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| author | Nick Piggin <nickpiggin@yahoo.com.au> | 2006-03-25 03:07:09 -0800 |
|---|---|---|
| committer | Linus Torvalds <torvalds@g5.osdl.org> | 2006-03-25 08:22:53 -0800 |
| commit | c32ccd87bfd1414b0aabfcd8dbc7539ad23bcbaa (patch) | |
| tree | 612dc637976cbe36e8b72924a1f7bd76e75463fd /include/linux/dcache.h | |
| parent | bf36b9011e3c5b2739f9da2f6de8a6fa3edded32 (diff) | |
| download | lwn-c32ccd87bfd1414b0aabfcd8dbc7539ad23bcbaa.tar.gz lwn-c32ccd87bfd1414b0aabfcd8dbc7539ad23bcbaa.zip | |
[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 <npiggin@suse.de>
Cc: Robert Love <rml@novell.com>
Cc: John McCutchan <ttb@tentacle.dhs.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'include/linux/dcache.h')
| -rw-r--r-- | include/linux/dcache.h | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/include/linux/dcache.h b/include/linux/dcache.h index 4361f3789975..d10bd30c337e 100644 --- a/include/linux/dcache.h +++ b/include/linux/dcache.h @@ -162,6 +162,8 @@ d_iput: no no no yes #define DCACHE_REFERENCED 0x0008 /* Recently used, don't discard. */ #define DCACHE_UNHASHED 0x0010 +#define DCACHE_INOTIFY_PARENT_WATCHED 0x0020 /* Parent inode is watched */ + extern spinlock_t dcache_lock; /** |