linux-kernel - Applied "regmap: rbtree: When adding a reg do a bsearch for target node" to the regmap tree

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Date:	Fri, 23 Oct 2015 08:10:27 +0900
From:	Mark Brown <broonie@...nel.org>
To:	Nikesh Oswal <Nikesh.Oswal@...fsonmicro.com>,
	Mark Brown <broonie@...nel.org>
Cc:	linux-kernel@...r.kernel.org
Subject: Applied "regmap: rbtree: When adding a reg do a bsearch for target node" to the regmap tree

The patch

   regmap: rbtree: When adding a reg do a bsearch for target node

has been applied to the regmap tree at

   git://git.kernel.org/pub/scm/linux/kernel/git/broonie/regmap.git 

All being well this means that it will be integrated into the linux-next
tree (usually sometime in the next 24 hours) and sent to Linus during
the next merge window (or sooner if it is a bug fix), however if
problems are discovered then the patch may be dropped or reverted.  

You may get further e-mails resulting from automated or manual testing
and review of the tree, please engage with people reporting problems and
send followup patches addressing any issues that are reported if needed.

If any updates are required or you are submitting further changes they
should be sent as incremental updates against current git, existing
patches will not be replaced.

Please add any relevant lists and maintainers to the CCs when replying
to this mail.

Thanks,
Mark

>From c164cfba7c6569d01a83cb6fdde0cb1cadf72cf8 Mon Sep 17 00:00:00 2001
From: Nikesh Oswal <Nikesh.Oswal@...fsonmicro.com>
Date: Wed, 21 Oct 2015 14:16:14 +0100
Subject: [PATCH] regmap: rbtree: When adding a reg do a bsearch for target
 node

A binary search is much more efficient rather than iterating
over the rbtree in ascending order which the current code is
doing.

During initialisation the reg defaults are written to the
cache in a large chunk and these are always sorted in the
ascending order so for this situation ideally we should have
iterated the rbtree in descending order.

But at runtime the drivers may write into the cache in any
random order so this patch selects to use a bsearch to give
an optimal runtime performance and also at initialisation
time when reg defaults are written the performance of binary
search would be much better than iterating in ascending order
which the current code was doing.

Signed-off-by: Nikesh Oswal <Nikesh.Oswal@...fsonmicro.com>
Signed-off-by: Mark Brown <broonie@...nel.org>
---
 drivers/base/regmap/regcache-rbtree.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/drivers/base/regmap/regcache-rbtree.c b/drivers/base/regmap/regcache-rbtree.c
index 56486d9..353f602 100644
--- a/drivers/base/regmap/regcache-rbtree.c
+++ b/drivers/base/regmap/regcache-rbtree.c
@@ -413,8 +413,8 @@ static int regcache_rbtree_write(struct regmap *map, unsigned int reg,
 		max = reg + max_dist;

 		/* look for an adjacent register to the one we are about to add */
-		for (node = rb_first(&rbtree_ctx->root); node;
-		     node = rb_next(node)) {
+		node = rbtree_ctx->root.rb_node;
+		while (node) {
 			rbnode_tmp = rb_entry(node, struct regcache_rbtree_node,
 					      node);

@@ -425,6 +425,11 @@ static int regcache_rbtree_write(struct regmap *map, unsigned int reg,
 				new_base_reg = min(reg, base_reg);
 				new_top_reg = max(reg, top_reg);
 			} else {
+				if (max < base_reg)
+					node = node->rb_left;
+				else
+					node = node->rb_right;
+
 				continue;
 			}

-- 
2.6.1

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