From: Michael Ellerman <mpe@ellerman.id.au>
To: "Ruediger Oertel" <ro@suse.de>,
"Nicholas Piggin" <npiggin@gmail.com>,
linuxppc-dev@lists.ozlabs.org,
"Michal Suchánek" <msuchanek@suse.de>
Subject: Re: KVM on POWER8 host lock up since 10d91611f426 ("powerpc/64s: Reimplement book3s idle code in C")
Date: Mon, 31 Aug 2020 22:58:49 +1000 [thread overview]
Message-ID: <87v9gz0y5y.fsf@mpe.ellerman.id.au> (raw)
In-Reply-To: <50693d7e-6c8b-4908-d003-25b99a867850@suse.de>
Ruediger Oertel <ro@suse.de> writes:
> Am 31.08.20 um 03:14 schrieb Nicholas Piggin:
>> Excerpts from Michal Suchánek's message of August 31, 2020 6:11 am:
>>> Hello,
>>>
>>> on POWER8 KVM hosts lock up since commit 10d91611f426 ("powerpc/64s:
>>> Reimplement book3s idle code in C").
>>>
>>> The symptom is host locking up completely after some hours of KVM
>>> workload with messages like
>>>
>>> 2020-08-30T10:51:31+00:00 obs-power8-01 kernel: KVM: couldn't grab cpu 47
>>> 2020-08-30T10:51:31+00:00 obs-power8-01 kernel: KVM: couldn't grab cpu 71
>>> 2020-08-30T10:51:31+00:00 obs-power8-01 kernel: KVM: couldn't grab cpu 47
>>> 2020-08-30T10:51:31+00:00 obs-power8-01 kernel: KVM: couldn't grab cpu 71
>>> 2020-08-30T10:51:31+00:00 obs-power8-01 kernel: KVM: couldn't grab cpu 47
>>>
>>> printed before the host locks up.
>>>
>>> The machines run sandboxed builds which is a mixed workload resulting in
>>> IO/single core/mutiple core load over time and there are periods of no
>>> activity and no VMS runnig as well. The VMs are shortlived so VM
>>> setup/terdown is somewhat excercised as well.
>>>
>>> POWER9 with the new guest entry fast path does not seem to be affected.
>>>
>>> Reverted the patch and the followup idle fixes on top of 5.2.14 and
>>> re-applied commit a3f3072db6ca ("powerpc/powernv/idle: Restore IAMR
>>> after idle") which gives same idle code as 5.1.16 and the kernel seems
>>> stable.
>>>
>>> Config is attached.
>>>
>>> I cannot easily revert this commit, especially if I want to use the same
>>> kernel on POWER8 and POWER9 - many of the POWER9 fixes are applicable
>>> only to the new idle code.
>>>
>>> Any idea what can be the problem?
>>
>> So hwthread_state is never getting back to to HWTHREAD_IN_IDLE on
>> those threads. I wonder what they are doing. POWER8 doesn't have a good
>> NMI IPI and I don't know if it supports pdbg dumping registers from the
>> BMC unfortunately. Do the messages always come in pairs of CPUs?
>>
>> I'm not sure where to start with reproducing, I'll have to try. How many
>> vCPUs in the guests? Do you have several guests running at once?
>
> Hello all,
>
> some details on the setup...
> these machines are buildservice workers, (build.opensuse.org) and all they
> do is spawn new VMs, run a package building job inside (rpmbuild, debbuild,...)
>
> The machines are running in OPAL/PowerNV mode, with "ppc64_cpu --smt=off".
> The number of VMs varies across the machines:
> obs-power8-01: 18 instances, "-smp 16,threads=8"
> obs-power8-02: 20 instances, "-smp 8,threads=8"
> obs-power8-03: 30 instances, "-smp 8,threads=8"
> obs-power8-04: 20 instances, "-smp 8,threads=8"
Can you send us the output of:
# grep . /sys/module/kvm_hv/parameters/*
cheers
next prev parent reply other threads:[~2020-08-31 13:02 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-08-30 20:11 KVM on POWER8 host lock up since 10d91611f426 ("powerpc/64s: Reimplement book3s idle code in C") Michal Suchánek
2020-08-31 1:14 ` Nicholas Piggin
2020-08-31 8:48 ` Ruediger Oertel
2020-08-31 12:58 ` Michael Ellerman [this message]
2020-08-31 13:13 ` Ruediger Oertel
2020-08-31 9:03 ` Ruediger Oertel
2020-08-31 9:07 ` Michal Suchánek
2020-08-31 9:15 ` Michal Suchánek
2020-08-31 10:50 ` Michael Ellerman
2020-09-07 13:13 ` Nicholas Piggin
2020-09-07 13:25 ` Michal Suchánek
2020-10-16 20:14 ` Michal Suchánek
2020-10-19 1:00 ` Nicholas Piggin
2020-10-19 4:50 ` Nicholas Piggin
2020-10-21 17:00 ` Michal Suchánek
2021-01-14 12:40 ` Michal Suchánek
2021-01-14 13:08 ` Nicholas Piggin
2021-11-02 15:48 ` Michal Suchánek
2021-11-05 1:47 ` Nicholas Piggin
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