On Tue, Mar 27, 2018 at 03:47:40PM -0700, Andrew Morton wrote:
>On Tue, 27 Mar 2018 11:57:07 +0800 Wei Yang <richard.weiyang@xxxxxxxxx> wrote:
>
>> find_min_pfn_for_node() iterate on pfn range to find the minimum pfn for a
>> node. The memblock_region in memblock_type are already ordered, which means
>> the first hit in iteration is the minimum pfn.
>>
>> This patch returns the fist hit instead of iterating the whole regions.
>>
>> ...
>>
>> --- a/mm/page_alloc.c
>> +++ b/mm/page_alloc.c
>> @@ -6365,14 +6365,14 @@ unsigned long __init node_map_pfn_alignment(void)
>> /* Find the lowest pfn for a node */
>> static unsigned long __init find_min_pfn_for_node(int nid)
>> {
>> - unsigned long min_pfn = ULONG_MAX;
>> - unsigned long start_pfn;
>> + unsigned long min_pfn;
>> int i;
>>
>> - for_each_mem_pfn_range(i, nid, &start_pfn, NULL, NULL)
>> - min_pfn = min(min_pfn, start_pfn);
>> + for_each_mem_pfn_range(i, nid, &min_pfn, NULL, NULL) {
>> + break;
>> + }
>
>That would be the weirdest-looking code snippet in mm/!
>
You mean the only break in a for_each loop? Hmm..., this is really not that
nice. Haven't noticed could get a "best" in this way :-)
>Can't we just use a single and simple call to __next_mem_pfn_range(),
>or something like that?
>
Sounds a better choice, if you like this version, I would rearrange the patch
and send v2.
Have a nice day~
>>
>> ...
>>
--
Wei Yang
Help you, Help me
