perf top -g -U --sort=symbol --children == lalalalala?

[Mike Galbraith <umgwanakikbuti@gmail.com>]

Seems the now default on --children thingy doesn't like -U much. 

Samples: 5K of event 'cycles', Event count (approx.): 2268660922
  Children      Self  Symbol
+   46.42%     0.04%  [k] system_call_fastpath
+   27.12%     0.80%  [k] apic_timer_interrupt
+   26.26%     0.23%  [k] smp_apic_timer_interrupt
+   20.43%     0.13%  [k] local_apic_timer_interrupt
+   20.20%     0.74%  [k] hrtimer_interrupt
+   18.01%     0.39%  [k] __run_hrtimer
+   14.43%     0.35%  [k] tick_sched_timer
+   13.60%     0.05%  [k] sys_poll
+   13.09%     1.16%  [k] do_sys_poll
+   12.16%     0.08%  [k] tick_sched_handle.isra.16
+   11.70%     0.32%  [k] update_process_times
+   11.41%     0.03%  [k] sys_read
+   11.17%     0.11%  [k] vfs_read
+   10.85%     0.09%  [k] seq_read
+    8.27%     0.09%  [k] proc_single_show
+    7.79%     1.19%  [k] page_fault
+    7.01%     0.25%  [k] scheduler_tick
+    6.26%     0.11%  [k] __do_page_fault
+    5.97%     1.33%  [k] do_task_stat
+    5.91%     0.23%  [k] handle_mm_fault
+    5.40%     0.20%  [k] do_sys_open
+    5.02%     0.09%  [k] ret_from_intr
+    4.94%     0.05%  [k] do_IRQ
+    4.70%     0.14%  [k] path_openat
+    4.69%     0.62%  [k] tty_poll
+    4.69%     0.16%  [k] irq_exit
+    4.49%     0.63%  [k] __do_softirq
+    4.27%     0.12%  [k] __alloc_pages_nodemask
+    3.95%     0.03%  [k] handle_irq_event_percpu
+    3.51%     0.71%  [k] __fget_light
+    3.47%     0.04%  [k] sys_select
+    3.39%     0.08%  [k] seq_printf
+    3.37%     0.07%  [k] sys_open
+    3.34%     0.11%  [k] seq_vprintf
+    3.22%     0.02%  [k] core_sys_select
+    3.15%     0.26%  [k] do_select
+    3.15%     3.15%  [k] _raw_spin_lock