On Thu, Jun 21, 2018 at 01:18:52PM -0700, Fenghua Yu wrote: > On Thu, Jun 21, 2018 at 09:37:38PM +0200, Peter Zijlstra wrote: > > On Sun, May 27, 2018 at 08:45:49AM -0700, Fenghua Yu wrote: > > > Currently we can trace split lock event counter for debug purpose. But > > > > How? A while ago I actually tried that, but I could not find a suitable > > perf event. > > The event name is called sq_misc.split_lock. It's been supported in perf > already.
Thanks. > > > Intel introduces mechanism to detect split lock via alignment > > > check exception in Tremont and other future processors. If split lock is > > > from user process, #AC handler can kill the process or re-execute faulting > > > instruction depending on configuration. > > > > Ideally it would #AC any unaligned (implied) LOCK prefix instruction, > > not just across lines. > > This feature only triggers #AC for unaligned cache line access, not for > other aligned (4 bytes, 8 bytes, etc). This is not explicitly said in > ISE. I can add this info in next version of patches. It was clear; what I'm saying it I'd like #AC to happen for any actual unaligned LOCK access, not just across lines.
