[linux-audio-user] Graphics card an realtime performance

[Gerrit Niestijl]

> The only reliable way to debug this stuff is with the latency tracer
> (see the list archives for details).

Here is a latency trace. I started sooperlooper with it's gui and loaded
a loop. After a fem minutes some xruns occur that throw sooperlooper out
of jack. The trace is from immediately after this. Does this reveal
anything?

gerrit


preemption latency trace v1.1.5 on 2.6.14-rt22-debugy
--------------------------------------------------------------------
 latency: 89 us, #64/64, CPU#0 | (M:rt VP:0, KP:0, SP:1 HP:1)
    -----------------
    | task: softirq-timer/0-3 (uid:0 nice:0 policy:1 rt_prio:1)
    -----------------

                 _------=> CPU#            
                / _-----=> irqs-off        
               | / _----=> need-resched    
               || / _---=> hardirq/softirq 
               ||| / _--=> preempt-depth   
               |||| /                      
               |||||     delay             
   cmd     pid ||||| time  |   caller      
      \   /    |||||   \   |   /           
sooperlo-5783  0D...    1us : common_interrupt ((0))
sooperlo-5783  0D.h.    3us+: do_IRQ (80713f8 0 0)
sooperlo-5783  0D.h1    6us+: mask_and_ack_8259A (__do_IRQ)
sooperlo-5783  0D.h1   12us+: redirect_hardirq (__do_IRQ)
sooperlo-5783  0D.h.   14us : handle_IRQ_event (__do_IRQ)
sooperlo-5783  0D.h.   16us : timer_interrupt (handle_IRQ_event)
sooperlo-5783  0D.h.   17us : io_apic_timer_ack (timer_interrupt)
sooperlo-5783  0D.h.   18us : handle_tick_update (timer_interrupt)
sooperlo-5783  0D.h1   20us : do_timer (handle_tick_update)
sooperlo-5783  0D.h.   21us : update_process_times (handle_tick_update)
sooperlo-5783  0D.h.   22us : account_user_time (update_process_times)
sooperlo-5783  0D.h.   23us : run_local_timers (update_process_times)
sooperlo-5783  0D.h.   25us : raise_softirq (run_local_timers)
sooperlo-5783  0D.h.   26us+: wakeup_softirqd (raise_softirq)
sooperlo-5783  0D.h.   28us : wake_up_process (wakeup_softirqd)
sooperlo-5783  0D.h.   29us+: try_to_wake_up (wake_up_process)
sooperlo-5783  0D.h1   31us : activate_task (try_to_wake_up)
sooperlo-5783  0D.h1   31us : sched_clock (activate_task)
sooperlo-5783  0D.h1   33us+: recalc_task_prio (activate_task)
sooperlo-5783  0D.h1   36us : __recalc_task_prio (recalc_task_prio)
sooperlo-5783  0D.h1   37us : __recalc_task_prio <<...>-3> (62 62)
sooperlo-5783  0D.h1   38us : activate_task <<...>-3> (62 7)
sooperlo-5783  0D.h1   39us+: enqueue_task (activate_task)
sooperlo-5783  0Dnh1   41us : try_to_wake_up <<...>-3> (62 74)
sooperlo-5783  0Dnh.   42us : preempt_schedule (try_to_wake_up)
sooperlo-5783  0Dnh.   43us : wake_up_process (wakeup_softirqd)
sooperlo-5783  0Dnh.   44us : rcu_pending (update_process_times)
sooperlo-5783  0Dnh.   46us : scheduler_tick (update_process_times)
sooperlo-5783  0Dnh.   47us+: sched_clock (scheduler_tick)
sooperlo-5783  0Dnh1   49us+: task_timeslice (scheduler_tick)
sooperlo-5783  0Dnh.   51us+: preempt_schedule (scheduler_tick)
sooperlo-5783  0Dnh1   53us : note_interrupt (__do_IRQ)
sooperlo-5783  0Dnh1   55us+: enable_8259A_irq (__do_IRQ)
sooperlo-5783  0Dnh1   57us : preempt_schedule (enable_8259A_irq)
sooperlo-5783  0Dnh.   57us : preempt_schedule (__do_IRQ)
sooperlo-5783  0Dnh.   58us : irq_exit (do_IRQ)
sooperlo-5783  0Dn..   59us : __schedule (work_resched)
sooperlo-5783  0Dn..   60us : profile_hit (__schedule)
sooperlo-5783  0Dn.1   60us+: sched_clock (__schedule)
   <...>-3     0D..2   65us+: __switch_to (__schedule)
   <...>-3     0D..2   68us : __schedule <sooperlo-5783> (74 62)
   <...>-3     0D.h2   70us : do_IRQ (c039a4f4 9 0)
   <...>-3     0D.h3   71us+: mask_and_ack_8259A (__do_IRQ)
   <...>-3     0D.h3   78us : redirect_hardirq (__do_IRQ)
   <...>-3     0D.h3   79us : wake_up_process (redirect_hardirq)
   <...>-3     0D.h3   79us : try_to_wake_up (wake_up_process)
   <...>-3     0D.h4   80us : activate_task (try_to_wake_up)
   <...>-3     0D.h4   80us : sched_clock (activate_task)
   <...>-3     0D.h4   80us : recalc_task_prio (activate_task)
   <...>-3     0D.h4   81us : __recalc_task_prio (recalc_task_prio)
   <...>-3     0D.h4   82us : __recalc_task_prio <<...>-14> (1d 1d)
   <...>-3     0D.h4   82us : activate_task <<...>-14> (1d 8)
   <...>-3     0D.h4   83us : enqueue_task (activate_task)
   <...>-3     0Dnh4   83us : try_to_wake_up <<...>-14> (1d 62)
   <...>-3     0Dnh3   84us : preempt_schedule (try_to_wake_up)
   <...>-3     0Dnh3   84us : wake_up_process (redirect_hardirq)
   <...>-3     0Dnh2   84us : preempt_schedule (__do_IRQ)
   <...>-3     0Dnh2   85us : irq_exit (do_IRQ)
   <...>-3     0Dn.2   85us < (608)
   <...>-3     0.n.1   87us : preempt_schedule (__schedule)
   <...>-3     0.n.1   87us : sub_preempt_count (__schedule)
   <...>-3     0.n.1   89us : sub_preempt_count_ti (sub_preempt_count)


vim:ft=help