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Old 07-25-2011, 09:57 PM
Mikulas Patocka
 
Default sysfs: use rb-tree for inode number lookup

On Thu, 21 Jul 2011, Mikulas Patocka wrote:

> sysfs: use rb-tree for inode number lookup
>
> This patch makes sysfs use red-black tree for inode number lookup.
> Together with a previous patch to use red-black tree for name lookup,
> this patch makes all sysfs lookups to have O(log n) complexity.
>
> This patch improves time to create 10000 block devices from 68 seconds to
> 37 seconds. It improves time to delete 10000 block devices from 11 seconds
> to 3.3 seconds.
>
> Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
>
> ---
> fs/sysfs/dir.c | 89 ++++++++++++++++++++++++++++++-------------------------
> fs/sysfs/sysfs.h | 5 +--
> 2 files changed, 52 insertions(+), 42 deletions(-)
>
> Index: linux-3.0-rc7-fast/fs/sysfs/dir.c
> ================================================== =================
> --- linux-3.0-rc7-fast.orig/fs/sysfs/dir.c 2011-07-20 20:55:15.000000000 +0200
> +++ linux-3.0-rc7-fast/fs/sysfs/dir.c 2011-07-20 23:30:47.000000000 +0200
> @@ -43,26 +43,30 @@ static DEFINE_IDA(sysfs_ino_ida);
> static void sysfs_link_sibling(struct sysfs_dirent *sd)
> {
> struct sysfs_dirent *parent_sd = sd->s_parent;
> - struct sysfs_dirent **pos;
>
> struct rb_node **p;
> struct rb_node *parent;
>
> - BUG_ON(sd->s_sibling);
> -
> if (sysfs_type(sd) == SYSFS_DIR)
> parent_sd->s_dir.subdirs++;
>
> - /* Store directory entries in order by ino. This allows
> - * readdir to properly restart without having to add a
> - * cursor into the s_dir.children list.
> - */
> - for (pos = &parent_sd->s_dir.children; *pos; pos = &(*pos)->s_sibling) {
> - if (sd->s_ino < (*pos)->s_ino)
> - break;
> + p = &parent_sd->s_dir.inode_tree.rb_node;
> + parent = NULL;
> + while (*p) {
> + parent = *p;
> +#define node rb_entry(parent, struct sysfs_dirent, inode_node)
> + if (sd->s_ino < node->s_ino) {
> + p = &node->inode_node.rb_left;
> + } else if (sd->s_ino > node->s_ino) {
> + p = &node->inode_node.rb_right;
> + } else {
> + printk(KERN_CRIT "sysfs: inserting duplicate inode '%lx'
", sd->s_ino);
> + BUG();
> + }
> +#undef node
> }
> - sd->s_sibling = *pos;
> - *pos = sd;
> + rb_link_node(&sd->inode_node, parent, p);
> + rb_insert_color(&sd->inode_node, &parent_sd->s_dir.inode_tree);
>
> p = &parent_sd->s_dir.name_tree.rb_node;
> parent = NULL;
> @@ -97,20 +101,10 @@ static void sysfs_link_sibling(struct sy
> */
> static void sysfs_unlink_sibling(struct sysfs_dirent *sd)
> {
> - struct sysfs_dirent **pos;
> -
> if (sysfs_type(sd) == SYSFS_DIR)
> sd->s_parent->s_dir.subdirs--;
>
> - for (pos = &sd->s_parent->s_dir.children; *pos;
> - pos = &(*pos)->s_sibling) {
> - if (*pos == sd) {
> - *pos = sd->s_sibling;
> - sd->s_sibling = NULL;
> - break;
> - }
> - }
> -
> + rb_erase(&sd->inode_node, &sd->s_parent->s_dir.inode_tree);
> rb_erase(&sd->name_node, &sd->s_parent->s_dir.name_tree);
> }
>
> @@ -778,21 +772,19 @@ void sysfs_remove_subdir(struct sysfs_di
> static void __sysfs_remove_dir(struct sysfs_dirent *dir_sd)
> {
> struct sysfs_addrm_cxt acxt;
> - struct sysfs_dirent **pos;
> + struct rb_node *pos;
>
> if (!dir_sd)
> return;
>
> pr_debug("sysfs %s: removing dir
", dir_sd->s_name);
> sysfs_addrm_start(&acxt, dir_sd);
> - pos = &dir_sd->s_dir.children;
> - while (*pos) {
> - struct sysfs_dirent *sd = *pos;
> -
> + pos = rb_first(&dir_sd->s_dir.inode_tree);
> + while (pos) {
> + struct sysfs_dirent *sd = rb_entry(pos, struct sysfs_dirent, inode_node);
> + pos = rb_next(pos);
> if (sysfs_type(sd) != SYSFS_DIR)
> sysfs_remove_one(&acxt, sd);
> - else
> - pos = &(*pos)->s_sibling;
> }
> sysfs_addrm_finish(&acxt);
>
> @@ -915,12 +907,28 @@ static struct sysfs_dirent *sysfs_dir_po
> pos = NULL;
> }
> if (!pos && (ino > 1) && (ino < INT_MAX)) {
> - pos = parent_sd->s_dir.children;
> - while (pos && (ino > pos->s_ino))
> - pos = pos->s_sibling;
> + struct rb_node *p = parent_sd->s_dir.inode_tree.rb_node;
> + while (p) {
> +#define node rb_entry(p, struct sysfs_dirent, inode_node)
> + if (ino < node->s_ino) {
> + pos = node;
> + p = node->inode_node.rb_left;
> + } else if (node->s_ino > ino) {
> + p = node->inode_node.rb_right;
> + } else {
> + pos = node;
> + break;
> + }
> +#undef node
> + }
> + }
> + while (pos && pos->s_ns && pos->s_ns != ns) {
> + struct rb_node *p = rb_next(&pos->inode_node);
> + if (!p)
> + pos = NULL;
> + else
> + pos = rb_entry(p, struct sysfs_dirent, inode_node);
> }
> - while (pos && pos->s_ns && pos->s_ns != ns)
> - pos = pos->s_sibling;
> return pos;
> }
>
> @@ -928,10 +936,13 @@ static struct sysfs_dirent *sysfs_dir_ne
> struct sysfs_dirent *parent_sd, ino_t ino, struct sysfs_dirent *pos)
> {
> pos = sysfs_dir_pos(ns, parent_sd, ino, pos);
> - if (pos)
> - pos = pos->s_sibling;
> - while (pos && pos->s_ns && pos->s_ns != ns)
> - pos = pos->s_sibling;
> + if (pos) do {
> + struct rb_node *p = rb_next(&pos->inode_node);
> + if (!p)
> + pos = NULL;
> + else
> + pos = rb_entry(p, struct sysfs_dirent, inode_node);
> + } while (pos && pos->s_ns && pos->s_ns != ns);
> return pos;
> }
>
> Index: linux-3.0-rc7-fast/fs/sysfs/sysfs.h
> ================================================== =================
> --- linux-3.0-rc7-fast.orig/fs/sysfs/sysfs.h 2011-07-20 20:46:50.000000000 +0200
> +++ linux-3.0-rc7-fast/fs/sysfs/sysfs.h 2011-07-20 21:00:28.000000000 +0200
> @@ -18,11 +18,10 @@ struct sysfs_open_dirent;
> /* type-specific structures for sysfs_dirent->s_* union members */
> struct sysfs_elem_dir {
> struct kobject *kobj;
> - /* children list starts here and goes through sd->s_sibling */
> - struct sysfs_dirent *children;
>
> unsigned long subdirs;
>
> + struct rb_root inode_tree;
> struct rb_root name_tree;
> };
>
> @@ -61,9 +60,9 @@ struct sysfs_dirent {
> struct lockdep_map dep_map;
> #endif
> struct sysfs_dirent *s_parent;
> - struct sysfs_dirent *s_sibling;
> const char *s_name;
>
> + struct rb_node inode_node;
> struct rb_node name_node;
>
> union {
>
>

Hi

This is updated patch. It fixes a typo in the rbtree search.

Mikulas

---

sysfs: use rb-tree for inode number lookup

This patch makes sysfs use red-black tree for inode number lookup.
Together with a previous patch to use red-black tree for name lookup,
this patch makes all sysfs lookups to have O(log n) complexity.

Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>

---
fs/sysfs/dir.c | 89 ++++++++++++++++++++++++++++++-------------------------
fs/sysfs/sysfs.h | 5 +--
2 files changed, 52 insertions(+), 42 deletions(-)

Index: linux-3.0-fast/fs/sysfs/dir.c
================================================== =================
--- linux-3.0-fast.orig/fs/sysfs/dir.c 2011-07-25 23:41:10.000000000 +0200
+++ linux-3.0-fast/fs/sysfs/dir.c 2011-07-25 23:41:13.000000000 +0200
@@ -43,26 +43,30 @@ static DEFINE_IDA(sysfs_ino_ida);
static void sysfs_link_sibling(struct sysfs_dirent *sd)
{
struct sysfs_dirent *parent_sd = sd->s_parent;
- struct sysfs_dirent **pos;

struct rb_node **p;
struct rb_node *parent;

- BUG_ON(sd->s_sibling);
-
if (sysfs_type(sd) == SYSFS_DIR)
parent_sd->s_dir.subdirs++;

- /* Store directory entries in order by ino. This allows
- * readdir to properly restart without having to add a
- * cursor into the s_dir.children list.
- */
- for (pos = &parent_sd->s_dir.children; *pos; pos = &(*pos)->s_sibling) {
- if (sd->s_ino < (*pos)->s_ino)
- break;
+ p = &parent_sd->s_dir.inode_tree.rb_node;
+ parent = NULL;
+ while (*p) {
+ parent = *p;
+#define node rb_entry(parent, struct sysfs_dirent, inode_node)
+ if (sd->s_ino < node->s_ino) {
+ p = &node->inode_node.rb_left;
+ } else if (sd->s_ino > node->s_ino) {
+ p = &node->inode_node.rb_right;
+ } else {
+ printk(KERN_CRIT "sysfs: inserting duplicate inode '%lx'
", sd->s_ino);
+ BUG();
+ }
+#undef node
}
- sd->s_sibling = *pos;
- *pos = sd;
+ rb_link_node(&sd->inode_node, parent, p);
+ rb_insert_color(&sd->inode_node, &parent_sd->s_dir.inode_tree);

p = &parent_sd->s_dir.name_tree.rb_node;
parent = NULL;
@@ -94,20 +98,10 @@ static void sysfs_link_sibling(struct sy
*/
static void sysfs_unlink_sibling(struct sysfs_dirent *sd)
{
- struct sysfs_dirent **pos;
-
if (sysfs_type(sd) == SYSFS_DIR)
sd->s_parent->s_dir.subdirs--;

- for (pos = &sd->s_parent->s_dir.children; *pos;
- pos = &(*pos)->s_sibling) {
- if (*pos == sd) {
- *pos = sd->s_sibling;
- sd->s_sibling = NULL;
- break;
- }
- }
-
+ rb_erase(&sd->inode_node, &sd->s_parent->s_dir.inode_tree);
rb_erase(&sd->name_node, &sd->s_parent->s_dir.name_tree);
}

@@ -788,21 +782,19 @@ void sysfs_remove_subdir(struct sysfs_di
static void __sysfs_remove_dir(struct sysfs_dirent *dir_sd)
{
struct sysfs_addrm_cxt acxt;
- struct sysfs_dirent **pos;
+ struct rb_node *pos;

if (!dir_sd)
return;

pr_debug("sysfs %s: removing dir
", dir_sd->s_name);
sysfs_addrm_start(&acxt, dir_sd);
- pos = &dir_sd->s_dir.children;
- while (*pos) {
- struct sysfs_dirent *sd = *pos;
-
+ pos = rb_first(&dir_sd->s_dir.inode_tree);
+ while (pos) {
+ struct sysfs_dirent *sd = rb_entry(pos, struct sysfs_dirent, inode_node);
+ pos = rb_next(pos);
if (sysfs_type(sd) != SYSFS_DIR)
sysfs_remove_one(&acxt, sd);
- else
- pos = &(*pos)->s_sibling;
}
sysfs_addrm_finish(&acxt);

@@ -925,12 +917,28 @@ static struct sysfs_dirent *sysfs_dir_po
pos = NULL;
}
if (!pos && (ino > 1) && (ino < INT_MAX)) {
- pos = parent_sd->s_dir.children;
- while (pos && (ino > pos->s_ino))
- pos = pos->s_sibling;
+ struct rb_node *p = parent_sd->s_dir.inode_tree.rb_node;
+ while (p) {
+#define node rb_entry(p, struct sysfs_dirent, inode_node)
+ if (ino < node->s_ino) {
+ pos = node;
+ p = node->inode_node.rb_left;
+ } else if (ino > node->s_ino) {
+ p = node->inode_node.rb_right;
+ } else {
+ pos = node;
+ break;
+ }
+#undef node
+ }
+ }
+ while (pos && pos->s_ns && pos->s_ns != ns) {
+ struct rb_node *p = rb_next(&pos->inode_node);
+ if (!p)
+ pos = NULL;
+ else
+ pos = rb_entry(p, struct sysfs_dirent, inode_node);
}
- while (pos && pos->s_ns && pos->s_ns != ns)
- pos = pos->s_sibling;
return pos;
}

@@ -938,10 +946,13 @@ static struct sysfs_dirent *sysfs_dir_ne
struct sysfs_dirent *parent_sd, ino_t ino, struct sysfs_dirent *pos)
{
pos = sysfs_dir_pos(ns, parent_sd, ino, pos);
- if (pos)
- pos = pos->s_sibling;
- while (pos && pos->s_ns && pos->s_ns != ns)
- pos = pos->s_sibling;
+ if (pos) do {
+ struct rb_node *p = rb_next(&pos->inode_node);
+ if (!p)
+ pos = NULL;
+ else
+ pos = rb_entry(p, struct sysfs_dirent, inode_node);
+ } while (pos && pos->s_ns && pos->s_ns != ns);
return pos;
}

Index: linux-3.0-fast/fs/sysfs/sysfs.h
================================================== =================
--- linux-3.0-fast.orig/fs/sysfs/sysfs.h 2011-07-25 23:41:10.000000000 +0200
+++ linux-3.0-fast/fs/sysfs/sysfs.h 2011-07-25 23:41:13.000000000 +0200
@@ -18,11 +18,10 @@ struct sysfs_open_dirent;
/* type-specific structures for sysfs_dirent->s_* union members */
struct sysfs_elem_dir {
struct kobject *kobj;
- /* children list starts here and goes through sd->s_sibling */
- struct sysfs_dirent *children;

unsigned long subdirs;

+ struct rb_root inode_tree;
struct rb_root name_tree;
};

@@ -61,9 +60,9 @@ struct sysfs_dirent {
struct lockdep_map dep_map;
#endif
struct sysfs_dirent *s_parent;
- struct sysfs_dirent *s_sibling;
const char *s_name;

+ struct rb_node inode_node;
struct rb_node name_node;

union {

--
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