Anticipatory I/O scheduler author Nick Piggin [interview] has been maintaining a lockless pagecache patch for many months. In March he provided a draft document that details the lockless radix-tree utilized by the pagecache [pdf], in which it describes the Read-Copy Update (RCU) algorithm used to share a dynamic data structure without using locks. Jens Axboe recently posted some benchmark results demonstrating some workloads that benefit from the lockless pagecache.
Link: KernelTrap.org
