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authorEric Dumazet <dada1@cosmosbay.com>2006-12-06 20:38:48 -0800
committerLinus Torvalds <torvalds@woody.osdl.org>2006-12-07 08:39:41 -0800
commitb3423415fbc2e5461605826317da1c8dbbf21f97 (patch)
treed7e129545515846526d72072322ad405a4b7a41b
parentd18de5a2721f84ffd6a5d637915746ed47becc1c (diff)
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[PATCH] dcache: avoid RCU for never-hashed dentries
Some dentries don't need to be globally visible in dentry hashtable. (pipes & sockets) Such dentries dont need to wait for a RCU grace period at delete time. Being able to free them permits a better CPU cache use (hot cache) This patch combined with (dont insert pipe dentries into dentry_hashtable) reduced time of { pipe(p); close(p[0]); close(p[1]);} on my UP machine (1.6 GHz Pentium-M) from 3.23 us to 2.86 us (But this patch does not depend on other patches, only bench results) Signed-off-by: Eric Dumazet <dada1@cosmosbay.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Maneesh Soni <maneesh@in.ibm.com> Cc: "Paul E. McKenney" <paulmck@us.ibm.com> Cc: Dipankar Sarma <dipankar@in.ibm.com> Acked-by: David Miller <davem@davemloft.net> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
-rw-r--r--fs/dcache.c16
1 files changed, 12 insertions, 4 deletions
diff --git a/fs/dcache.c b/fs/dcache.c
index a7c67cee5d8..d68631f18df 100644
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -68,15 +68,19 @@ struct dentry_stat_t dentry_stat = {
.age_limit = 45,
};
-static void d_callback(struct rcu_head *head)
+static void __d_free(struct dentry *dentry)
{
- struct dentry * dentry = container_of(head, struct dentry, d_u.d_rcu);
-
if (dname_external(dentry))
kfree(dentry->d_name.name);
kmem_cache_free(dentry_cache, dentry);
}
+static void d_callback(struct rcu_head *head)
+{
+ struct dentry * dentry = container_of(head, struct dentry, d_u.d_rcu);
+ __d_free(dentry);
+}
+
/*
* no dcache_lock, please. The caller must decrement dentry_stat.nr_dentry
* inside dcache_lock.
@@ -85,7 +89,11 @@ static void d_free(struct dentry *dentry)
{
if (dentry->d_op && dentry->d_op->d_release)
dentry->d_op->d_release(dentry);
- call_rcu(&dentry->d_u.d_rcu, d_callback);
+ /* if dentry was never inserted into hash, immediate free is OK */
+ if (dentry->d_hash.pprev == NULL)
+ __d_free(dentry);
+ else
+ call_rcu(&dentry->d_u.d_rcu, d_callback);
}
/*