Re: [Patch v2 2/2] mm/page_alloc: not necessary to multiply MAX_NODE_LOAD

[Wei Yang <richard.weiyang@gmail.com>]

On Fri, Apr 08, 2022 at 10:09:48AM +0200, David Hildenbrand wrote:
>On 08.04.22 04:59, Wei Yang wrote:
>> Since we just increase a constance of 1 to node penalty, it is not
>> necessary to multiply MAX_NODE_LOAD for preference.
>> 
>> This patch also remove the definition.
>> 
>> [vbabka@suse.cz: suggests]
>> 
>> Signed-off-by: Wei Yang <richard.weiyang@gmail.com>
>> CC: Vlastimil Babka <vbabka@suse.cz>
>> CC: David Hildenbrand <david@redhat.com>
>> CC: Oscar Salvador <osalvador@suse.de>
>> ---
>>  mm/page_alloc.c | 3 +--
>>  1 file changed, 1 insertion(+), 2 deletions(-)
>> 
>> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
>> index 86b6573fbeb5..ca6a127bbc26 100644
>> --- a/mm/page_alloc.c
>> +++ b/mm/page_alloc.c
>> @@ -6170,7 +6170,6 @@ int numa_zonelist_order_handler(struct ctl_table *table, int write,
>>  }
>>  
>>  
>> -#define MAX_NODE_LOAD (nr_online_nodes)
>>  static int node_load[MAX_NUMNODES];
>>  
>>  /**
>> @@ -6217,7 +6216,7 @@ int find_next_best_node(int node, nodemask_t *used_node_mask)
>>  			val += PENALTY_FOR_NODE_WITH_CPUS;
>>  
>>  		/* Slight preference for less loaded node */
>> -		val *= (MAX_NODE_LOAD*MAX_NUMNODES);
>> +		val *= MAX_NUMNODES;
>>  		val += node_load[n];
>>  
>>  		if (val < min_val) {
>
>I feel like this should be squashed into the previous patch. It has the
>same effect of making this code independent of nr_online_nodes. And I
>had to scratch my head a couple of times in patch #1 why the change in
>patch #1 is fine with thus remaining in place.
>
>
>Having that said, I consider this code highly unnecessary
>over-complicated at first sight. Removing some of the magic most
>certainly is very welcome.
>
>This semantics of the global variable node_load[] remains mostly
>mysterious for me.
>

So the suggestion is a v3 with #1 and #2 squashed?

>-- 
>Thanks,
>
>David / dhildenb

-- 
Wei Yang
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