diff options
Diffstat (limited to 'fs/btrfs/locking.c')
| -rw-r--r-- | fs/btrfs/locking.c | 13 |
1 files changed, 13 insertions, 0 deletions
diff --git a/fs/btrfs/locking.c b/fs/btrfs/locking.c index 0cc314c10d6..e30aa6e2958 100644 --- a/fs/btrfs/locking.c +++ b/fs/btrfs/locking.c @@ -25,6 +25,15 @@ #include "extent_io.h" #include "locking.h" +/* + * locks the per buffer mutex in an extent buffer. This uses adaptive locks + * and the spin is not tuned very extensively. The spinning does make a big + * difference in almost every workload, but spinning for the right amount of + * time needs some help. + * + * In general, we want to spin as long as the lock holder is doing btree searches, + * and we should give up if they are in more expensive code. + */ int btrfs_tree_lock(struct extent_buffer *eb) { int i; @@ -57,6 +66,10 @@ int btrfs_tree_locked(struct extent_buffer *eb) return mutex_is_locked(&eb->mutex); } +/* + * btrfs_search_slot uses this to decide if it should drop its locks + * before doing something expensive like allocating free blocks for cow. + */ int btrfs_path_lock_waiting(struct btrfs_path *path, int level) { int i; |