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Date:   Thu, 10 Mar 2022 06:48:21 +0100
From:   Oscar Salvador <osalvador@suse.de>
To:     "Huang, Ying" <ying.huang@intel.com>
Cc:     Andrew Morton <akpm@linux-foundation.org>,
        Dave Hansen <dave.hansen@linux.intel.com>,
        Abhishek Goel <huntbag@linux.vnet.ibm.com>, linux-mm@kvack.org,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH] mm: Only re-generate demotion targets when a numa node
 changes its N_CPU state
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References: <20220309144644.4278-1-osalvador@suse.de>
 <87bkyefxnq.fsf@yhuang6-desk2.ccr.corp.intel.com>
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On Thu, Mar 10, 2022 at 08:39:53AM +0800, Huang, Ying wrote:
> We need to call set_migration_target_nodes() during system boot
> somewhere, either here or in init_mm_internals().

Hi Huang Ying,

vmstat_cpu_online() already gets called during boot:

static struct cpuhp_step cpuhp_hp_states[] = {
...
	#ifdef CONFIG_SMP
	[CPUHP_CREATE_THREADS]= {
		.name			= "threads:prepare",
		.startup.single		= smpboot_create_threads,
		.teardown.single	= NULL,
		.cant_stop		= true,
	},
...

smpboot_create_threads
 __smpboot_create_thread
  smpboot_thread_fn
   ht->thread_fn() 
    cpuhp_thread_fun
     cpuhp_invoke_callback
      vmstat_cpu_online

That for every CPU that is brought up during boot.

So unless I am missing something, I would say we are already covered
there, right?


-- 
Oscar Salvador
SUSE Labs