[PATCH v4 1/3] mm: sparse: pass section_nr to section_mark_present

From: Ohhoon Kwon
Date: Wed Jul 07 2021 - 11:05:48 EST


With CONFIG_SPARSEMEM_EXTREME enabled, __section_nr() which converts
mem_section to section_nr could be costly since it iterates all
section roots to check if the given mem_section is in its range.

Since both callers of section_mark_present already know section_nr,
let's also pass section_nr as well as mem_section in order to reduce
costly translation.

Signed-off-by: Ohhoon Kwon <ohoono.kwon@xxxxxxxxxxx>
Acked-by: Mike Rapoport <rppt@xxxxxxxxxxxxx>
Acked-by: Michal Hocko <mhocko@xxxxxxxx>
Reviewed-by: David Hildenbrand <david@xxxxxxxxxx>
---
mm/sparse.c | 9 ++++-----
1 file changed, 4 insertions(+), 5 deletions(-)

diff --git a/mm/sparse.c b/mm/sparse.c
index 6326cdf36c4f..8018ee7fcda5 100644
--- a/mm/sparse.c
+++ b/mm/sparse.c
@@ -187,10 +187,9 @@ void __meminit mminit_validate_memmodel_limits(unsigned long *start_pfn,
* those loops early.
*/
unsigned long __highest_present_section_nr;
-static void section_mark_present(struct mem_section *ms)
+static void __section_mark_present(struct mem_section *ms,
+ unsigned long section_nr)
{
- unsigned long section_nr = __section_nr(ms);
-
if (section_nr > __highest_present_section_nr)
__highest_present_section_nr = section_nr;

@@ -280,7 +279,7 @@ static void __init memory_present(int nid, unsigned long start, unsigned long en
if (!ms->section_mem_map) {
ms->section_mem_map = sparse_encode_early_nid(nid) |
SECTION_IS_ONLINE;
- section_mark_present(ms);
+ __section_mark_present(ms, section);
}
}
}
@@ -934,7 +933,7 @@ int __meminit sparse_add_section(int nid, unsigned long start_pfn,

ms = __nr_to_section(section_nr);
set_section_nid(section_nr, nid);
- section_mark_present(ms);
+ __section_mark_present(ms, section_nr);

/* Align memmap to section boundary in the subsection case */
if (section_nr_to_pfn(section_nr) != start_pfn)
--
2.17.1