Messages in this thread | | | Date | Mon, 30 Jul 2012 14:43:14 +0200 | From | Sasha Levin <> | Subject | Re: rcu: INFO: rcu_preempt detected stalls on CPUs/tasks on v3.6 |
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On 07/30/2012 11:33 AM, Avi Kivity wrote: > On 07/30/2012 12:13 PM, Sasha Levin wrote: >>>>>> >>>>>> Yup, looks like it. kvm_stats is something like this: >>>>>> >>>>>> kvm_entry 142104033 939393 >>>>>> kvm_exit 142104004 939390 >>>>>> kvm_apic 84781115 582714 >>>>>> kvm_msr 84682085 582714 >>>>>> kvm_apic_accept_irq 65219959 522263 >>>>>> kvm_inj_virq 43173709 291385 >>>>>> >>>>>> With everything else at 0 when it happens. >>>>> >>>>> Please run a trace and verify that the injected vector is indeed the >>>>> timer interrupt. >>>> >>>> Looks like it is. >>>> >>>>> Then work backwards to see the last place it is >>>>> programmed (APIC_TMICT/APIC_TDCR). >>>> >>>> This looks like what you're looking for: >>>> >>>> kvm_apic: apic_write APIC_TMICT = 0x3e > > What about APIC_TMICT? Might be configured just once on boot.
Did you mean APIC_TDCR?
I'm seeing both in the trace logs, but it's APIC_TMICT thats shown when the hang occurs.
vm-19727 [002] ...1 66669.010699: kvm_apic: apic_read APIC_TDCR = 0x0 vm-19727 [002] ...1 66669.010699: kvm_msr: msr_read 83e = 0x0 vm-19727 [002] d..2 66669.010699: kvm_entry: vcpu 0 vm-19727 [002] d..2 66669.010700: kvm_exit: reason MSR_WRITE rip 0xffffffff810a06a8 info 0 0 vm-19727 [002] ...1 66669.010701: kvm_apic: apic_write APIC_TDCR = 0x3 vm-19727 [002] ...1 66669.010701: kvm_msr: msr_write 83e = 0x3 vm-19727 [002] d..2 66669.010701: kvm_entry: vcpu 0
>>>> >>>> >>>> Basically it's spinning on the following 4 lines of trace when it happens: >>>> >>>> 16063.549189: kvm_apic: apic_write APIC_TMICT = 0x3e >>>> 16063.549190: kvm_msr: msr_write 838 = 0x3e >>>> 16063.549190: kvm_exit: reason EXTERNAL_INTERRUPT rip 0xffffffff8115de02 info 0 0 >>>> 16063.549190: kvm_entry: vcpu 2 >>>> >>> >>> What, no kvm_inj_virq? >>> >>> Are you running with pveoi? Try disabling it. > > What's the answer to this question?
The host is running 3.5, so that shouldn't be enabled.
>> >> I must have looked at a block in the logfile which doesn't represent everything thats going on, sorry. >> >> Here's a more complete picture: >> >> vm-16567 [000] d..2 16063.549298: kvm_exit: reason PENDING_INTERRUPT rip 0xffffffff83625c80 info 0 0 >> vm-16567 [000] ...1 16063.549299: kvm_inj_virq: irq 239 >> vm-16567 [000] d..2 16063.549300: kvm_entry: vcpu 0 >> vm-16567 [000] d..2 16063.549301: kvm_exit: reason MSR_WRITE rip 0xffffffff8109fef8 info 0 0 >> vm-16567 [000] ...1 16063.549302: kvm_apic: apic_write APIC_EOI = 0x0 >> vm-16567 [000] ...1 16063.549302: kvm_msr: msr_write 80b = 0x0 >> vm-16567 [000] d..2 16063.549303: kvm_entry: vcpu 0 >> vm-16567 [000] d..2 16063.549308: kvm_exit: reason MSR_WRITE rip 0xffffffff8109fef8 info 0 0 >> vm-16567 [000] ...1 16063.549309: kvm_apic: apic_write APIC_TMICT = 0x3e >> vm-16567 [000] ...1 16063.549310: kvm_msr: msr_write 838 = 0x3e >> vm-16567 [000] d..2 16063.549311: kvm_entry: vcpu 0 >> vm-16567 [000] d..2 16063.549312: kvm_exit: reason PENDING_INTERRUPT rip 0xffffffff83625c80 info 0 0 > > This must refer to a lower priority interrupt, since 239 hasn't been > injected yet. > >> vm-16567 [000] ...1 16063.549314: kvm_apic_accept_irq: apicid 0 vec 239 (Fixed|edge) > > And now conveniently the hrtimer fires and injects another interrupt. > >> vm-16567 [000] ...1 16063.549315: kvm_inj_virq: irq 239 >> vm-16567 [000] d..2 16063.549315: kvm_entry: vcpu 0 >> vm-16567 [000] d..2 16063.549316: kvm_exit: reason MSR_WRITE rip 0xffffffff8109fef8 info 0 0 >> vm-16567 [000] ...1 16063.549318: kvm_apic: apic_write APIC_EOI = 0x0 >> vm-16567 [000] ...1 16063.549318: kvm_msr: msr_write 80b = 0x0 > > Please add hrtimer_start and hrtimer_expire_entry to your traced events. >
A bigger log with those two enabled:
vm-19730 [003] ...1 66730.739585: kvm_apic: apic_write APIC_TMICT = 0x3e vm-19716 [000] d..3 66730.739586: hrtimer_start: hrtimer=ffff880133cc3f78 function=posix_timer_fn expires=66882054763626 softexpires=66882054763626 vm-19730 [003] d..2 66730.739586: hrtimer_start: hrtimer=ffff88011e00d3d0 function=kvm_timer_fn expires=66882053774813 softexpires=66882053774813 vm-19730 [003] ...1 66730.739586: kvm_msr: msr_write 838 = 0x3e vm-19730 [003] d..2 66730.739587: kvm_entry: vcpu 3 vm-19730 [003] d..2 66730.739589: kvm_exit: reason PENDING_INTERRUPT rip 0xffffffff8115c684 info 0 0 vm-19729 [001] d..2 66730.739590: kvm_exit: reason MSR_WRITE rip 0xffffffff810a06a8 info 0 0 vm-19730 [003] d.h2 66730.739590: hrtimer_expire_entry: hrtimer=ffff88011e00d3d0 function=kvm_timer_fn now=66882053778032 vm-19729 [001] ...1 66730.739591: kvm_apic: apic_write APIC_TMICT = 0x3e vm-19730 [003] ...1 66730.739591: kvm_apic_accept_irq: apicid 3 vec 239 (Fixed|edge) (coalesced) vm-19729 [001] d..2 66730.739591: hrtimer_start: hrtimer=ffff88020d208490 function=kvm_timer_fn expires=66882053780380 softexpires=66882053780380 vm-19730 [003] ...1 66730.739592: kvm_inj_virq: irq 239 vm-19729 [001] ...1 66730.739592: kvm_msr: msr_write 838 = 0x3e vm-19730 [003] d..2 66730.739593: kvm_entry: vcpu 3 vm-19729 [001] d..2 66730.739593: kvm_entry: vcpu 2 vm-19730 [003] d..2 66730.739594: kvm_exit: reason MSR_WRITE rip 0xffffffff810a06a8 info 0 0 vm-19729 [001] d..2 66730.739594: kvm_exit: reason EXTERNAL_INTERRUPT rip 0xffffffff83601f61 info 0 0 vm-19730 [003] ...1 66730.739595: kvm_apic: apic_write APIC_EOI = 0x0 vm-19730 [003] ...1 66730.739595: kvm_msr: msr_write 80b = 0x0 vm-19729 [001] d.h2 66730.739596: hrtimer_expire_entry: hrtimer=ffff88020d208490 function=kvm_timer_fn now=66882053783462 vm-19730 [003] ...1 66730.739596: kvm_apic_accept_irq: apicid 3 vec 239 (Fixed|edge) vm-19729 [001] ...1 66730.739597: kvm_apic_accept_irq: apicid 2 vec 239 (Fixed|edge) (coalesced) vm-19730 [003] d..2 66730.739597: kvm_entry: vcpu 3 vm-19729 [001] d..2 66730.739597: kvm_entry: vcpu 2 vm-19729 [001] d..2 66730.739598: kvm_exit: reason PENDING_INTERRUPT rip 0xffffffff8115c684 info 0 0 vm-19729 [001] ...1 66730.739599: kvm_apic_accept_irq: apicid 2 vec 239 (Fixed|edge) (coalesced) vm-19729 [001] ...1 66730.739600: kvm_inj_virq: irq 239 vm-19729 [001] d..2 66730.739600: kvm_entry: vcpu 2 vm-19729 [001] d..2 66730.739601: kvm_exit: reason MSR_WRITE rip 0xffffffff810a06a8 info 0 0 vm-19729 [001] ...1 66730.739602: kvm_apic: apic_write APIC_EOI = 0x0 vm-19729 [001] ...1 66730.739602: kvm_msr: msr_write 80b = 0x0 vm-19730 [003] d..2 66730.739603: kvm_exit: reason MSR_WRITE rip 0xffffffff810a06a8 info 0 0 vm-19729 [001] ...1 66730.739603: kvm_apic_accept_irq: apicid 2 vec 239 (Fixed|edge) vm-19730 [003] ...1 66730.739604: kvm_apic: apic_write APIC_TMICT = 0x3e vm-19729 [001] d..2 66730.739604: kvm_entry: vcpu 2 vm-19730 [003] d..2 66730.739604: hrtimer_start: hrtimer=ffff88011e00d3d0 function=kvm_timer_fn expires=66882053793430 softexpires=66882053793430 vm-19730 [003] ...1 66730.739605: kvm_msr: msr_write 838 = 0x3e vm-19730 [003] d..2 66730.739606: kvm_entry: vcpu 3 vm-19730 [003] d..2 66730.739607: kvm_exit: reason PENDING_INTERRUPT rip 0xffffffff8115c684 info 0 0 vm-19729 [001] d..2 66730.739608: kvm_exit: reason EXTERNAL_INTERRUPT rip 0xffffffff8115f2a1 info 0 0 vm-19730 [003] d.h2 66730.739608: hrtimer_expire_entry: hrtimer=ffff88011e00d3d0 function=kvm_timer_fn now=66882053796355 vm-19729 [001] ...1 66730.739609: kvm_userspace_exit: reason restart (4) vm-19730 [003] ...1 66730.739610: kvm_apic_accept_irq: apicid 3 vec 239 (Fixed|edge) (coalesced) vm-19730 [003] ...1 66730.739611: kvm_userspace_exit: reason restart (4) vm-19716 [000] ...1 66730.739612: kvm_set_irq: gsi 4 level 1 source 0 vm-19716 [000] ...2 66730.739614: kvm_pic_set_irq: chip 0 pin 4 (edge)
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