From: Nick Piggin <npiggin@kernel.dk>
To: linux-fsdevel@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Subject: [patch 25/28] fs: dcache reduce prune_one_dentry locking
Date: Wed, 17 Nov 2010 01:09:25 +1100 [thread overview]
Message-ID: <20101116142030.612454500@kernel.dk> (raw)
In-Reply-To: 20101116140900.039761100@kernel.dk
[-- Attachment #1: dcache-prune_one_dentry-less-lock.patch --]
[-- Type: text/plain, Size: 1562 bytes --]
prune_one_dentry can avoid quite a bit of locking in the common case where
ancestors have an elevated refcount. Alternatively, we could have gone the
other way and made fewer trylocks in the case where d_count goes to zero, but
is probably less common.
Signed-off-by: Nick Piggin <npiggin@kernel.dk>
---
fs/dcache.c | 27 +++++++++++++++------------
1 file changed, 15 insertions(+), 12 deletions(-)
Index: linux-2.6/fs/dcache.c
===================================================================
--- linux-2.6.orig/fs/dcache.c 2010-11-17 00:52:38.000000000 +1100
+++ linux-2.6/fs/dcache.c 2010-11-17 01:05:38.000000000 +1100
@@ -547,26 +547,29 @@ static void prune_one_dentry(struct dent
* Prune ancestors.
*/
while (dentry) {
- spin_lock(&dcache_inode_lock);
-again:
+relock:
spin_lock(&dentry->d_lock);
+ if (dentry->d_count > 1) {
+ dentry->d_count--;
+ spin_unlock(&dentry->d_lock);
+ return;
+ }
+ if (!spin_trylock(&dcache_inode_lock)) {
+relock2:
+ spin_unlock(&dentry->d_lock);
+ cpu_relax();
+ goto relock;
+ }
+
if (IS_ROOT(dentry))
parent = NULL;
else
parent = dentry->d_parent;
if (parent && !spin_trylock(&parent->d_lock)) {
- spin_unlock(&dentry->d_lock);
- goto again;
- }
- dentry->d_count--;
- if (dentry->d_count) {
- if (parent)
- spin_unlock(&parent->d_lock);
- spin_unlock(&dentry->d_lock);
spin_unlock(&dcache_inode_lock);
- return;
+ goto relock2;
}
-
+ dentry->d_count--;
dentry_lru_del(dentry);
__d_drop(dentry);
dentry = d_kill(dentry, parent);
next prev parent reply other threads:[~2010-11-16 14:26 UTC|newest]
Thread overview: 46+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-11-16 14:09 [patch 00/28] [rfc] dcache scaling part 1 Nick Piggin
2010-11-16 14:09 ` [patch 01/28] fs: d_validate fixes Nick Piggin
2010-11-17 10:44 ` Andi Kleen
2010-11-18 20:51 ` David Miller
2010-11-18 20:59 ` David Miller
2010-11-19 5:05 ` Nick Piggin
2010-11-19 5:01 ` Nick Piggin
2010-11-16 14:09 ` [patch 02/28] kernel: kmem_ptr_validate considered harmful Nick Piggin
2010-11-16 14:09 ` [patch 03/28] fs: dcache documentation cleanup Nick Piggin
2010-11-16 14:09 ` [patch 04/28] fs: change d_delete semantics Nick Piggin
2010-11-17 0:16 ` Tim Pepper
2010-11-16 14:09 ` [patch 05/28] cifs: dont overwrite dentry name in d_revalidate Nick Piggin
2010-11-16 14:09 ` [patch 06/28] jfs: " Nick Piggin
2010-11-16 14:09 ` [patch 07/28] fs: change d_compare for rcu-walk Nick Piggin
2010-11-17 0:44 ` Tim Pepper
2010-11-16 14:09 ` [patch 08/28] fs: change d_hash " Nick Piggin
2010-11-17 0:50 ` Tim Pepper
2010-11-16 14:09 ` [patch 09/28] hostfs: simplify locking Nick Piggin
2010-11-16 14:09 ` [patch 10/28] fs: dcache scale hash Nick Piggin
2010-11-16 14:09 ` [patch 11/28] fs: dcache scale lru Nick Piggin
2010-11-16 14:09 ` [patch 12/28] fs: dcache scale dentry refcount Nick Piggin
2010-11-16 14:09 ` [patch 13/28] fs: dcache scale d_unhashed Nick Piggin
2010-11-19 19:41 ` Tim Pepper
2010-11-16 14:09 ` [patch 14/28] fs: dcache scale subdirs Nick Piggin
2010-11-19 19:41 ` Tim Pepper
2010-11-16 14:09 ` [patch 15/28] fs: scale inode alias list Nick Piggin
2010-11-19 19:41 ` Tim Pepper
2010-11-16 14:09 ` [patch 16/28] fs: Use rename lock and RCU for multi-step operations Nick Piggin
2010-11-19 19:42 ` Tim Pepper
2010-11-16 14:09 ` [patch 17/28] fs: increase d_name lock coverage Nick Piggin
2010-11-16 14:09 ` [patch 18/28] fs: dcache remove dcache_lock Nick Piggin
2010-11-16 14:09 ` [patch 19/28] fs: dcache avoid starvation in dcache multi-step operations Nick Piggin
2010-11-16 14:09 ` [patch 20/28] fs: dcache reduce dput locking Nick Piggin
2010-11-16 14:09 ` [patch 21/28] fs: dcache reduce locking in d_alloc Nick Piggin
2010-11-16 14:09 ` [patch 22/28] fs: dcache reduce dcache_inode_lock Nick Piggin
2010-11-16 14:09 ` [patch 23/28] fs: dcache rationalise dget variants Nick Piggin
2010-11-16 14:09 ` [patch 24/28] fs: dcache reduce d_parent locking Nick Piggin
2010-11-16 14:09 ` Nick Piggin [this message]
2010-11-16 14:09 ` [patch 26/28] fs: reduce dcache_inode_lock width in lru scanning Nick Piggin
2010-11-16 14:09 ` [patch 27/28] fs: use RCU in shrink_dentry_list to reduce lock nesting Nick Piggin
2010-11-16 14:09 ` [patch 28/28] fs: consolidate dentry kill sequence Nick Piggin
2010-11-17 2:12 ` [patch 00/28] [rfc] dcache scaling part 1 Dave Chinner
2010-11-17 10:56 ` Andi Kleen
2010-11-17 11:19 ` Nick Piggin
2010-11-17 12:01 ` Andi Kleen
2010-11-19 19:43 ` Tim Pepper
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