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[PATCH] radix-tree: Remove unnecessary indirections and clean up code

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- There is frequent use of indirections in the radix code. This patch
  removes those indirections, makes the code more readable and allows
  the compilers to generate better code.

- Removing indirections allows the removal of several casts.

- Removing indirections allows the reduction of the radix_tree_path
  size from 3 to 2 words.

- Use pathp-> consistently.

- Remove unnecessary tmp variable in radix_tree_insert

- Separate the upper layer processing from the lowest layer in __lookup()
  in order to make it easier to understand what is going on and allow
  compilers to generate better code for the loop.

Signed-off-by: Christoph Lameter <clameter@sgi.com>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Cc: James Bottomley <James.Bottomley@steeleye.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
Christoph Lameter 2005-09-06 15:16:46 -07:00 • committed by Linus Torvalds
parent 987132bb0b
commit 201b6264ff
1 changed files with 82 additions and 77 deletions

159
lib/radix-tree.c
View file

@ -1,6 +1,7 @@
/* /*
* Copyright (C) 2001 Momchil Velikov * Copyright (C) 2001 Momchil Velikov
* Portions Copyright (C) 2001 Christoph Hellwig * Portions Copyright (C) 2001 Christoph Hellwig
* Copyright (C) 2005 SGI, Christoph Lameter <clameter@sgi.com>
* *
* This program is free software; you can redistribute it and/or * This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License as * modify it under the terms of the GNU General Public License as
@ -51,7 +52,7 @@ struct radix_tree_node {
}; };
struct radix_tree_path { struct radix_tree_path {
struct radix_tree_node *node, **slot; struct radix_tree_node *node;
int offset; int offset;
}; };
@ -227,7 +228,7 @@ out:
int radix_tree_insert(struct radix_tree_root *root, int radix_tree_insert(struct radix_tree_root *root,
unsigned long index, void *item) unsigned long index, void *item)
{ {
struct radix_tree_node *node = NULL, *tmp, **slot; struct radix_tree_node *node = NULL, *slot;
unsigned int height, shift; unsigned int height, shift;
int offset; int offset;
int error; int error;
@ -240,38 +241,42 @@ int radix_tree_insert(struct radix_tree_root *root,
return error; return error;
} }
slot = &root->rnode; slot = root->rnode;
height = root->height; height = root->height;
shift = (height-1) * RADIX_TREE_MAP_SHIFT; shift = (height-1) * RADIX_TREE_MAP_SHIFT;
offset = 0; /* uninitialised var warning */ offset = 0; /* uninitialised var warning */
while (height > 0) { while (height > 0) {
if (*slot == NULL) { if (slot == NULL) {
/* Have to add a child node. */ /* Have to add a child node. */
if (!(tmp = radix_tree_node_alloc(root))) if (!(slot = radix_tree_node_alloc(root)))
return -ENOMEM; return -ENOMEM;
*slot = tmp; if (node) {
if (node) node->slots[offset] = slot;
node->count++; node->count++;
} else
root->rnode = slot;
} }
/* Go a level down */ /* Go a level down */
offset = (index >> shift) & RADIX_TREE_MAP_MASK; offset = (index >> shift) & RADIX_TREE_MAP_MASK;
node = *slot; node = slot;
slot = (struct radix_tree_node **)(node->slots + offset); slot = node->slots[offset];
shift -= RADIX_TREE_MAP_SHIFT; shift -= RADIX_TREE_MAP_SHIFT;
height--; height--;
} }
if (*slot != NULL) if (slot != NULL)
return -EEXIST; return -EEXIST;
if (node) { if (node) {
node->count++; node->count++;
node->slots[offset] = item;
BUG_ON(tag_get(node, 0, offset)); BUG_ON(tag_get(node, 0, offset));
BUG_ON(tag_get(node, 1, offset)); BUG_ON(tag_get(node, 1, offset));
} } else
root->rnode = item;
*slot = item;
return 0; return 0;
} }
EXPORT_SYMBOL(radix_tree_insert); EXPORT_SYMBOL(radix_tree_insert);
@ -286,27 +291,25 @@ EXPORT_SYMBOL(radix_tree_insert);
void *radix_tree_lookup(struct radix_tree_root *root, unsigned long index) void *radix_tree_lookup(struct radix_tree_root *root, unsigned long index)
{ {
unsigned int height, shift; unsigned int height, shift;
struct radix_tree_node **slot; struct radix_tree_node *slot;
height = root->height; height = root->height;
if (index > radix_tree_maxindex(height)) if (index > radix_tree_maxindex(height))
return NULL; return NULL;
shift = (height-1) * RADIX_TREE_MAP_SHIFT; shift = (height-1) * RADIX_TREE_MAP_SHIFT;
slot = &root->rnode; slot = root->rnode;
while (height > 0) { while (height > 0) {
if (*slot == NULL) if (slot == NULL)
return NULL; return NULL;
slot = (struct radix_tree_node **) slot = slot->slots[(index >> shift) & RADIX_TREE_MAP_MASK];
((*slot)->slots +
((index >> shift) & RADIX_TREE_MAP_MASK));
shift -= RADIX_TREE_MAP_SHIFT; shift -= RADIX_TREE_MAP_SHIFT;
height--; height--;
} }
return *slot; return slot;
} }
EXPORT_SYMBOL(radix_tree_lookup); EXPORT_SYMBOL(radix_tree_lookup);
@ -326,27 +329,27 @@ void *radix_tree_tag_set(struct radix_tree_root *root,
unsigned long index, int tag) unsigned long index, int tag)
{ {
unsigned int height, shift; unsigned int height, shift;
struct radix_tree_node **slot; struct radix_tree_node *slot;
height = root->height; height = root->height;
if (index > radix_tree_maxindex(height)) if (index > radix_tree_maxindex(height))
return NULL; return NULL;
shift = (height - 1) * RADIX_TREE_MAP_SHIFT; shift = (height - 1) * RADIX_TREE_MAP_SHIFT;
slot = &root->rnode; slot = root->rnode;
while (height > 0) { while (height > 0) {
int offset; int offset;
offset = (index >> shift) & RADIX_TREE_MAP_MASK; offset = (index >> shift) & RADIX_TREE_MAP_MASK;
tag_set(*slot, tag, offset); tag_set(slot, tag, offset);
slot = (struct radix_tree_node **)((*slot)->slots + offset); slot = slot->slots[offset];
BUG_ON(*slot == NULL); BUG_ON(slot == NULL);
shift -= RADIX_TREE_MAP_SHIFT; shift -= RADIX_TREE_MAP_SHIFT;
height--; height--;
} }
return *slot; return slot;
} }
EXPORT_SYMBOL(radix_tree_tag_set); EXPORT_SYMBOL(radix_tree_tag_set);
@ -367,6 +370,7 @@ void *radix_tree_tag_clear(struct radix_tree_root *root,
unsigned long index, int tag) unsigned long index, int tag)
{ {
struct radix_tree_path path[RADIX_TREE_MAX_PATH], *pathp = path; struct radix_tree_path path[RADIX_TREE_MAX_PATH], *pathp = path;
struct radix_tree_node *slot;
unsigned int height, shift; unsigned int height, shift;
void *ret = NULL; void *ret = NULL;
@ -376,38 +380,37 @@ void *radix_tree_tag_clear(struct radix_tree_root *root,
shift = (height - 1) * RADIX_TREE_MAP_SHIFT; shift = (height - 1) * RADIX_TREE_MAP_SHIFT;
pathp->node = NULL; pathp->node = NULL;
pathp->slot = &root->rnode; slot = root->rnode;
while (height > 0) { while (height > 0) {
int offset; int offset;
if (*pathp->slot == NULL) if (slot == NULL)
goto out; goto out;
offset = (index >> shift) & RADIX_TREE_MAP_MASK; offset = (index >> shift) & RADIX_TREE_MAP_MASK;
pathp[1].offset = offset; pathp[1].offset = offset;
pathp[1].node = *pathp[0].slot; pathp[1].node = slot;
pathp[1].slot = (struct radix_tree_node **) slot = slot->slots[offset];
(pathp[1].node->slots + offset);
pathp++; pathp++;
shift -= RADIX_TREE_MAP_SHIFT; shift -= RADIX_TREE_MAP_SHIFT;
height--; height--;
} }
ret = *pathp[0].slot; ret = slot;
if (ret == NULL) if (ret == NULL)
goto out; goto out;
do { do {
int idx; int idx;
tag_clear(pathp[0].node, tag, pathp[0].offset); tag_clear(pathp->node, tag, pathp->offset);
for (idx = 0; idx < RADIX_TREE_TAG_LONGS; idx++) { for (idx = 0; idx < RADIX_TREE_TAG_LONGS; idx++) {
if (pathp[0].node->tags[tag][idx]) if (pathp->node->tags[tag][idx])
goto out; goto out;
} }
pathp--; pathp--;
} while (pathp[0].node); } while (pathp->node);
out: out:
return ret; return ret;
} }
@ -429,7 +432,7 @@ int radix_tree_tag_get(struct radix_tree_root *root,
unsigned long index, int tag) unsigned long index, int tag)
{ {
unsigned int height, shift; unsigned int height, shift;
struct radix_tree_node **slot; struct radix_tree_node *slot;
int saw_unset_tag = 0; int saw_unset_tag = 0;
height = root->height; height = root->height;
@ -437,12 +440,12 @@ int radix_tree_tag_get(struct radix_tree_root *root,
return 0; return 0;
shift = (height - 1) * RADIX_TREE_MAP_SHIFT; shift = (height - 1) * RADIX_TREE_MAP_SHIFT;
slot = &root->rnode; slot = root->rnode;
for ( ; ; ) { for ( ; ; ) {
int offset; int offset;
if (*slot == NULL) if (slot == NULL)
return 0; return 0;
offset = (index >> shift) & RADIX_TREE_MAP_MASK; offset = (index >> shift) & RADIX_TREE_MAP_MASK;
@ -451,15 +454,15 @@ int radix_tree_tag_get(struct radix_tree_root *root,
* This is just a debug check. Later, we can bale as soon as * This is just a debug check. Later, we can bale as soon as
* we see an unset tag. * we see an unset tag.
*/ */
if (!tag_get(*slot, tag, offset)) if (!tag_get(slot, tag, offset))
saw_unset_tag = 1; saw_unset_tag = 1;
if (height == 1) { if (height == 1) {
int ret = tag_get(*slot, tag, offset); int ret = tag_get(slot, tag, offset);
BUG_ON(ret && saw_unset_tag); BUG_ON(ret && saw_unset_tag);
return ret; return ret;
} }
slot = (struct radix_tree_node **)((*slot)->slots + offset); slot = slot->slots[offset];
shift -= RADIX_TREE_MAP_SHIFT; shift -= RADIX_TREE_MAP_SHIFT;
height--; height--;
} }
@ -472,17 +475,21 @@ __lookup(struct radix_tree_root *root, void **results, unsigned long index,
unsigned int max_items, unsigned long *next_index) unsigned int max_items, unsigned long *next_index)
{ {
unsigned int nr_found = 0; unsigned int nr_found = 0;
unsigned int shift; unsigned int shift, height;
unsigned int height = root->height;
struct radix_tree_node *slot; struct radix_tree_node *slot;
unsigned long i;
height = root->height;
if (height == 0)
goto out;
shift = (height-1) * RADIX_TREE_MAP_SHIFT; shift = (height-1) * RADIX_TREE_MAP_SHIFT;
slot = root->rnode; slot = root->rnode;
while (height > 0) { for ( ; height > 1; height--) {
unsigned long i = (index >> shift) & RADIX_TREE_MAP_MASK;
for ( ; i < RADIX_TREE_MAP_SIZE; i++) { for (i = (index >> shift) & RADIX_TREE_MAP_MASK ;
i < RADIX_TREE_MAP_SIZE; i++) {
if (slot->slots[i] != NULL) if (slot->slots[i] != NULL)
break; break;
index &= ~((1UL << shift) - 1); index &= ~((1UL << shift) - 1);
@ -492,22 +499,20 @@ __lookup(struct radix_tree_root *root, void **results, unsigned long index,
} }
if (i == RADIX_TREE_MAP_SIZE) if (i == RADIX_TREE_MAP_SIZE)
goto out; goto out;
height--;
if (height == 0) { /* Bottom level: grab some items */
unsigned long j = index & RADIX_TREE_MAP_MASK;
for ( ; j < RADIX_TREE_MAP_SIZE; j++) {
index++;
if (slot->slots[j]) {
results[nr_found++] = slot->slots[j];
if (nr_found == max_items)
goto out;
}
}
}
shift -= RADIX_TREE_MAP_SHIFT; shift -= RADIX_TREE_MAP_SHIFT;
slot = slot->slots[i]; slot = slot->slots[i];
} }
/* Bottom level: grab some items */
for (i = index & RADIX_TREE_MAP_MASK; i < RADIX_TREE_MAP_SIZE; i++) {
index++;
if (slot->slots[i]) {
results[nr_found++] = slot->slots[i];
if (nr_found == max_items)
goto out;
}
}
out: out:
*next_index = index; *next_index = index;
return nr_found; return nr_found;
@ -655,6 +660,7 @@ void *radix_tree_delete(struct radix_tree_root *root, unsigned long index)
{ {
struct radix_tree_path path[RADIX_TREE_MAX_PATH], *pathp = path; struct radix_tree_path path[RADIX_TREE_MAX_PATH], *pathp = path;
struct radix_tree_path *orig_pathp; struct radix_tree_path *orig_pathp;
struct radix_tree_node *slot;
unsigned int height, shift; unsigned int height, shift;
void *ret = NULL; void *ret = NULL;
char tags[RADIX_TREE_TAGS]; char tags[RADIX_TREE_TAGS];
@ -666,25 +672,23 @@ void *radix_tree_delete(struct radix_tree_root *root, unsigned long index)
shift = (height - 1) * RADIX_TREE_MAP_SHIFT; shift = (height - 1) * RADIX_TREE_MAP_SHIFT;
pathp->node = NULL; pathp->node = NULL;
pathp->slot = &root->rnode; slot = root->rnode;
while (height > 0) { for ( ; height > 0; height--) {
int offset; int offset;
if (*pathp->slot == NULL) if (slot == NULL)
goto out; goto out;
offset = (index >> shift) & RADIX_TREE_MAP_MASK; offset = (index >> shift) & RADIX_TREE_MAP_MASK;
pathp[1].offset = offset; pathp[1].offset = offset;
pathp[1].node = *pathp[0].slot; pathp[1].node = slot;
pathp[1].slot = (struct radix_tree_node **) slot = slot->slots[offset];
(pathp[1].node->slots + offset);
pathp++; pathp++;
shift -= RADIX_TREE_MAP_SHIFT; shift -= RADIX_TREE_MAP_SHIFT;
height--;
} }
ret = *pathp[0].slot; ret = slot;
if (ret == NULL) if (ret == NULL)
goto out; goto out;
@ -704,10 +708,10 @@ void *radix_tree_delete(struct radix_tree_root *root, unsigned long index)
if (tags[tag]) if (tags[tag])
continue; continue;
tag_clear(pathp[0].node, tag, pathp[0].offset); tag_clear(pathp->node, tag, pathp->offset);
for (idx = 0; idx < RADIX_TREE_TAG_LONGS; idx++) { for (idx = 0; idx < RADIX_TREE_TAG_LONGS; idx++) {
if (pathp[0].node->tags[tag][idx]) { if (pathp->node->tags[tag][idx]) {
tags[tag] = 1; tags[tag] = 1;
nr_cleared_tags--; nr_cleared_tags--;
break; break;
@ -715,18 +719,19 @@ void *radix_tree_delete(struct radix_tree_root *root, unsigned long index)
} }
} }
pathp--; pathp--;
} while (pathp[0].node && nr_cleared_tags); } while (pathp->node && nr_cleared_tags);
pathp = orig_pathp; /* Now free the nodes we do not need anymore */
*pathp[0].slot = NULL; for (pathp = orig_pathp; pathp->node; pathp--) {
while (pathp[0].node && --pathp[0].node->count == 0) { pathp->node->slots[pathp->offset] = NULL;
pathp--; if (--pathp->node->count)
BUG_ON(*pathp[0].slot == NULL); goto out;
*pathp[0].slot = NULL;
radix_tree_node_free(pathp[1].node); /* Node with zero slots in use so free it */
radix_tree_node_free(pathp->node);
} }
if (root->rnode == NULL) root->rnode = NULL;
root->height = 0; root->height = 0;
out: out:
return ret; return ret;
} }