Commit 6e1b6d0d authored by Peng Zhang's avatar Peng Zhang Committed by Li Zetao
Browse files

maple_tree: avoid checking other gaps after getting the largest gap 

mainline inclusion
from mainline-v6.8-rc1
commit 7e552dcd803f4ff60165271c573ab2e38d15769f
category: performance
bugzilla: https://gitee.com/openeuler/kernel/issues/I9N4V1
CVE: NA

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=7e552dcd803f4ff60165271c573ab2e38d15769f

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The last range stored in maple tree is typically quite large.  By checking
if it exceeds the sum of the remaining ranges in that node, it is possible
to avoid checking all other gaps.

Running the maple tree test suite in user mode almost always results in a
near 100% hit rate for this optimization.

Link: https://lkml.kernel.org/r/20231215074632.82045-1-zhangpeng.00@bytedance.com


Signed-off-by: default avatarPeng Zhang <zhangpeng.00@bytedance.com>
Reviewed-by: default avatarLiam R. Howlett <Liam.Howlett@oracle.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLi Zetao <lizetao1@huawei.com>
parent 1087e901

lib/maple_tree.c

+3 −0
Original line number Diff line number Diff line
@@ -1547,6 +1547,9 @@ static unsigned long mas_leaf_max_gap(struct ma_state *mas) 
		gap = ULONG_MAX - pivots[max_piv];

		if (gap > max_gap)

			max_gap = gap;



		if (max_gap > pivots[max_piv] - mas->min)

			return max_gap;

	}



	for (; i <= max_piv; i++) {