[PATCH] radix-tree: direct data
The ability to have height 0 radix trees (a direct pointer to the data item rather than going through a full node->slot) quietly disappeared with old-2.6-bkcvs commit ffee171812d51652f9ba284302d9e5c5cc14bdfd. On 64-bit machines this causes nearly 600 bytes to be used for every <= 4K file in pagecache. Re-introduce this feature, root tags stored in spare ->gfp_mask bits. Simplify radix_tree_delete's complex tag clearing arrangement (which would become even more complex) by just falling back to tag clearing functions (the pagecache radix-tree never uses this path anyway, so the icache savings will mean it's actually a speedup). On my 4GB G5, this saves 8MB RAM per kernel kernel source+object tree in pagecache. Pagecache lookup, insertion, and removal speed for small files will also be improved. This makes RCU radix tree harder, but it's worth it. Signed-off-by: Nick Piggin <npiggin@suse.de> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
Nick Piggin
Linus Torvalds
parent
929f97276b
commit
612d6c19db
2 changed files with 114 additions and 83 deletions
|
|
@ -23,6 +23,9 @@
|
|||
#include <linux/preempt.h>
|
||||
#include <linux/types.h>
|
||||
|
||||
#define RADIX_TREE_MAX_TAGS 2
|
||||
|
||||
/* root tags are stored in gfp_mask, shifted by __GFP_BITS_SHIFT */
|
||||
struct radix_tree_root {
|
||||
unsigned int height;
|
||||
gfp_t gfp_mask;
|
||||
|
|
@ -45,8 +48,6 @@ do { \
|
|||
(root)->rnode = NULL; \
|
||||
} while (0)
|
||||
|
||||
#define RADIX_TREE_MAX_TAGS 2
|
||||
|
||||
int radix_tree_insert(struct radix_tree_root *, unsigned long, void *);
|
||||
void *radix_tree_lookup(struct radix_tree_root *, unsigned long);
|
||||
void **radix_tree_lookup_slot(struct radix_tree_root *, unsigned long);
|
||||
|
|
|
|||
192
lib/radix-tree.c
192
lib/radix-tree.c
|
|
@ -74,6 +74,11 @@ struct radix_tree_preload {
|
|||
};
|
||||
DEFINE_PER_CPU(struct radix_tree_preload, radix_tree_preloads) = { 0, };
|
||||
|
||||
static inline gfp_t root_gfp_mask(struct radix_tree_root *root)
|
||||
{
|
||||
return root->gfp_mask & __GFP_BITS_MASK;
|
||||
}
|
||||
|
||||
/*
|
||||
* This assumes that the caller has performed appropriate preallocation, and
|
||||
* that the caller has pinned this thread of control to the current CPU.
|
||||
|
|
@ -82,9 +87,10 @@ static struct radix_tree_node *
|
|||
radix_tree_node_alloc(struct radix_tree_root *root)
|
||||
{
|
||||
struct radix_tree_node *ret;
|
||||
gfp_t gfp_mask = root_gfp_mask(root);
|
||||
|
||||
ret = kmem_cache_alloc(radix_tree_node_cachep, root->gfp_mask);
|
||||
if (ret == NULL && !(root->gfp_mask & __GFP_WAIT)) {
|
||||
ret = kmem_cache_alloc(radix_tree_node_cachep, gfp_mask);
|
||||
if (ret == NULL && !(gfp_mask & __GFP_WAIT)) {
|
||||
struct radix_tree_preload *rtp;
|
||||
|
||||
rtp = &__get_cpu_var(radix_tree_preloads);
|
||||
|
|
@ -152,6 +158,27 @@ static inline int tag_get(struct radix_tree_node *node, unsigned int tag,
|
|||
return test_bit(offset, node->tags[tag]);
|
||||
}
|
||||
|
||||
static inline void root_tag_set(struct radix_tree_root *root, unsigned int tag)
|
||||
{
|
||||
root->gfp_mask |= (1 << (tag + __GFP_BITS_SHIFT));
|
||||
}
|
||||
|
||||
|
||||
static inline void root_tag_clear(struct radix_tree_root *root, unsigned int tag)
|
||||
{
|
||||
root->gfp_mask &= ~(1 << (tag + __GFP_BITS_SHIFT));
|
||||
}
|
||||
|
||||
static inline void root_tag_clear_all(struct radix_tree_root *root)
|
||||
{
|
||||
root->gfp_mask &= __GFP_BITS_MASK;
|
||||
}
|
||||
|
||||
static inline int root_tag_get(struct radix_tree_root *root, unsigned int tag)
|
||||
{
|
||||
return root->gfp_mask & (1 << (tag + __GFP_BITS_SHIFT));
|
||||
}
|
||||
|
||||
/*
|
||||
* Returns 1 if any slot in the node has this tag set.
|
||||
* Otherwise returns 0.
|
||||
|
|
@ -182,7 +209,6 @@ static int radix_tree_extend(struct radix_tree_root *root, unsigned long index)
|
|||
{
|
||||
struct radix_tree_node *node;
|
||||
unsigned int height;
|
||||
char tags[RADIX_TREE_MAX_TAGS];
|
||||
int tag;
|
||||
|
||||
/* Figure out what the height should be. */
|
||||
|
|
@ -195,16 +221,6 @@ static int radix_tree_extend(struct radix_tree_root *root, unsigned long index)
|
|||
goto out;
|
||||
}
|
||||
|
||||
/*
|
||||
* Prepare the tag status of the top-level node for propagation
|
||||
* into the newly-pushed top-level node(s)
|
||||
*/
|
||||
for (tag = 0; tag < RADIX_TREE_MAX_TAGS; tag++) {
|
||||
tags[tag] = 0;
|
||||
if (any_tag_set(root->rnode, tag))
|
||||
tags[tag] = 1;
|
||||
}
|
||||
|
||||
do {
|
||||
if (!(node = radix_tree_node_alloc(root)))
|
||||
return -ENOMEM;
|
||||
|
|
@ -214,7 +230,7 @@ static int radix_tree_extend(struct radix_tree_root *root, unsigned long index)
|
|||
|
||||
/* Propagate the aggregated tag info into the new root */
|
||||
for (tag = 0; tag < RADIX_TREE_MAX_TAGS; tag++) {
|
||||
if (tags[tag])
|
||||
if (root_tag_get(root, tag))
|
||||
tag_set(node, tag, 0);
|
||||
}
|
||||
|
||||
|
|
@ -243,8 +259,7 @@ int radix_tree_insert(struct radix_tree_root *root,
|
|||
int error;
|
||||
|
||||
/* Make sure the tree is high enough. */
|
||||
if ((!index && !root->rnode) ||
|
||||
index > radix_tree_maxindex(root->height)) {
|
||||
if (index > radix_tree_maxindex(root->height)) {
|
||||
error = radix_tree_extend(root, index);
|
||||
if (error)
|
||||
return error;
|
||||
|
|
@ -255,7 +270,7 @@ int radix_tree_insert(struct radix_tree_root *root,
|
|||
shift = (height-1) * RADIX_TREE_MAP_SHIFT;
|
||||
|
||||
offset = 0; /* uninitialised var warning */
|
||||
do {
|
||||
while (height > 0) {
|
||||
if (slot == NULL) {
|
||||
/* Have to add a child node. */
|
||||
if (!(slot = radix_tree_node_alloc(root)))
|
||||
|
|
@ -273,16 +288,21 @@ int radix_tree_insert(struct radix_tree_root *root,
|
|||
slot = node->slots[offset];
|
||||
shift -= RADIX_TREE_MAP_SHIFT;
|
||||
height--;
|
||||
} while (height > 0);
|
||||
}
|
||||
|
||||
if (slot != NULL)
|
||||
return -EEXIST;
|
||||
|
||||
BUG_ON(!node);
|
||||
node->count++;
|
||||
node->slots[offset] = item;
|
||||
BUG_ON(tag_get(node, 0, offset));
|
||||
BUG_ON(tag_get(node, 1, offset));
|
||||
if (node) {
|
||||
node->count++;
|
||||
node->slots[offset] = item;
|
||||
BUG_ON(tag_get(node, 0, offset));
|
||||
BUG_ON(tag_get(node, 1, offset));
|
||||
} else {
|
||||
root->rnode = item;
|
||||
BUG_ON(root_tag_get(root, 0));
|
||||
BUG_ON(root_tag_get(root, 1));
|
||||
}
|
||||
|
||||
return 0;
|
||||
}
|
||||
|
|
@ -295,9 +315,13 @@ static inline void **__lookup_slot(struct radix_tree_root *root,
|
|||
struct radix_tree_node **slot;
|
||||
|
||||
height = root->height;
|
||||
|
||||
if (index > radix_tree_maxindex(height))
|
||||
return NULL;
|
||||
|
||||
if (height == 0 && root->rnode)
|
||||
return (void **)&root->rnode;
|
||||
|
||||
shift = (height-1) * RADIX_TREE_MAP_SHIFT;
|
||||
slot = &root->rnode;
|
||||
|
||||
|
|
@ -368,8 +392,8 @@ void *radix_tree_tag_set(struct radix_tree_root *root,
|
|||
if (index > radix_tree_maxindex(height))
|
||||
return NULL;
|
||||
|
||||
shift = (height - 1) * RADIX_TREE_MAP_SHIFT;
|
||||
slot = root->rnode;
|
||||
shift = (height - 1) * RADIX_TREE_MAP_SHIFT;
|
||||
|
||||
while (height > 0) {
|
||||
int offset;
|
||||
|
|
@ -383,6 +407,10 @@ void *radix_tree_tag_set(struct radix_tree_root *root,
|
|||
height--;
|
||||
}
|
||||
|
||||
/* set the root's tag bit */
|
||||
if (slot && !root_tag_get(root, tag))
|
||||
root_tag_set(root, tag);
|
||||
|
||||
return slot;
|
||||
}
|
||||
EXPORT_SYMBOL(radix_tree_tag_set);
|
||||
|
|
@ -405,9 +433,8 @@ void *radix_tree_tag_clear(struct radix_tree_root *root,
|
|||
unsigned long index, unsigned int tag)
|
||||
{
|
||||
struct radix_tree_path path[RADIX_TREE_MAX_PATH], *pathp = path;
|
||||
struct radix_tree_node *slot;
|
||||
struct radix_tree_node *slot = NULL;
|
||||
unsigned int height, shift;
|
||||
void *ret = NULL;
|
||||
|
||||
height = root->height;
|
||||
if (index > radix_tree_maxindex(height))
|
||||
|
|
@ -432,20 +459,24 @@ void *radix_tree_tag_clear(struct radix_tree_root *root,
|
|||
height--;
|
||||
}
|
||||
|
||||
ret = slot;
|
||||
if (ret == NULL)
|
||||
if (slot == NULL)
|
||||
goto out;
|
||||
|
||||
do {
|
||||
while (pathp->node) {
|
||||
if (!tag_get(pathp->node, tag, pathp->offset))
|
||||
goto out;
|
||||
tag_clear(pathp->node, tag, pathp->offset);
|
||||
if (any_tag_set(pathp->node, tag))
|
||||
goto out;
|
||||
pathp--;
|
||||
} while (pathp->node);
|
||||
}
|
||||
|
||||
/* clear the root's tag bit */
|
||||
if (root_tag_get(root, tag))
|
||||
root_tag_clear(root, tag);
|
||||
|
||||
out:
|
||||
return ret;
|
||||
return slot;
|
||||
}
|
||||
EXPORT_SYMBOL(radix_tree_tag_clear);
|
||||
|
||||
|
|
@ -458,9 +489,8 @@ EXPORT_SYMBOL(radix_tree_tag_clear);
|
|||
*
|
||||
* Return values:
|
||||
*
|
||||
* 0: tag not present
|
||||
* 1: tag present, set
|
||||
* -1: tag present, unset
|
||||
* 0: tag not present or not set
|
||||
* 1: tag set
|
||||
*/
|
||||
int radix_tree_tag_get(struct radix_tree_root *root,
|
||||
unsigned long index, unsigned int tag)
|
||||
|
|
@ -473,6 +503,13 @@ int radix_tree_tag_get(struct radix_tree_root *root,
|
|||
if (index > radix_tree_maxindex(height))
|
||||
return 0;
|
||||
|
||||
/* check the root's tag bit */
|
||||
if (!root_tag_get(root, tag))
|
||||
return 0;
|
||||
|
||||
if (height == 0)
|
||||
return 1;
|
||||
|
||||
shift = (height - 1) * RADIX_TREE_MAP_SHIFT;
|
||||
slot = root->rnode;
|
||||
|
||||
|
|
@ -494,7 +531,7 @@ int radix_tree_tag_get(struct radix_tree_root *root,
|
|||
int ret = tag_get(slot, tag, offset);
|
||||
|
||||
BUG_ON(ret && saw_unset_tag);
|
||||
return ret ? 1 : -1;
|
||||
return ret;
|
||||
}
|
||||
slot = slot->slots[offset];
|
||||
shift -= RADIX_TREE_MAP_SHIFT;
|
||||
|
|
@ -514,8 +551,11 @@ __lookup(struct radix_tree_root *root, void **results, unsigned long index,
|
|||
unsigned long i;
|
||||
|
||||
height = root->height;
|
||||
if (height == 0)
|
||||
if (height == 0) {
|
||||
if (root->rnode && index == 0)
|
||||
results[nr_found++] = root->rnode;
|
||||
goto out;
|
||||
}
|
||||
|
||||
shift = (height-1) * RADIX_TREE_MAP_SHIFT;
|
||||
slot = root->rnode;
|
||||
|
|
@ -603,10 +643,16 @@ __lookup_tag(struct radix_tree_root *root, void **results, unsigned long index,
|
|||
unsigned int height = root->height;
|
||||
struct radix_tree_node *slot;
|
||||
|
||||
if (height == 0) {
|
||||
if (root->rnode && index == 0)
|
||||
results[nr_found++] = root->rnode;
|
||||
goto out;
|
||||
}
|
||||
|
||||
shift = (height - 1) * RADIX_TREE_MAP_SHIFT;
|
||||
slot = root->rnode;
|
||||
|
||||
while (height > 0) {
|
||||
do {
|
||||
unsigned long i = (index >> shift) & RADIX_TREE_MAP_MASK;
|
||||
|
||||
for ( ; i < RADIX_TREE_MAP_SIZE; i++) {
|
||||
|
|
@ -637,7 +683,7 @@ __lookup_tag(struct radix_tree_root *root, void **results, unsigned long index,
|
|||
}
|
||||
shift -= RADIX_TREE_MAP_SHIFT;
|
||||
slot = slot->slots[i];
|
||||
}
|
||||
} while (height > 0);
|
||||
out:
|
||||
*next_index = index;
|
||||
return nr_found;
|
||||
|
|
@ -665,6 +711,10 @@ radix_tree_gang_lookup_tag(struct radix_tree_root *root, void **results,
|
|||
unsigned long cur_index = first_index;
|
||||
unsigned int ret = 0;
|
||||
|
||||
/* check the root's tag bit */
|
||||
if (!root_tag_get(root, tag))
|
||||
return 0;
|
||||
|
||||
while (ret < max_items) {
|
||||
unsigned int nr_found;
|
||||
unsigned long next_index; /* Index of next search */
|
||||
|
|
@ -689,7 +739,7 @@ EXPORT_SYMBOL(radix_tree_gang_lookup_tag);
|
|||
static inline void radix_tree_shrink(struct radix_tree_root *root)
|
||||
{
|
||||
/* try to shrink tree height */
|
||||
while (root->height > 1 &&
|
||||
while (root->height > 0 &&
|
||||
root->rnode->count == 1 &&
|
||||
root->rnode->slots[0]) {
|
||||
struct radix_tree_node *to_free = root->rnode;
|
||||
|
|
@ -717,12 +767,8 @@ static inline void radix_tree_shrink(struct radix_tree_root *root)
|
|||
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 *orig_pathp;
|
||||
struct radix_tree_node *slot;
|
||||
struct radix_tree_node *slot = NULL;
|
||||
unsigned int height, shift;
|
||||
void *ret = NULL;
|
||||
char tags[RADIX_TREE_MAX_TAGS];
|
||||
int nr_cleared_tags;
|
||||
int tag;
|
||||
int offset;
|
||||
|
||||
|
|
@ -730,11 +776,17 @@ void *radix_tree_delete(struct radix_tree_root *root, unsigned long index)
|
|||
if (index > radix_tree_maxindex(height))
|
||||
goto out;
|
||||
|
||||
slot = root->rnode;
|
||||
if (height == 0 && root->rnode) {
|
||||
root_tag_clear_all(root);
|
||||
root->rnode = NULL;
|
||||
goto out;
|
||||
}
|
||||
|
||||
shift = (height - 1) * RADIX_TREE_MAP_SHIFT;
|
||||
pathp->node = NULL;
|
||||
slot = root->rnode;
|
||||
|
||||
for ( ; height > 0; height--) {
|
||||
do {
|
||||
if (slot == NULL)
|
||||
goto out;
|
||||
|
||||
|
|
@ -744,44 +796,22 @@ void *radix_tree_delete(struct radix_tree_root *root, unsigned long index)
|
|||
pathp->node = slot;
|
||||
slot = slot->slots[offset];
|
||||
shift -= RADIX_TREE_MAP_SHIFT;
|
||||
}
|
||||
height--;
|
||||
} while (height > 0);
|
||||
|
||||
ret = slot;
|
||||
if (ret == NULL)
|
||||
if (slot == NULL)
|
||||
goto out;
|
||||
|
||||
orig_pathp = pathp;
|
||||
|
||||
/*
|
||||
* Clear all tags associated with the just-deleted item
|
||||
*/
|
||||
nr_cleared_tags = 0;
|
||||
for (tag = 0; tag < RADIX_TREE_MAX_TAGS; tag++) {
|
||||
tags[tag] = 1;
|
||||
if (tag_get(pathp->node, tag, pathp->offset)) {
|
||||
tag_clear(pathp->node, tag, pathp->offset);
|
||||
if (!any_tag_set(pathp->node, tag)) {
|
||||
tags[tag] = 0;
|
||||
nr_cleared_tags++;
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
for (pathp--; nr_cleared_tags && pathp->node; pathp--) {
|
||||
for (tag = 0; tag < RADIX_TREE_MAX_TAGS; tag++) {
|
||||
if (tags[tag])
|
||||
continue;
|
||||
|
||||
tag_clear(pathp->node, tag, pathp->offset);
|
||||
if (any_tag_set(pathp->node, tag)) {
|
||||
tags[tag] = 1;
|
||||
nr_cleared_tags--;
|
||||
}
|
||||
}
|
||||
if (tag_get(pathp->node, tag, pathp->offset))
|
||||
radix_tree_tag_clear(root, index, tag);
|
||||
}
|
||||
|
||||
/* Now free the nodes we do not need anymore */
|
||||
for (pathp = orig_pathp; pathp->node; pathp--) {
|
||||
while (pathp->node) {
|
||||
pathp->node->slots[pathp->offset] = NULL;
|
||||
pathp->node->count--;
|
||||
|
||||
|
|
@ -793,11 +823,15 @@ void *radix_tree_delete(struct radix_tree_root *root, unsigned long index)
|
|||
|
||||
/* Node with zero slots in use so free it */
|
||||
radix_tree_node_free(pathp->node);
|
||||
|
||||
pathp--;
|
||||
}
|
||||
root->rnode = NULL;
|
||||
root_tag_clear_all(root);
|
||||
root->height = 0;
|
||||
root->rnode = NULL;
|
||||
|
||||
out:
|
||||
return ret;
|
||||
return slot;
|
||||
}
|
||||
EXPORT_SYMBOL(radix_tree_delete);
|
||||
|
||||
|
|
@ -808,11 +842,7 @@ EXPORT_SYMBOL(radix_tree_delete);
|
|||
*/
|
||||
int radix_tree_tagged(struct radix_tree_root *root, unsigned int tag)
|
||||
{
|
||||
struct radix_tree_node *rnode;
|
||||
rnode = root->rnode;
|
||||
if (!rnode)
|
||||
return 0;
|
||||
return any_tag_set(rnode, tag);
|
||||
return root_tag_get(root, tag);
|
||||
}
|
||||
EXPORT_SYMBOL(radix_tree_tagged);
|
||||
|
||||
|
|
|
|||
Loading…
Reference in a new issue