This is the third and final patchset that deals with reducing the amount of contention we impose on the ipc lock (kern_ipc_perm.lock). These changes mostly deal with shared memory, previous work has already been done for semaphores and message queues: http://lkml.org/lkml/2013/3/20/546 (sems) http://lkml.org/lkml/2013/5/15/584 (mqueues) With these patches applied, a custom shm microbenchmark stressing shmctl doing IPC_STAT with 4 threads a million times, reduces the execution time by 50%. A similar run, this time with IPC_SET, reduces the execution time from 3 mins and 35 secs to 27 seconds. Patches 1-8: replaces blindly taking the ipc lock for a smarter combination of rcu and ipc_obtain_object, only acquiring the spinlock when updating. Patch 9: renames the ids rw_mutex to rwsem, which is what it already was. Patch 10: is a trivial mqueue leftover cleanup Patch 11: adds a brief lock scheme description, requested by Andrew. This patchset applies on top of linux-next (3.10.0-rc6-next-20130618). Davidlohr Bueso (11): ipc,shm: introduce lockless functions to obtain the ipc object ipc,shm: shorten critical region in shmctl_down ipc: drop ipcctl_pre_down ipc,shm: introduce shmctl_nolock ipc,shm: make shmctl_nolock lockless ipc,shm: shorten critical region for shmctl ipc,shm: cleanup do_shmat pasta ipc,shm: shorten critical region for shmat ipc: rename ids->rw_mutex ipc,msg: drop msg_unlock ipc: document general ipc locking scheme include/linux/ipc_namespace.h | 2 +- ipc/msg.c | 25 +++-- ipc/namespace.c | 4 +- ipc/sem.c | 24 ++--- ipc/shm.c | 239 ++++++++++++++++++++++++++---------------- ipc/util.c | 57 +++++----- ipc/util.h | 7 +- 7 files changed, 199 insertions(+), 159 deletions(-) -- 1.7.11.7 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>