CPUF_SYNCTSC
atomic_or_uint(&ci->ci_flags, CPUF_SYNCTSC);
while ((ci->ci_flags & CPUF_SYNCTSC) != 0) {
while ((ci->ci_flags & CPUF_SYNCTSC) == 0) {
atomic_and_uint(&ci->ci_flags, ~CPUF_SYNCTSC);