Re: [PATCH 3/3] mm/mm_init.c: not always search next deferred_init_pfn from very beginning

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

On Mon, Jun 03, 2024 at 09:27:10AM +0300, Mike Rapoport wrote:
>On Fri, May 31, 2024 at 12:26:13AM +0000, Wei Yang wrote:
>> In function deferred_init_memmap(), we call
>> deferred_init_mem_pfn_range_in_zone() to get the next deferred_init_pfn.
>> But we always search it from the very beginning.
>> 
>> Since we save the index in i, we can leverage this to search from i next
>> time.
>> 
>> Signed-off-by: Wei Yang <richard.weiyang@gmail.com>
>> ---
>>  include/linux/memblock.h | 19 -------------------
>>  mm/mm_init.c             | 21 ++++++++++++---------
>>  2 files changed, 12 insertions(+), 28 deletions(-)
>> 
>> diff --git a/include/linux/memblock.h b/include/linux/memblock.h
>> index 6cf18dc2b4d0..45cac33334c8 100644
>> --- a/include/linux/memblock.h
>> +++ b/include/linux/memblock.h
>> @@ -299,25 +299,6 @@ void __next_mem_pfn_range(int *idx, int nid, unsigned long *out_start_pfn,
>>  void __next_mem_pfn_range_in_zone(u64 *idx, struct zone *zone,
>>  				  unsigned long *out_spfn,
>>  				  unsigned long *out_epfn);
>> -/**
>> - * for_each_free_mem_pfn_range_in_zone - iterate through zone specific free
>> - * memblock areas
>> - * @i: u64 used as loop variable
>> - * @zone: zone in which all of the memory blocks reside
>> - * @p_start: ptr to phys_addr_t for start address of the range, can be %NULL
>> - * @p_end: ptr to phys_addr_t for end address of the range, can be %NULL
>> - *
>> - * Walks over free (memory && !reserved) areas of memblock in a specific
>> - * zone. Available once memblock and an empty zone is initialized. The main
>> - * assumption is that the zone start, end, and pgdat have been associated.
>> - * This way we can use the zone to determine NUMA node, and if a given part
>> - * of the memblock is valid for the zone.
>> - */
>> -#define for_each_free_mem_pfn_range_in_zone(i, zone, p_start, p_end)	\
>> -	for (i = 0,							\
>> -	     __next_mem_pfn_range_in_zone(&i, zone, p_start, p_end);	\
>> -	     i != U64_MAX;					\
>> -	     __next_mem_pfn_range_in_zone(&i, zone, p_start, p_end))
>>  
>>  /**
>>   * for_each_free_mem_pfn_range_in_zone_from - iterate through zone specific
>> diff --git a/mm/mm_init.c b/mm/mm_init.c
>> index d05a4c38310f..ec17bf93f946 100644
>> --- a/mm/mm_init.c
>> +++ b/mm/mm_init.c
>> @@ -2023,18 +2023,21 @@ static unsigned long  __init deferred_init_pages(struct zone *zone,
>>   * return false indicating there are no valid ranges left.
>>   */
>>  static bool __init
>> -deferred_init_mem_pfn_range_in_zone(u64 *i, struct zone *zone,
>> +deferred_init_mem_pfn_range_in_zone_from(u64 *i, struct zone *zone,
>
>I don't think renaming this function is useful.
>The comment above it, on the other hand, needs update.
>

Not good at the description, below is my adjustment. Does it looks good to
you?

diff --git a/mm/mm_init.c b/mm/mm_init.c
index 1780567b5f6b..bc065728261d 100644
--- a/mm/mm_init.c
+++ b/mm/mm_init.c
@@ -2003,13 +2003,14 @@ static unsigned long __init deferred_init_pages(struct zone *zone,
 }
 
 /*
- * This function is meant to pre-load the iterator for the zone init.
+ * This function is meant to pre-load the iterator for the zone init from a
+ * given point. If it specifies to start from 0, do the initial iteration.
  * Specifically it walks through the ranges until we are caught up to the
  * first_init_pfn value and exits there. If we never encounter the value we
  * return false indicating there are no valid ranges left.
  */
-- 
Wei Yang
Help you, Help me