Re: [PATCH v13 9/9] lib/nodemask: Optimize node_random for nodemask with single NUMA node

[Aneesh Kumar K V <aneesh.kumar@linux.ibm.com>]

On 8/9/22 8:43 AM, Huang, Ying wrote:
> "Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com> writes:
> 
>> The most common case for certain node_random usage (demotion nodemask) is with
>> nodemask weight 1. We can avoid calling get_random_init() in that case and
>> always return the only node set in the nodemask.
> 
> I think that this patch can sit between [5/9] and [6/9], just after it
> is used.
> 
>> Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
>> ---
>>  lib/nodemask.c | 15 ++++++++++++---
>>  1 file changed, 12 insertions(+), 3 deletions(-)
>>
>> diff --git a/lib/nodemask.c b/lib/nodemask.c
>> index e22647f5181b..c91a6b0404a5 100644
>> --- a/lib/nodemask.c
>> +++ b/lib/nodemask.c
>> @@ -20,12 +20,21 @@ EXPORT_SYMBOL(__next_node_in);
>>   */
>>  int node_random(const nodemask_t *maskp)
>>  {
>> -	int w, bit = NUMA_NO_NODE;
>> +	int w, bit;
>>  
>>  	w = nodes_weight(*maskp);
>> -	if (w)
>> +	switch (w) {
>> +	case 0:
>> +		bit = NUMA_NO_NODE;
>> +		break;
>> +	case 1:
>> +		bit = __first_node(maskp);
> 
> Per my understanding, first_node() is the formal API and we should use
> that?  Just like we use nodes_weight() instead of __nodes_weight().
> 

updated.

-aneesh