RE: 2.6.10-mm3 scaling problem with inotify

[Robert Love <rml@novell.com>]

On Fri, 2005-01-14 at 10:31 +0800, Zou, Nanhai wrote:

(your email wraps badly)

>  There is still a little difference between your implement in
>  inotify_dentry_parent_queue_event from dnotify_parent
>  
>  In dnotify_parent, if parent is not watching the event, the code will
> not fall
>  through dget and dput path.
>  
>  While in inotify_dentry_parent_queue_event kernel will go dget and dput
> even
>  if (inode->inotify_data == NULL).
>  
>  While dget and dput will introduce a lot of atomic operations..
>  And the most important, dput will grab global dcache_lock...,
>  I think that is the reason why John Hawkes saw great performance drop.
>  
>  Simply follow dnotify_parent, only call dget and dput when
> inode->inotify_data != NULL will solve this problem I think.

This is what I meant in the original email.  This is the dnotify
difference I was talking about.

The patch I submitted should put the two in parity.

	Robert Love