Re: [PATCH v6 2/2] memory tier: create CPUless memory tiers after obtaining HMAT info

[Huang, Ying]

"Ho-Ren (Jack) Chuang" <horenchuang@bytedance.com> writes:

[snip]

> @@ -655,6 +672,34 @@ void mt_put_memory_types(struct list_head *memory_types)
>  }
>  EXPORT_SYMBOL_GPL(mt_put_memory_types);
>  
> +/*
> + * This is invoked via `late_initcall()` to initialize memory tiers for
> + * CPU-less memory nodes after driver initialization, which is
> + * expected to provide `adistance` algorithms.
> + */
> +static int __init memory_tier_late_init(void)
> +{
> +     int nid;
> +
> +     mutex_lock(&memory_tier_lock);
> +     for_each_node_state(nid, N_MEMORY)
> +             if (!node_state(nid, N_CPU) &&
> +                     node_memory_types[nid].memtype == NULL)

Think about this again.  It seems that it is better to check
"node_memory_types[nid].memtype == NULL" only here.  Because for all
node with N_CPU in memory_tier_init(), "node_memory_types[nid].memtype"
will be !NULL.  And it's possible (in theory) that some nodes becomes
"node_state(nid, N_CPU) == true" between memory_tier_init() and
memory_tier_late_init().

Otherwise, Looks good to me.  Feel free to add

Reviewed-by: "Huang, Ying" <ying.huang@intel.com>

in the future version.

> +                     /*
> +                      * Some device drivers may have initialized memory tiers
> +                      * between `memory_tier_init()` and 
> `memory_tier_late_init()`,
> +                      * potentially bringing online memory nodes and
> +                      * configuring memory tiers. Exclude them here.
> +                      */
> +                     set_node_memory_tier(nid);
> +
> +     establish_demotion_targets();
> +     mutex_unlock(&memory_tier_lock);
> +
> +     return 0;
> +}
> +late_initcall(memory_tier_late_init);
> +

[snip]

--
Best Regards,
Huang, Ying