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/inotify.h | 11 +++++++++++ 1 file changed, 11 insertions(+) (limited to 'include/linux/inotify.h') diff --git a/include/linux/inotify.h b/include/linux/inotify.h index 267c88b5f742..09e00433c78e 100644 --- a/include/linux/inotify.h +++ b/include/linux/inotify.h @@ -71,6 +71,8 @@ struct inotify_event { #ifdef CONFIG_INOTIFY +extern void inotify_d_instantiate(struct dentry *, struct inode *); +extern void inotify_d_move(struct dentry *); extern void inotify_inode_queue_event(struct inode *, __u32, __u32, const char *); extern void inotify_dentry_parent_queue_event(struct dentry *, __u32, __u32, @@ -81,6 +83,15 @@ extern u32 inotify_get_cookie(void); #else +static inline void inotify_d_instantiate(struct dentry *dentry, + struct inode *inode) +{ +} + +static inline void inotify_d_move(struct dentry *dentry) +{ +} + static inline void inotify_inode_queue_event(struct inode *inode, __u32 mask, __u32 cookie, const char *filename) -- cgit v1.2.3