On Thu, Dec 20, 2018 at 03:50:29PM -0800, Alexander Duyck wrote:
>On Thu, 2018-11-22 at 17:48 +0800, Wei Yang wrote:
>> When DEFERRED_STRUCT_PAGE_INIT is configured, only the first section of
>> each node's highest zone is initialized before defer stage.
>>
>> static_init_pgcnt is used to store the number of pages like this:
>>
>> pgdat->static_init_pgcnt = min_t(unsigned long, PAGES_PER_SECTION,
>> pgdat->node_spanned_pages);
>>
>> because we don't want to overflow zone's range.
>>
>> But this is not necessary, since defer_init() is called like this:
>>
>> memmap_init_zone()
>> for pfn in [start_pfn, end_pfn)
>> defer_init(pfn, end_pfn)
>>
>> In case (pgdat->node_spanned_pages < PAGES_PER_SECTION), the loop would
>> stop before calling defer_init().
>>
>> BTW, comparing PAGES_PER_SECTION with node_spanned_pages is not correct,
>> since nr_initialised is zone based instead of node based. Even
>> node_spanned_pages is bigger than PAGES_PER_SECTION, its highest zone
>> would have pages less than PAGES_PER_SECTION.
>>
>> Signed-off-by: Wei Yang <richard.weiyang@xxxxxxxxx>
>
>This all seems to make sense to me, and appears to be a valid
>improvement.
>
>Reviewed-by: Alexander Duyck <alexander.h.duyck@xxxxxxxxxxxxxxx>
Thanks :-)
>
>> ---
>> include/linux/mmzone.h | 2 --
>> mm/page_alloc.c | 13 ++++++-------
>> 2 files changed, 6 insertions(+), 9 deletions(-)
>>
>> diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
>> index ae7a830a21eb..68d7b558924b 100644
>> --- a/include/linux/mmzone.h
>> +++ b/include/linux/mmzone.h
>> @@ -692,8 +692,6 @@ typedef struct pglist_data {
>> * is the first PFN that needs to be initialised.
>> */
>> unsigned long first_deferred_pfn;
>> - /* Number of non-deferred pages */
>> - unsigned long static_init_pgcnt;
>> #endif /* CONFIG_DEFERRED_STRUCT_PAGE_INIT */
>>
>> #ifdef CONFIG_TRANSPARENT_HUGEPAGE
>> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
>> index 76e12179cd5e..b542d82400cf 100644
>> --- a/mm/page_alloc.c
>> +++ b/mm/page_alloc.c
>> @@ -326,8 +326,13 @@ defer_init(int nid, unsigned long pfn, unsigned long end_pfn)
>> /* Always populate low zones for address-constrained allocations */
>> if (end_pfn < pgdat_end_pfn(NODE_DATA(nid)))
>> return false;
>> +
>> + /*
>> + * We start only with one section of pages, more pages are added as
>> + * needed until the rest of deferred pages are initialized.
>> + */
>> nr_initialised++;
>> - if ((nr_initialised > NODE_DATA(nid)->static_init_pgcnt) &&
>> + if ((nr_initialised > PAGES_PER_SECTION) &&
>> (pfn & (PAGES_PER_SECTION - 1)) == 0) {
>> NODE_DATA(nid)->first_deferred_pfn = pfn;
>> return true;
>> @@ -6451,12 +6456,6 @@ static void __ref alloc_node_mem_map(struct pglist_data *pgdat) { }
>> #ifdef CONFIG_DEFERRED_STRUCT_PAGE_INIT
>> static inline void pgdat_set_deferred_range(pg_data_t *pgdat)
>> {
>> - /*
>> - * We start only with one section of pages, more pages are added as
>> - * needed until the rest of deferred pages are initialized.
>> - */
>> - pgdat->static_init_pgcnt = min_t(unsigned long, PAGES_PER_SECTION,
>> - pgdat->node_spanned_pages);
>> pgdat->first_deferred_pfn = ULONG_MAX;
>> }
>> #else
--
Wei Yang
Help you, Help me
