Commit 28e1a8f4 authored Jun 15, 2022 by Jinyu Tang Committed by Mike Rapoport Jun 30, 2022

memblock: avoid some repeat when add new range



The worst case is that the new memory range overlaps all existing
regions, which requires type->cnt + 1 empty struct memblock_region slots in
the type->regions array.
So if type->cnt + 1 + type->cnt is less than type->max, we can insert
regions directly rather than calculate the needed amount before the
insertion.
And becase of merge operation in the end of function, tpye->cnt will
increase slowly for many cases.

This change allows to avoid unnecessary repeat of memblock ranges traversal
for many cases when adding new memory range.

Signed-off-by: Jinyu Tang <tjytimi@163.com>
[rppt: massaged comment and changelog text]
Signed-off-by: Mike Rapoport <rppt@linux.ibm.com>

parent 03c765b0

mm/memblock.c

+11 −0

Original line number	Diff line number	Diff line
		@@ -593,6 +593,17 @@ static int __init_memblock memblock_add_range(struct memblock_type *type,
		type->total_size = size;
		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