From 5faeb8adb956a5ad6579c4e309e8689943ad8294 Mon Sep 17 00:00:00 2001 From: Jason Low Date: Tue, 21 Jan 2014 15:36:05 -0800 Subject: [PATCH] locking/mcs: Micro-optimize the MCS code, add extra comments Remove unnecessary operation to assign locked status to 1 if lock is acquired without contention. Lock status will not be checked by lock holder again once it is acquired and any lock contenders will not be looking at the lock holder's lock status. Make the cmpxchg(lock, node, NULL) == node check in mcs_spin_unlock() likely() as it is likely that a race did not occur most of the time. Also add in more comments describing how the local node is used in MCS locks. Reviewed-by: Paul E. McKenney Reviewed-by: Tim Chen Signed-off-by: Jason Low Signed-off-by: Tim Chen Signed-off-by: Peter Zijlstra Cc: Linus Torvalds Cc: Andrew Morton Link: http://lkml.kernel.org/r/1390347365.3138.64.camel@schen9-DESK Signed-off-by: Ingo Molnar --- Reading git-format-patch failed