On Sat, 29 November 2008 09:45:09 +0100, Eric Dumazet wrote:

 
+void iput_single(struct inode *inode)
+{
+	if (atomic_dec_and_test(&inode->i_count)) {
+		destroy_inode(inode);
+		percpu_counter_dec(&nr_inodes);
+	}
+}

I wonder if it is possible to avoid the atomic_dec_and_test() here, at
least in the common case, and combine it with the atomic_dec_and_test()
of the dentry.  A quick look at fs/inode.c indicates that inode->i_count
may never get changed for a SINGLE inode, except during creation or
deletion.

It might be worth to
- remove the conditional from iput_single() and measure that it makes a
  difference,
- poison SINGLE inodes with some value and
- put a BUG_ON() in __iget() that checks for the poison value.

I _think_ the BUG_ON() is unnecessary, but at least my brain is not
sufficient to convince me.  Can inotify somehow get a hold of a socket?
Or dquot (how insane would that be?)

Jörn

-- 
Mac is for working,
Linux is for Networking,
Windows is for Solitaire!
-- stolen from dc