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Subject[PATCH] regmap: Optimize the lookup path to use binary search
Date
Since there are more lookups than insertions in a typical
scenario, optimize the linear search into a binary search. For
this to work, we need to keep reg_defaults sorted upon
insertions, for now be lazy and use sort().

Signed-off-by: Dimitris Papastamos <dp@opensource.wolfsonmicro.com>
---
drivers/base/regmap/regcache.c | 29 ++++++++++++++++++++++++-----
1 files changed, 24 insertions(+), 5 deletions(-)

diff --git a/drivers/base/regmap/regcache.c b/drivers/base/regmap/regcache.c
index f32c08c..b10e38f 100644
--- a/drivers/base/regmap/regcache.c
+++ b/drivers/base/regmap/regcache.c
@@ -12,6 +12,7 @@

#include <linux/slab.h>
#include <trace/events/regmap.h>
+#include <linux/sort.h>

#include "internal.h"

@@ -356,14 +357,30 @@ unsigned int regcache_get_val(const void *base, unsigned int idx,

int regcache_lookup_reg(struct regmap *map, unsigned int reg)
{
- unsigned int i;
-
- for (i = 0; i < map->num_reg_defaults; i++)
- if (map->reg_defaults[i].reg == reg)
- return i;
+ unsigned int min, max, index;
+
+ min = 0;
+ max = map->num_reg_defaults - 1;
+ do {
+ index = (min + max) / 2;
+ if (map->reg_defaults[index].reg == reg)
+ return index;
+ if (map->reg_defaults[index].reg < reg)
+ min = index + 1;
+ else
+ max = index;
+ } while (min <= max);
return -1;
}

+static int regcache_insert_cmp(const void *a, const void *b)
+{
+ const struct reg_default *_a = a;
+ const struct reg_default *_b = b;
+
+ return _a->reg - _b->reg;
+}
+
int regcache_insert_reg(struct regmap *map, unsigned int reg,
unsigned int val)
{
@@ -378,5 +395,7 @@ int regcache_insert_reg(struct regmap *map, unsigned int reg,
map->num_reg_defaults++;
map->reg_defaults[map->num_reg_defaults - 1].reg = reg;
map->reg_defaults[map->num_reg_defaults - 1].def = val;
+ sort(map->reg_defaults, map->num_reg_defaults,
+ sizeof(struct reg_default), regcache_insert_cmp, NULL);
return 0;
}
--
1.7.6.4


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