Messages in this thread Patch in this message | | | From | Ohhoon Kwon <> | Subject | [PATCH v2 1/3] mm: sparse: pass section_nr to section_mark_present | Date | Mon, 5 Jul 2021 17:55:36 +0900 |
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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.
On the other hand, __nr_to_section() which converts section_nr to mem_section can be done in O(1).
Let's pass section_nr instead of mem_section ptr to section_mark_present() in order to reduce needless iterations.
Signed-off-by: Ohhoon Kwon <ohoono.kwon@samsung.com> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: Mike Rapoport <rppt@linux.ibm.com> Reviewed-by: David Hildenbrand <david@redhat.com> --- mm/sparse.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-)
diff --git a/mm/sparse.c b/mm/sparse.c index 6326cdf36c4f..b4fae2fc6276 100644 --- a/mm/sparse.c +++ b/mm/sparse.c @@ -187,13 +187,14 @@ 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(unsigned long section_nr) { - unsigned long section_nr = __section_nr(ms); + struct mem_section *ms; if (section_nr > __highest_present_section_nr) __highest_present_section_nr = section_nr; + ms = __nr_to_section(section_nr); ms->section_mem_map |= SECTION_MARKED_PRESENT; } @@ -280,7 +281,7 @@ 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(section); } } } @@ -934,7 +935,7 @@ 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(section_nr); /* Align memmap to section boundary in the subsection case */ if (section_nr_to_pfn(section_nr) != start_pfn) -- 2.17.1
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