On Wed 07-07-21 22:14:43, Ohhoon Kwon wrote:
> 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>
> Reviewed-by: David Hildenbrand <david@xxxxxxxxxx>
I would simply fold that into the first patch but a separate patch is
also OK.
Acked-by: Michal Hocko <mhocko@xxxxxxxx>
Thanks
> ---
> 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
--
Michal Hocko
SUSE Labs
