preemption latency trace v1.0.2
-------------------------------
 latency: 424 us, entries: 21 (21)
    -----------------
    | task: ksoftirqd/0/2, uid:0 nice:-10 policy:1 rt_prio:96
    -----------------
 => started at: mdio_read+0x49/0x290
 => ended at:   local_bh_enable+0x17/0xa0
=======>
00000100 0.000ms (+0.000ms): mdio_read (vortex_timer)
00000101 0.000ms (+0.000ms): mdio_sync (mdio_read)
00010101 0.086ms (+0.086ms): do_IRQ (mdio_sync)
00010102 0.086ms (+0.000ms): mask_and_ack_level_ioapic_irq (do_IRQ)
00010102 0.086ms (+0.000ms): mask_IO_APIC_irq (mask_and_ack_level_ioapic_irq)
00010103 0.086ms (+0.000ms): __mask_IO_APIC_irq (mask_IO_APIC_irq)
00010103 0.086ms (+0.000ms): __modify_IO_APIC_irq (__mask_IO_APIC_irq)
00010102 0.091ms (+0.004ms): generic_redirect_hardirq (do_IRQ)
00010102 0.091ms (+0.000ms): wake_up_process (generic_redirect_hardirq)
00010102 0.091ms (+0.000ms): try_to_wake_up (wake_up_process)
00010102 0.092ms (+0.000ms): task_rq_lock (try_to_wake_up)
00010103 0.092ms (+0.000ms): activate_task (try_to_wake_up)
00010103 0.092ms (+0.000ms): sched_clock (activate_task)
00010103 0.092ms (+0.000ms): recalc_task_prio (activate_task)
00010103 0.092ms (+0.000ms): effective_prio (recalc_task_prio)
00010103 0.092ms (+0.000ms): enqueue_task (activate_task)
00000101 0.401ms (+0.308ms): smp_apic_timer_interrupt (mdio_read)
00010101 0.401ms (+0.000ms): profile_hook (smp_apic_timer_interrupt)
00010102 0.401ms (+0.000ms): notifier_call_chain (profile_hook)
00000100 0.424ms (+0.023ms): local_bh_enable (mdio_read)
00000100 0.424ms (+0.000ms): sub_preempt_count (local_bh_enable)