Commit d3795dc9 authored Apr 07, 2024 by Liam R. Howlett Committed by Peng Zhang Apr 07, 2024

maple_tree: mtree_range_walk() clean up

mainline inclusion
from mainline-v6.8-rc1
commit a3c63c8c5df6406e79490456a1fc41a287676070
category: performance
bugzilla: https://gitee.com/openeuler/kernel/issues/I9EHBO
CVE: NA

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=a3c63c8c5df6406e79490456a1fc41a287676070

--------------------------------

mtree_range_walk() needed to be updated to avoid checking if there was a
pivot value.  On closer examination, the code could avoid setting min or
max in certain scenarios.  The commit removes the extra check for
pivot[offset] before setting max and only sets max when necessary.  It
also only sets min if it is necessary by checking offset 0 prior to the
loop (as it has always done).

The commit also drops a dead node check since the end of the node will
return the array size when the last slot is occupied (by a potential reuse
in a dead node).  The data will be discarded later if the node is marked
dead.

Benchmarking these changes results in an increase in performance of 5.45%
using the BENCH_WALK in the maple tree test code.

Link: https://lkml.kernel.org/r/20231101171629.3612299-13-Liam.Howlett@oracle.com


Signed-off-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Cc: Peng Zhang <zhangpeng.00@bytedance.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: ZhangPeng <zhangpeng362@huawei.com>

parent f0b3d94c

lib/maple_tree.c

+12 −15

Original line number	Diff line number	Diff line
		@@ -2806,32 +2806,29 @@ static inline void mtree_range_walk(struct ma_state mas)
		min = mas->min;
		max = mas->max;
		do {
		offset = 0;
		last = next;
		node = mte_to_node(next);
		type = mte_node_type(next);
		pivots = ma_pivots(node, type);
		end = ma_data_end(node, type, pivots, max);
		if (unlikely(ma_dead_node(node)))
		goto dead_node;

		if (pivots[offset] >= mas->index) {
		prev_max = max;
		prev_min = min;
		max = pivots[offset];
		prev_max = max;
		if (pivots[0] >= mas->index) {
		offset = 0;
		max = pivots[0];
		goto next;
		}

		do {
		offset = 1;
		while (offset < end) {
		if (pivots[offset] >= mas->index) {
		max = pivots[offset];
		break;
		}
		offset++;
		} while ((offset < end) && (pivots[offset] < mas->index));
		}

		prev_min = min;
		min = pivots[offset - 1] + 1;
		prev_max = max;
		if (likely(offset < end && pivots[offset]))
		max = pivots[offset];

		next:
		slots = ma_slots(node, type);
		next = mt_slot(mas->tree, slots, offset);