From c32ccd87bfd1414b0aabfcd8dbc7539ad23bcbaa Mon Sep 17 00:00:00 2001 From: Nick Piggin Date: Sat, 25 Mar 2006 03:07:09 -0800 Subject: [PATCH] inotify: lock avoidance with parent watch status in dentry Previous inotify work avoidance is good when inotify is completely unused, but it breaks down if even a single watch is in place anywhere in the system. Robin Holt notices that udev is one such culprit - it slows down a 512-thread application on a 512 CPU system from 6 seconds to 22 minutes. Solve this by adding a flag in the dentry that tells inotify whether or not its parent inode has a watch on it. Event queueing to parent will skip taking locks if this flag is cleared. Setting and clearing of this flag on all child dentries versus event delivery: this is no in terms of race cases, and that was shown to be equivalent to always performing the check. The essential behaviour is that activity occuring _after_ a watch has been added and _before_ it has been removed, will generate events. Signed-off-by: Nick Piggin Cc: Robert Love Cc: John McCutchan Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/fsnotify.h | 19 +++++++++++++++++++ 1 file changed, 19 insertions(+) (limited to 'include/linux/fsnotify.h') diff --git a/include/linux/fsnotify.h b/include/linux/fsnotify.h index 03b8e79..f7e517c 100644 --- a/include/linux/fsnotify.h +++ b/include/linux/fsnotify.h @@ -17,6 +17,25 @@ #include /* + * fsnotify_d_instantiate - instantiate a dentry for inode + * Called with dcache_lock held. + */ +static inline void fsnotify_d_instantiate(struct dentry *entry, + struct inode *inode) +{ + inotify_d_instantiate(entry, inode); +} + +/* + * fsnotify_d_move - entry has been moved + * Called with dcache_lock and entry->d_lock held. + */ +static inline void fsnotify_d_move(struct dentry *entry) +{ + inotify_d_move(entry); +} + +/* * fsnotify_move - file old_name at old_dir was moved to new_name at new_dir */ static inline void fsnotify_move(struct inode *old_dir, struct inode *new_dir, -- cgit v1.1