Not yet mainlined in the Linux kernel but currently queued as part of the x86/cpu changes for next round is the ability for the kernel to detect split locks and either warn the offending applications or kill the processes.
Split locks are when an atomic instruction operates on data spanning multiple cache lines. Due to the atomic nature, a global bus lock is needed when working on two cache lines and that in turn causes a big performance hit for the overall system performance. This Linux kernel support for detecting split locks is contingent upon x86_64 CPUs supporting the capability for generating alignment check exceptions (#AC) on encountering a split lock. For now the necessary MSR appears to be only supported on Intel CPUs.
[Source: Phoronix]
