usdt:$MMTK:mmtk:alloc_slow_once_start {
    if (@stats_enabled) {
        @alloc_slow_nsecs[tid] = nsecs;
    }
}

usdt:$MMTK:mmtk:alloc_slow_once_end {
    if (@stats_enabled) {
        @alloc_slow_hist = hist((nsecs - @alloc_slow_nsecs[tid])/400);
    }
}