Hi,
On Wed, Oct 19, 2022 at 08:03:37PM +0800, Yajun Deng wrote:
> Subject: memblock: remove repeat round
Please make the patch subject more detailed. Say
membloc: don't run loop in memblock_add_range() twice
> There is no need round twice in memblock_add_range().
>
> We can call memblock_double_array() to extand the size if type->cnt no
^ extend
> less than type->max before memblock_insert_region(), otherwise we can
s/no less than/greater or equal to/
> insert the new region directly.
>
> Signed-off-by: Yajun Deng <yajun.deng@xxxxxxxxx>
> ---
> mm/memblock.c | 54 +++++++++++++++------------------------------------
> 1 file changed, 16 insertions(+), 38 deletions(-)
>
> diff --git a/mm/memblock.c b/mm/memblock.c
> index 511d4783dcf1..1679244b4a1a 100644
> --- a/mm/memblock.c
> +++ b/mm/memblock.c
> @@ -578,7 +578,6 @@ static int __init_memblock memblock_add_range(struct memblock_type *type,
> phys_addr_t base, phys_addr_t size,
> int nid, enum memblock_flags flags)
> {
> - bool insert = false;
> phys_addr_t obase = base;
> phys_addr_t end = base + memblock_cap_size(base, &size);
> int idx, nr_new;
> @@ -598,22 +597,6 @@ static int __init_memblock memblock_add_range(struct memblock_type *type,
> return 0;
> }
>
> - /*
> - * The worst case is when new range overlaps all existing regions,
> - * then we'll need type->cnt + 1 empty regions in @type. So if
> - * type->cnt * 2 + 1 is less than type->max, we know
> - * that there is enough empty regions in @type, and we can insert
> - * regions directly.
> - */
> - if (type->cnt * 2 + 1 < type->max)
> - insert = true;
> -
> -repeat:
> - /*
> - * The following is executed twice. Once with %false @insert and
> - * then with %true. The first counts the number of regions needed
> - * to accommodate the new area. The second actually inserts them.
> - */
> base = obase;
> nr_new = 0;
I believe nr_new variable is no longer needed, is it?
> @@ -635,10 +618,14 @@ static int __init_memblock memblock_add_range(struct memblock_type *type,
> #endif
> WARN_ON(flags != rgn->flags);
> nr_new++;
> - if (insert)
> - memblock_insert_region(type, idx++, base,
> - rbase - base, nid,
> - flags);
> +
> + if ((type->cnt >= type->max) &&
> + (memblock_double_array(type, obase, size) < 0))
if ((type->cnt >= type->max) &&
memblock_double_array(type, obase, size))
would be just fine.
I'd appreciate a comment above the if statement explaining when the
allocation is required.
> + return -ENOMEM;
> +
> + memblock_insert_region(type, idx++, base,
> + rbase - base, nid,
> + flags);
> }
> /* area below @rend is dealt with, forget about it */
> base = min(rend, end);
> @@ -647,28 +634,19 @@ static int __init_memblock memblock_add_range(struct memblock_type *type,
> /* insert the remaining portion */
> if (base < end) {
> nr_new++;
> - if (insert)
> - memblock_insert_region(type, idx, base, end - base,
> - nid, flags);
> + if ((type->cnt >= type->max) &&
> + (memblock_double_array(type, obase, size) < 0))
> + return -ENOMEM;
> +
> + memblock_insert_region(type, idx, base, end - base,
> + nid, flags);
> }
>
> if (!nr_new)
> return 0;
>
> - /*
> - * If this was the first round, resize array and repeat for actual
> - * insertions; otherwise, merge and return.
> - */
> - if (!insert) {
> - while (type->cnt + nr_new > type->max)
> - if (memblock_double_array(type, obase, size) < 0)
> - return -ENOMEM;
> - insert = true;
> - goto repeat;
> - } else {
> - memblock_merge_regions(type);
> - return 0;
> - }
> + memblock_merge_regions(type);
A blank line here would be nice.
> + return 0;
> }
>
> /**
> --
> 2.25.1
>
>
--
Sincerely yours,
Mike.
