Comment 2 for bug 1488426

perf report:

+ 73.46% 0.00% kworker/2:0 [kernel.kallsyms] [k] ret_from_fork
+ 73.46% 0.00% kworker/2:0 [kernel.kallsyms] [k] kthread
+ 73.46% 0.00% kworker/2:0 [kernel.kallsyms] [k] worker_thread
+ 73.35% 0.10% kworker/2:0 [kernel.kallsyms] [k] process_one_work
+ 72.13% 0.07% kworker/2:0 [kernel.kallsyms] [k] rpm_idle
+ 71.68% 0.09% kworker/2:0 [kernel.kallsyms] [k] rpm_suspend
+ 71.52% 0.02% kworker/2:0 [kernel.kallsyms] [k] pm_runtime_work
+ 71.30% 0.06% kworker/2:0 [kernel.kallsyms] [k] __rpm_callback
+ 71.26% 0.00% kworker/2:0 [kernel.kallsyms] [k] usb_runtime_idle
+ 71.23% 0.02% kworker/2:0 [kernel.kallsyms] [k] __pm_runtime_suspend
+ 70.96% 0.00% kworker/2:0 [kernel.kallsyms] [k] rpm_callback
+ 70.91% 0.01% kworker/2:0 [kernel.kallsyms] [k] usb_runtime_suspend
+ 70.86% 0.04% kworker/2:0 [kernel.kallsyms] [k] usb_suspend_both
+ 68.64% 0.01% kworker/2:0 [kernel.kallsyms] [k] usb_resume_interface.isra.6
+ 68.63% 0.02% kworker/2:0 [kernel.kallsyms] [k] hub_resume
+ 68.59% 0.44% kworker/2:0 [kernel.kallsyms] [k] hub_activate
+ 67.22% 0.28% kworker/2:0 [kernel.kallsyms] [k] hub_port_status
+ 66.42% 0.32% kworker/2:0 [kernel.kallsyms] [k] usb_control_msg
+ 63.88% 0.24% kworker/2:0 [kernel.kallsyms] [k] usb_start_wait_urb
+ 58.25% 0.08% kworker/2:0 [kernel.kallsyms] [k] usb_submit_urb
+ 58.14% 0.44% kworker/2:0 [kernel.kallsyms] [k] usb_submit_urb.part.6
+ 56.05% 1.75% kworker/2:0 [kernel.kallsyms] [k] usb_hcd_submit_urb
+ 43.00% 42.17% kworker/2:0 [kernel.kallsyms] [k] xhci_hub_control
+ 15.27% 0.00% ksoftirqd/2 [kernel.kallsyms] [k] ret_from_fork
+ 15.27% 0.00% ksoftirqd/2 [kernel.kallsyms] [k] kthread
+ 14.88% 0.95% ksoftirqd/2 [kernel.kallsyms] [k] smpboot_thread_fn
+ 8.78% 0.54% kworker/2:0 [kernel.kallsyms] [k] usb_hcd_giveback_urb
+ 7.35% 0.78% kworker/2:0 [kernel.kallsyms] [k] __tasklet_schedule
+ 7.19% 0.05% kworker/2:0 [kernel.kallsyms] [k] wakeup_softirqd
+ 7.16% 0.14% kworker/2:0 [kernel.kallsyms] [k] wake_up_process
+ 7.00% 0.12% ksoftirqd/2 [kernel.kallsyms] [k] run_ksoftirqd
+ 6.91% 0.11% ksoftirqd/2 [kernel.kallsyms] [k] schedule
+ 6.69% 0.76% ksoftirqd/2 [kernel.kallsyms] [k] __do_softirq
+ 6.56% 1.33% ksoftirqd/2 [kernel.kallsyms] [k] __schedule
+ 6.47% 0.49% kworker/2:0 [kernel.kallsyms] [k] try_to_wake_up
+ 5.37% 5.37% kworker/2:0 [kernel.kallsyms] [k] __switch_to
+ 5.30% 0.91% ksoftirqd/2 [kernel.kallsyms] [k] tasklet_action
+ 5.15% 5.15% ksoftirqd/2 [kernel.kallsyms] [k] __switch_to
+ 5.09% 0.11% kworker/2:0 [kernel.kallsyms] [k] ttwu_do_activate.constprop.94
+ 5.04% 0.28% kworker/2:0 [kernel.kallsyms] [k] _cond_resched
+ 4.83% 0.34% kworker/2:0 [kernel.kallsyms] [k] wait_for_completion_timeout
+ 4.70% 1.68% kworker/2:0 [kernel.kallsyms] [k] __schedule