Re: [PATCH 1/2] mm/sparse: pass the __highest_present_section_nr + 1 to alloc_func()

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

On Mon, Mar 26, 2018 at 01:56:50PM -0700, David Rientjes wrote:
>On Mon, 26 Mar 2018, Wei Yang wrote:
>
>> In 'commit c4e1be9ec113 ("mm, sparsemem: break out of loops early")',
>> __highest_present_section_nr is introduced to reduce the loop counts for
>> present section. This is also helpful for usemap and memmap allocation.
>> 
>> This patch uses __highest_present_section_nr + 1 to optimize the loop.
>> 
>> Signed-off-by: Wei Yang <richard.weiyang@gmail.com>
>> ---
>>  mm/sparse.c | 2 +-
>>  1 file changed, 1 insertion(+), 1 deletion(-)
>> 
>> diff --git a/mm/sparse.c b/mm/sparse.c
>> index 7af5e7a92528..505050346249 100644
>> --- a/mm/sparse.c
>> +++ b/mm/sparse.c
>> @@ -561,7 +561,7 @@ static void __init alloc_usemap_and_memmap(void (*alloc_func)
>>  		map_count = 1;
>>  	}
>>  	/* ok, last chunk */
>> -	alloc_func(data, pnum_begin, NR_MEM_SECTIONS,
>> +	alloc_func(data, pnum_begin, __highest_present_section_nr+1,
>>  						map_count, nodeid_begin);
>>  }
>>  
>
>What happens if s/NR_MEM_SECTIONS/pnum/?

I have tried this :-)

The last pnum is -1 from next_present_section_nr().

-- 
Wei Yang
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