Messages in this thread | | | Subject | Re: [patch] voluntary-preempt-2.6.9-rc1-bk4-Q9 | From | Thomas Charbonnel <> | Date | Thu, 02 Sep 2004 16:38:33 +0200 |
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Ingo Molnar wrote :
> do you have the NMI watchdog enabled? That could help us debugging this. > Enabling the APIC/IO_APIC and using nmi_watchdog=1 would be the ideal > solution - if that doesnt work then nmi_watchdog=2 would be fine too, > but remove this code from arch/i386/kernel/nmi.c: > > if (nmi_watchdog == NMI_LOCAL_APIC) > nmi_hz = 1; > > (otherwise nmi_watchdog=2 would result in one NMI per second, not enough > to shed light on the above 2.8 msec latency.) > > Ingo
nmi_watchdog=1 worked fine. Here's a trace (there seem to be a counter overflow) :
preemption latency trace v1.0.5 on 2.6.9-rc1-VP-Q9 -------------------------------------------------- latency: 539 us, entries: 38 (38) ----------------- | task: swapper/0, uid:0 nice:0 policy:0 rt_prio:0 ----------------- => started at: do_IRQ+0x19/0x190 => ended at: do_IRQ+0x14a/0x190 =======> 00010000 0.000ms (+0.000ms): do_IRQ (common_interrupt) 00010000 0.000ms (+0.000ms): do_IRQ (default_idle) 00010000 0.000ms (+0.000ms): do_IRQ (<00000000>) 00010001 0.000ms (+0.002ms): mask_and_ack_8259A (do_IRQ) 00010001 0.002ms (+0.000ms): generic_redirect_hardirq (do_IRQ) 00010000 0.002ms (+0.000ms): generic_handle_IRQ_event (do_IRQ) 00010000 0.002ms (+0.000ms): timer_interrupt (generic_handle_IRQ_event) 00010001 0.003ms (+0.005ms): mark_offset_tsc (timer_interrupt) 00010001 0.008ms (+0.000ms): do_timer (timer_interrupt) 00010001 0.008ms (+0.000ms): update_process_times (do_timer) 00010001 0.008ms (+0.000ms): update_one_process (update_process_times) 00010001 0.009ms (+0.000ms): run_local_timers (update_process_times) 00010001 0.009ms (+0.000ms): raise_softirq (update_process_times) 00010001 0.009ms (+0.000ms): scheduler_tick (update_process_times) 00010001 0.009ms (+0.000ms): sched_clock (scheduler_tick) 00010001 0.009ms (+0.000ms): update_wall_time (do_timer) 00010001 0.009ms (+0.000ms): update_wall_time_one_tick (update_wall_time) 00010001 0.010ms (+0.000ms): generic_note_interrupt (do_IRQ) 00010001 0.010ms (+0.000ms): end_8259A_irq (do_IRQ) 00010001 0.010ms (+0.000ms): enable_8259A_irq (do_IRQ) 00000001 0.011ms (+0.524ms): do_softirq (do_IRQ) 00000001 0.535ms (+0.000ms): do_nmi (mcount) 00010001 0.536ms (+0.000ms): profile_tick (nmi_watchdog_tick) 00010001 0.536ms (+0.000ms): profile_hook (profile_tick) 00010002 0.536ms (+0.000ms): notifier_call_chain (profile_hook) 00010001 0.537ms (+689953.062ms): profile_hit (nmi_watchdog_tick) 00000002 689953.599ms (+1.523ms): sched_clock (activate_task) 00000001 0.537ms (+0.000ms): wake_up_process (do_softirq) 00000001 0.537ms (+0.000ms): try_to_wake_up (wake_up_process) 00000001 0.537ms (+0.000ms): task_rq_lock (try_to_wake_up) 00000002 0.537ms (+0.000ms): activate_task (try_to_wake_up) 00000002 0.538ms (+0.000ms): sched_clock (activate_task) 00000002 0.538ms (+0.000ms): recalc_task_prio (activate_task) 00000002 0.538ms (+0.000ms): effective_prio (recalc_task_prio) 00000002 0.538ms (+0.000ms): enqueue_task (activate_task) 00000001 0.538ms (+0.000ms): preempt_schedule (try_to_wake_up) 00000001 0.539ms (+0.000ms): sub_preempt_count (do_IRQ) 00000001 0.539ms (+0.000ms): update_max_trace (check_preempt_timing)
Thomas
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