This patchset supports a generic mechanism to atomically update a reference count that is protected by a spinlock without actually acquiring the lock itself. If the update doesn't succeeed, the caller will have to acquire the lock and update the reference count in the the old way. This will help in situation where there is a lot of spinlock contention because of frequent reference count update. The new mechanism was designed in such a way to easily retrofit into existing code with minimal changes. Both the spinlock and the reference count can be accessed in the same way as before. The d_lock and d_count fields of the struct dentry in dcache.h was modified to use the new mechanism. This serves as an example of how to convert existing spinlock and reference count combo to use the new way of locklessly updating the reference count. Signed-off-by: Waiman Long <Waiman.Long@xxxxxx> Waiman Long (2): spinlock: New spinlock_refcount.h for lockless update of refcount dcache: Locklessly update d_count whenever possible fs/dcache.c | 14 +++- include/linux/dcache.h | 22 +++++- include/linux/spinlock_refcount.h | 145 +++++++++++++++++++++++++++++++++++++ include/linux/spinlock_types.h | 19 +++++ 4 files changed, 196 insertions(+), 4 deletions(-) create mode 100644 include/linux/spinlock_refcount.h -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
