The patch is not about DTrace functionality, but about infrastructure use in one particular place. http://people.freebsd.org/~avg/dtrace_gethrtime_init.diff I believe that sched_pin() is need there to make sure that "host"/base CPU stays the same for all calls to smp_rendezvous_cpus(). The pc_cpumask should just be a cosmetic change. -- Andriy Gapon