Subject: Re: [PATCH v2 5/6] powerpc/smp: Add read_mostly attribute

From: Michael Ellerman <[email-masked]>
Date: Thu, 19 Oct 2023 15:49:48 +1100

Srikar Dronamraju <[email-masked]> writes:
> There are some variables that are only updated at boot time.
> So add read_mostly attribute to such variables

If they're only updated at boot time then __ro_after_init would be the
better annotation.

cheers

> diff --git a/arch/powerpc/kernel/smp.c b/arch/powerpc/kernel/smp.c
> index 29da9262cb17..b1eb11a66902 100644
> --- a/arch/powerpc/kernel/smp.c
> +++ b/arch/powerpc/kernel/smp.c
> @@ -77,10 +77,10 @@ static DEFINE_PER_CPU(int, cpu_state) = { 0 };
>  #endif
>  
>  struct task_struct *secondary_current;
> -bool has_big_cores;
> -bool coregroup_enabled;
> -bool thread_group_shares_l2;
> -bool thread_group_shares_l3;
> +bool has_big_cores __read_mostly;
> +bool coregroup_enabled __read_mostly;
> +bool thread_group_shares_l2 __read_mostly;
> +bool thread_group_shares_l3 __read_mostly;
>  
>  DEFINE_PER_CPU(cpumask_var_t, cpu_sibling_map);
>  DEFINE_PER_CPU(cpumask_var_t, cpu_smallcore_map);
> @@ -987,7 +987,7 @@ static int __init init_thread_group_cache_map(int cpu, int cache_property)
>  	return 0;
>  }
>  
> -static bool shared_caches;
> +static bool shared_caches __read_mostly;
>  DEFINE_STATIC_KEY_FALSE(powerpc_asym_packing);
>  
>  #ifdef CONFIG_SCHED_SMT
> -- 
> 2.31.1