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Message-Id: <1495114829-3354-1-git-send-email-lenohou@gmail.com>
Date: Thu, 18 May 2017 21:40:28 +0800
From: Leno Hou <lenohou@...il.com>
To: linux-kernel@...r.kernel.org
Cc: andy.shevchenko@...il.com, akpm@...ux-foundation.org,
Leno Hou <lenohou@...il.com>
Subject: [PATCH v3 1/2] lib/btree.c: optimise the code by previously getpos function
Rework the getpos() helper function and use it to remove various
open-coded implemetnations of its funtionality.
v2 -> v3:
- getfill() returns no entry if not found the fill position
v1 -> v2:
- getpos() returns no entry if not found the key
Reviewed-by: Andy Shevchenko <andy.shevchenko@...il.com>
Signed-off-by: Leno Hou <lenohou@...il.com>
---
lib/btree.c | 79 +++++++++++++++++++++++++++++--------------------------------
1 file changed, 37 insertions(+), 42 deletions(-)
diff --git a/lib/btree.c b/lib/btree.c
index f93a945..b9dff18 100644
--- a/lib/btree.c
+++ b/lib/btree.c
@@ -238,6 +238,18 @@ static int keyzero(struct btree_geo *geo, unsigned long *key)
return 1;
}
+static int getpos(struct btree_geo *geo, unsigned long *node,
+ unsigned long *key)
+{
+ unsigned int i;
+
+ for (i = 0; i < geo->no_pairs; i++) {
+ if (keycmp(geo, node, i, key) <= 0)
+ return i;
+ }
+ return -ENOENT;
+}
+
void *btree_lookup(struct btree_head *head, struct btree_geo *geo,
unsigned long *key)
{
@@ -248,10 +260,8 @@ void *btree_lookup(struct btree_head *head, struct btree_geo *geo,
return NULL;
for ( ; height > 1; height--) {
- for (i = 0; i < geo->no_pairs; i++)
- if (keycmp(geo, node, i, key) <= 0)
- break;
- if (i == geo->no_pairs)
+ i = getpos(geo, node, key);
+ if (i < 0)
return NULL;
node = bval(geo, node, i);
if (!node)
@@ -278,10 +288,8 @@ int btree_update(struct btree_head *head, struct btree_geo *geo,
return -ENOENT;
for ( ; height > 1; height--) {
- for (i = 0; i < geo->no_pairs; i++)
- if (keycmp(geo, node, i, key) <= 0)
- break;
- if (i == geo->no_pairs)
+ i = getpos(geo, node, key);
+ if (i < 0)
return -ENOENT;
node = bval(geo, node, i);
if (!node)
@@ -326,10 +334,8 @@ void *btree_get_prev(struct btree_head *head, struct btree_geo *geo,
node = head->node;
for (height = head->height ; height > 1; height--) {
- for (i = 0; i < geo->no_pairs; i++)
- if (keycmp(geo, node, i, key) <= 0)
- break;
- if (i == geo->no_pairs)
+ i = getpos(geo, node, key);
+ if (i < 0)
goto miss;
oldnode = node;
node = bval(geo, node, i);
@@ -360,26 +366,17 @@ void *btree_get_prev(struct btree_head *head, struct btree_geo *geo,
}
EXPORT_SYMBOL_GPL(btree_get_prev);
-static int getpos(struct btree_geo *geo, unsigned long *node,
- unsigned long *key)
-{
- int i;
-
- for (i = 0; i < geo->no_pairs; i++) {
- if (keycmp(geo, node, i, key) <= 0)
- break;
- }
- return i;
-}
-
static int getfill(struct btree_geo *geo, unsigned long *node, int start)
{
- int i;
+ unsigned int i;
+
+ if (unlikely(start < 0))
+ return -ENOENT;
for (i = start; i < geo->no_pairs; i++)
if (!bval(geo, node, i))
- break;
- return i;
+ return i;
+ return -ENOENT;
}
/*
@@ -392,11 +389,9 @@ static unsigned long *find_level(struct btree_head *head, struct btree_geo *geo,
int i, height;
for (height = head->height; height > level; height--) {
- for (i = 0; i < geo->no_pairs; i++)
- if (keycmp(geo, node, i, key) <= 0)
- break;
+ i = getpos(geo, node, key);
- if ((i == geo->no_pairs) || !bval(geo, node, i)) {
+ if ((i < 0) || !bval(geo, node, i)) {
/* right-most key is too large, update it */
/* FIXME: If the right-most key on higher levels is
* always zero, this wouldn't be necessary. */
@@ -466,7 +461,7 @@ static int btree_insert_level(struct btree_head *head, struct btree_geo *geo,
/* two identical keys are not allowed */
BUG_ON(pos < fill && keycmp(geo, node, pos, key) == 0);
- if (fill == geo->no_pairs) {
+ if (fill < 0) {
/* need to split node */
unsigned long *new;
@@ -474,27 +469,27 @@ static int btree_insert_level(struct btree_head *head, struct btree_geo *geo,
if (!new)
return -ENOMEM;
err = btree_insert_level(head, geo,
- bkey(geo, node, fill / 2 - 1),
+ bkey(geo, node, geo->no_pairs / 2 - 1),
new, level + 1, gfp);
if (err) {
mempool_free(new, head->mempool);
return err;
}
- for (i = 0; i < fill / 2; i++) {
+ for (i = 0; i < geo->no_pairs / 2; i++) {
setkey(geo, new, i, bkey(geo, node, i));
setval(geo, new, i, bval(geo, node, i));
- setkey(geo, node, i, bkey(geo, node, i + fill / 2));
- setval(geo, node, i, bval(geo, node, i + fill / 2));
- clearpair(geo, node, i + fill / 2);
+ setkey(geo, node, i, bkey(geo, node, i + geo->no_pairs / 2));
+ setval(geo, node, i, bval(geo, node, i + geo->no_pairs / 2));
+ clearpair(geo, node, i + geo->no_pairs / 2);
}
- if (fill & 1) {
- setkey(geo, node, i, bkey(geo, node, fill - 1));
- setval(geo, node, i, bval(geo, node, fill - 1));
- clearpair(geo, node, fill - 1);
+ if (geo->no_pairs & 1) {
+ setkey(geo, node, i, bkey(geo, node, geo->no_pairs - 1));
+ setval(geo, node, i, bval(geo, node, geo->no_pairs - 1));
+ clearpair(geo, node, geo->no_pairs - 1);
}
goto retry;
}
- BUG_ON(fill >= geo->no_pairs);
+ BUG_ON(fill < 0);
/* shift and insert */
for (i = fill; i > pos; i--) {
--
2.7.4
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