The patch titled
Subject: procfs: use faster rb_first_cached()
has been added to the -mm tree. Its filename is
procfs-use-faster-rb_first_cached.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/procfs-use-faster-rb_first_cached.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/procfs-use-faster-rb_first_cached.patch
Before you just go and hit "reply", please:
a) Consider who else should be cc'ed
b) Prefer to cc a suitable mailing list as well
c) Ideally: find the original patch on the mailing list and do a
reply-to-all to that, adding suitable additional cc's
*** Remember to use Documentation/SubmitChecklist when testing your code ***
The -mm tree is included into linux-next and is updated
there every 3-4 working days
------------------------------------------------------
From: Davidlohr Bueso <dave@xxxxxxxxxxxx>
Subject: procfs: use faster rb_first_cached()
... such that we can avoid the tree walks to get the node with the
smallest key. Semantically the same, as the previously used rb_first(),
but O(1). The main overhead is the extra footprint for the cached rb_node
pointer, which should not matter for procfs.
Link: http://lkml.kernel.org/r/20170719014603.19029-14-dave@xxxxxxxxxxxx
Signed-off-by: Davidlohr Bueso <dbueso@xxxxxxx>
Acked-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
fs/proc/generic.c | 26 ++++++++++++++------------
fs/proc/internal.h | 2 +-
fs/proc/proc_net.c | 2 +-
fs/proc/root.c | 2 +-
4 files changed, 17 insertions(+), 15 deletions(-)
diff -puN fs/proc/generic.c~procfs-use-faster-rb_first_cached fs/proc/generic.c
--- a/fs/proc/generic.c~procfs-use-faster-rb_first_cached
+++ a/fs/proc/generic.c
@@ -40,8 +40,8 @@ static int proc_match(unsigned int len,
static struct proc_dir_entry *pde_subdir_first(struct proc_dir_entry *dir)
{
- return rb_entry_safe(rb_first(&dir->subdir), struct proc_dir_entry,
- subdir_node);
+ return rb_entry_safe(rb_first_cached(&dir->subdir),
+ struct proc_dir_entry, subdir_node);
}
static struct proc_dir_entry *pde_subdir_next(struct proc_dir_entry *dir)
@@ -54,7 +54,7 @@ static struct proc_dir_entry *pde_subdir
const char *name,
unsigned int len)
{
- struct rb_node *node = dir->subdir.rb_node;
+ struct rb_node *node = dir->subdir.rb_root.rb_node;
while (node) {
struct proc_dir_entry *de = rb_entry(node,
@@ -75,8 +75,9 @@ static struct proc_dir_entry *pde_subdir
static bool pde_subdir_insert(struct proc_dir_entry *dir,
struct proc_dir_entry *de)
{
- struct rb_root *root = &dir->subdir;
- struct rb_node **new = &root->rb_node, *parent = NULL;
+ struct rb_root_cached *root = &dir->subdir;
+ struct rb_node **new = &root->rb_root.rb_node, *parent = NULL;
+ bool leftmost = true;
/* Figure out where to put new node */
while (*new) {
@@ -88,15 +89,16 @@ static bool pde_subdir_insert(struct pro
parent = *new;
if (result < 0)
new = &(*new)->rb_left;
- else if (result > 0)
+ else if (result > 0) {
new = &(*new)->rb_right;
- else
+ leftmost = false;
+ } else
return false;
}
/* Add new node and rebalance tree. */
rb_link_node(&de->subdir_node, parent, new);
- rb_insert_color(&de->subdir_node, root);
+ rb_insert_color_cached(&de->subdir_node, root, leftmost);
return true;
}
@@ -369,7 +371,7 @@ static struct proc_dir_entry *__proc_cre
ent->namelen = qstr.len;
ent->mode = mode;
ent->nlink = nlink;
- ent->subdir = RB_ROOT;
+ ent->subdir = RB_ROOT_CACHED;
atomic_set(&ent->count, 1);
spin_lock_init(&ent->pde_unload_lock);
INIT_LIST_HEAD(&ent->pde_openers);
@@ -545,7 +547,7 @@ void remove_proc_entry(const char *name,
de = pde_subdir_find(parent, fn, len);
if (de)
- rb_erase(&de->subdir_node, &parent->subdir);
+ rb_erase_cached(&de->subdir_node, &parent->subdir);
write_unlock(&proc_subdir_lock);
if (!de) {
WARN(1, "name '%s'\n", name);
@@ -582,13 +584,13 @@ int remove_proc_subtree(const char *name
write_unlock(&proc_subdir_lock);
return -ENOENT;
}
- rb_erase(&root->subdir_node, &parent->subdir);
+ rb_erase_cached(&root->subdir_node, &parent->subdir);
de = root;
while (1) {
next = pde_subdir_first(de);
if (next) {
- rb_erase(&next->subdir_node, &de->subdir);
+ rb_erase_cached(&next->subdir_node, &de->subdir);
de = next;
continue;
}
diff -puN fs/proc/internal.h~procfs-use-faster-rb_first_cached fs/proc/internal.h
--- a/fs/proc/internal.h~procfs-use-faster-rb_first_cached
+++ a/fs/proc/internal.h
@@ -40,7 +40,7 @@ struct proc_dir_entry {
const struct inode_operations *proc_iops;
const struct file_operations *proc_fops;
struct proc_dir_entry *parent;
- struct rb_root subdir;
+ struct rb_root_cached subdir;
struct rb_node subdir_node;
void *data;
atomic_t count; /* use count */
diff -puN fs/proc/proc_net.c~procfs-use-faster-rb_first_cached fs/proc/proc_net.c
--- a/fs/proc/proc_net.c~procfs-use-faster-rb_first_cached
+++ a/fs/proc/proc_net.c
@@ -196,7 +196,7 @@ static __net_init int proc_net_ns_init(s
if (!netd)
goto out;
- netd->subdir = RB_ROOT;
+ netd->subdir = RB_ROOT_CACHED;
netd->data = net;
netd->nlink = 2;
netd->namelen = 3;
diff -puN fs/proc/root.c~procfs-use-faster-rb_first_cached fs/proc/root.c
--- a/fs/proc/root.c~procfs-use-faster-rb_first_cached
+++ a/fs/proc/root.c
@@ -210,7 +210,7 @@ struct proc_dir_entry proc_root = {
.proc_iops = &proc_root_inode_operations,
.proc_fops = &proc_root_operations,
.parent = &proc_root,
- .subdir = RB_ROOT,
+ .subdir = RB_ROOT_CACHED,
.name = "/proc",
};
_
Patches currently in -mm which might be from dave@xxxxxxxxxxxx are
rbtree-cache-leftmost-node-internally.patch
rbtree-optimize-root-check-during-rebalancing-loop.patch
rbtree-add-some-additional-comments-for-rebalancing-cases.patch
lib-rbtree_testc-make-input-module-parameters.patch
lib-rbtree_testc-add-inorder-traversal-test.patch
lib-rbtree_testc-support-rb_root_cached.patch
sched-fair-replace-cfs_rq-rb_leftmost.patch
sched-deadline-replace-earliest-dl-and-rq-leftmost-caching.patch
locking-rtmutex-replace-top-waiter-and-pi_waiters-leftmost-caching.patch
block-cfq-replace-cfq_rb_root-leftmost-caching.patch
lib-interval_tree-fast-overlap-detection.patch
lib-interval-tree-correct-comment-wrt-generic-flavor.patch
procfs-use-faster-rb_first_cached.patch
fs-epoll-use-faster-rb_first_cached.patch
mem-memcg-cache-rightmost-node.patch
block-cfq-cache-rightmost-rb_node.patch
--
To unsubscribe from this list: send the line "unsubscribe mm-commits" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
