LKML Archive on lore.kernel.org
 help / Atom feed
From: Davidlohr Bueso <dave@stgolabs.net>
To: akpm@linux-foundation.org
Cc: mingo@kernel.org, peterz@infradead.org, jack@suse.cz,
	torvalds@linux-foundation.org, kirill.shutemov@linux.intel.com,
	hch@infradead.org, ldufour@linux.vnet.ibm.com, mhocko@suse.com,
	mgorman@techsingularity.net, dave@stgolabs.net,
	linux-kernel@vger.kernel.org, Davidlohr Bueso <dbueso@suse.de>
Subject: [PATCH 13/17] procfs: use faster rb_first_cached()
Date: Tue, 18 Jul 2017 18:45:59 -0700
Message-ID: <20170719014603.19029-14-dave@stgolabs.net> (raw)
In-Reply-To: <20170719014603.19029-1-dave@stgolabs.net>

... 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.

Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Davidlohr Bueso <dbueso@suse.de>
---
 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 --git a/fs/proc/generic.c b/fs/proc/generic.c
index e3cda0b5968f..ab6496356dc2 100644
--- a/fs/proc/generic.c
+++ b/fs/proc/generic.c
@@ -40,8 +40,8 @@ static int proc_match(unsigned int len, const char *name, struct proc_dir_entry
 
 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_find(struct proc_dir_entry *dir,
 					      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_find(struct proc_dir_entry *dir,
 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 proc_dir_entry *dir,
 		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_create(struct proc_dir_entry **parent,
 	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, struct proc_dir_entry *parent)
 
 	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, struct proc_dir_entry *parent)
 		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 --git a/fs/proc/internal.h b/fs/proc/internal.h
index aa2b89071630..8382d08385a9 100644
--- a/fs/proc/internal.h
+++ b/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 --git a/fs/proc/proc_net.c b/fs/proc/proc_net.c
index d72fc40241d9..a2bf369c923d 100644
--- a/fs/proc/proc_net.c
+++ b/fs/proc/proc_net.c
@@ -196,7 +196,7 @@ static __net_init int proc_net_ns_init(struct net *net)
 	if (!netd)
 		goto out;
 
-	netd->subdir = RB_ROOT;
+	netd->subdir = RB_ROOT_CACHED;
 	netd->data = net;
 	netd->nlink = 2;
 	netd->namelen = 3;
diff --git a/fs/proc/root.c b/fs/proc/root.c
index deecb397daa3..926fb27f4ca2 100644
--- a/fs/proc/root.c
+++ b/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",
 };
 
-- 
2.12.0

  parent reply index

Thread overview: 27+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-07-19  1:45 [PATCH -next v4 00/17] rbtree: cache leftmost node internally Davidlohr Bueso
2017-07-19  1:45 ` [PATCH 01/17] " Davidlohr Bueso
2017-07-19  1:45 ` [PATCH 02/17] rbtree: optimize root-check during rebalancing loop Davidlohr Bueso
2017-07-19  1:45 ` [PATCH 03/17] rbtree: add some additional comments for rebalancing cases Davidlohr Bueso
2017-07-19  1:45 ` [PATCH 04/17] lib/rbtree_test.c: make input module parameters Davidlohr Bueso
2017-07-19  1:45 ` [PATCH 05/17] lib/rbtree_test.c: add (inorder) traversal test Davidlohr Bueso
2017-07-19  1:45 ` [PATCH 06/17] lib/rbtree_test.c: support rb_root_cached Davidlohr Bueso
2017-07-19  1:45 ` [PATCH 07/17] sched/fair: replace cfs_rq->rb_leftmost Davidlohr Bueso
2017-07-19  1:45 ` [PATCH 08/17] sched/deadline: replace earliest dl and rq leftmost caching Davidlohr Bueso
2017-07-19  1:45 ` [PATCH 09/17] locking/rtmutex: replace top-waiter and pi_waiters " Davidlohr Bueso
2017-07-19  1:45 ` [PATCH 10/17] block/cfq: replace cfq_rb_root " Davidlohr Bueso
2017-07-19  7:46   ` Jan Kara
2017-07-19  1:45 ` [PATCH 11/17] lib/interval_tree: fast overlap detection Davidlohr Bueso
2017-07-22 17:52   ` Doug Ledford
2017-08-01 17:16   ` Michael S. Tsirkin
2017-07-19  1:45 ` [PATCH 12/17] lib/interval-tree: correct comment wrt generic flavor Davidlohr Bueso
2017-07-19  1:45 ` Davidlohr Bueso [this message]
2017-07-19  1:46 ` [PATCH 14/17] fs/epoll: use faster rb_first_cached() Davidlohr Bueso
2017-07-19  1:46 ` [PATCH 15/17] fs/ext4: use cached rbtrees Davidlohr Bueso
2017-07-19  7:40   ` Jan Kara
2017-07-19 22:50     ` Davidlohr Bueso
2017-07-19  1:46 ` [PATCH 16/17] mem/memcg: cache rightmost node Davidlohr Bueso
2017-07-19  7:50   ` Michal Hocko
2017-07-26 21:09     ` Andrew Morton
2017-07-27  7:06       ` Michal Hocko
2017-07-19  1:46 ` [PATCH 17/17] block/cfq: cache rightmost rb_node Davidlohr Bueso
2017-07-19  7:59   ` Jan Kara

Reply instructions:

You may reply publically to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20170719014603.19029-14-dave@stgolabs.net \
    --to=dave@stgolabs.net \
    --cc=akpm@linux-foundation.org \
    --cc=dbueso@suse.de \
    --cc=hch@infradead.org \
    --cc=jack@suse.cz \
    --cc=kirill.shutemov@linux.intel.com \
    --cc=ldufour@linux.vnet.ibm.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=mgorman@techsingularity.net \
    --cc=mhocko@suse.com \
    --cc=mingo@kernel.org \
    --cc=peterz@infradead.org \
    --cc=torvalds@linux-foundation.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

LKML Archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/lkml/0 lkml/git/0.git
	git clone --mirror https://lore.kernel.org/lkml/1 lkml/git/1.git
	git clone --mirror https://lore.kernel.org/lkml/2 lkml/git/2.git
	git clone --mirror https://lore.kernel.org/lkml/3 lkml/git/3.git
	git clone --mirror https://lore.kernel.org/lkml/4 lkml/git/4.git
	git clone --mirror https://lore.kernel.org/lkml/5 lkml/git/5.git
	git clone --mirror https://lore.kernel.org/lkml/6 lkml/git/6.git
	git clone --mirror https://lore.kernel.org/lkml/7 lkml/git/7.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 lkml lkml/ https://lore.kernel.org/lkml \
		linux-kernel@vger.kernel.org linux-kernel@archiver.kernel.org
	public-inbox-index lkml


Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/org.kernel.vger.linux-kernel


AGPL code for this site: git clone https://public-inbox.org/ public-inbox