On Fri, Jan 13, 2023 at 04:26:59PM +0800, Peng Zhang wrote:
> memblock_merge_regions() is called after regions have been modified to
> merge the neighboring compatible regions. That will check all regions
> but most checks is useless.
>
> Most of the time we only insert one or a few new regions, or modify one
> or a few regions. At this time, we don't need to check all regions. We
> only need to check the changed regions, because other not related
> regions cannot be merged. So this patch add two parameters to
> memblock_merge_regions() to indicate the lower and upper boundary to scan.
>
> Signed-off-by: Peng Zhang <zhangpeng.00@xxxxxxxxxxxxx>
> ---
> mm/memblock.c | 36 ++++++++++++++++++++++++------------
> 1 file changed, 24 insertions(+), 12 deletions(-)
>
> diff --git a/mm/memblock.c b/mm/memblock.c
> index cb92770ac22e..e19eb08efc73 100644
> --- a/mm/memblock.c
> +++ b/mm/memblock.c
> @@ -523,15 +523,18 @@ static int __init_memblock memblock_double_array(struct memblock_type *type,
> /**
> * memblock_merge_regions - merge neighboring compatible regions
> * @type: memblock type to scan
> - *
> - * Scan @type and merge neighboring compatible regions.
> + * @start_rgn: start scanning from (@start_rgn - 1)
> + * @end_rgn: end scanning at (@end_rgn - 1)
> + * Scan @type and merge neighboring compatible regions in [@start_rgn - 1, @end_rgn)
> */
> -static void __init_memblock memblock_merge_regions(struct memblock_type *type)
> +static void __init_memblock memblock_merge_regions(struct memblock_type *type,
> + int start_rgn,
> + int end_rgn)
Make start_rgn and end_rgn unsigned longs and ...
> {
> - int i = 0;
> + int i = max(start_rgn - 1, 0);
... open code max() as
if (start_rgn)
i = start_rgn;
> - /* cnt never goes below 1 */
> - while (i < type->cnt - 1) {
> + end_rgn = min(end_rgn, (int)type->cnt - 1);
... and drop the casting here.
> + while (i < end_rgn) {
> struct memblock_region *this = &type->regions[i];
> struct memblock_region *next = &type->regions[i + 1];
>
> @@ -548,6 +551,7 @@ static void __init_memblock memblock_merge_regions(struct memblock_type *type)
> /* move forward from next + 1, index of which is i + 2 */
> memmove(next, next + 1, (type->cnt - (i + 2)) * sizeof(*next));
> type->cnt--;
> + end_rgn--;
> }
> }
>
> @@ -604,7 +608,7 @@ static int __init_memblock memblock_add_range(struct memblock_type *type,
> bool insert = false;
> phys_addr_t obase = base;
> phys_addr_t end = base + memblock_cap_size(base, &size);
> - int idx, start_idx, nr_new;
> + int idx, start_idx, nr_new, start_rgn = -1, end_rgn;
> struct memblock_region *rgn;
>
> if (!size)
> @@ -659,10 +663,14 @@ static int __init_memblock memblock_add_range(struct memblock_type *type,
> #endif
> WARN_ON(flags != rgn->flags);
> nr_new++;
> - if (insert)
> + if (insert) {
> + if (start_rgn == -1)
you can initialize start_rgn with 0 and use if(!start_rgn) here.
> + start_rgn = idx;
> + end_rgn = idx + 1;
> memblock_insert_region(type, idx++, base,
> rbase - base, nid,
> flags);
> + }
> }
> /* area below @rend is dealt with, forget about it */
> base = min(rend, end);
> @@ -671,9 +679,13 @@ static int __init_memblock memblock_add_range(struct memblock_type *type,
> /* insert the remaining portion */
> if (base < end) {
> nr_new++;
> - if (insert)
> + if (insert) {
> + if (start_rgn == -1)
Ditto.
> + start_rgn = idx;
> + end_rgn = idx + 1;
> memblock_insert_region(type, idx, base, end - base,
> nid, flags);
> + }
> }
>
> if (!nr_new)
> @@ -690,7 +702,7 @@ static int __init_memblock memblock_add_range(struct memblock_type *type,
> insert = true;
> goto repeat;
> } else {
> - memblock_merge_regions(type);
> + memblock_merge_regions(type, start_rgn, end_rgn);
> return 0;
> }
> }
> @@ -927,7 +939,7 @@ static int __init_memblock memblock_setclr_flag(phys_addr_t base,
> r->flags &= ~flag;
> }
>
> - memblock_merge_regions(type);
> + memblock_merge_regions(type, start_rgn, end_rgn);
> return 0;
> }
>
> @@ -1300,7 +1312,7 @@ int __init_memblock memblock_set_node(phys_addr_t base, phys_addr_t size,
> for (i = start_rgn; i < end_rgn; i++)
> memblock_set_region_node(&type->regions[i], nid);
>
> - memblock_merge_regions(type);
> + memblock_merge_regions(type, start_rgn, end_rgn);
> #endif
> return 0;
> }
> --
> 2.20.1
>
--
Sincerely yours,
Mike.
