6 @@ int __cpu_up(unsigned int cpu, struct task_struct *idle)
> > >   static void smp_store_cpu_info(unsigned int cpuid)
> > >   {
> > >   	store_cpu_topology(cpuid);
> > > -	numa_store_cpu_info(cpuid);
> > >   }
> > >
> > >   /*
> > > @@ -719,6 +718,7 @@ void __init smp_prepare_cpus(unsigned int max_cpus)
> > >   			continue;
> > >
> > >   		set_cpu_present(cpu, true);
> > > +		numa_store_cpu_info(cpu);
> > >   	}
> > >   }
> >
> > We tried a similar approach which add numa_store_cpu_info() in
> > early_map_cpu_to_node(), and remove it from smp_store_cpu_info,
> > but didn't work for us, we will try your approach to see if works.

And it works :)

> Calling it in early_map_cpu_to_node() is probably too early since
> setup_node_to_cpumask_map() is called in numa_init() afterwards
> overwriting it again.
>
> Actually, early_map_cpu_to_node() is used to temporarily store the
> mapping until it can be setup in numa_store_cpu_info().

Thanks for the clarify, let's wait for David's reply on this one.

Thanks
Hanjun