[CentOS-virt] Nested KVM issue

Laurentiu Soica

laurentiu at soica.ro
Tue Aug 23 05:30:31 UTC 2016


I've tried the kernel-lt with same results.
For kernel-ml, the baremetal wasn't able to boot at that time.

În mar., 23 aug. 2016 la 02:22, Adi Pircalabu <adi at ddns.com.au> a scris:

> Laurentiu,
>
> Just to chip in, without thoroughly checking the thread (which I'd like
> to apologize in advance for): have you tried to test other kernel
> instead of the stock one? You can have a look at
> http://elrepo.org/tiki/kernel-ml and http://elrepo.org/tiki/kernel-lt
> and use them for some comparison testing.
> Cheers,
>
> ---
> Adi Pircalabu
>
> On 22-08-2016 18:31, Laurentiu Soica wrote:
> > No luck with qemu-kvm-ev, the behavior is the same. Running perf
> > record -a -g on the baremetal shows that most of the CPU time is in
> > _raw_spin_lock
> >
> >   Children      Self  Command          Shared Object
> > Symbol
> >                                                     -  93.62%
> > 93.62%  qemu-kvm         [kernel.kallsyms]            [k]
> > _raw_spin_lock
> >
> >
> >    - _raw_spin_lock
> >
> >
> >       + 45.30% kvm_mmu_sync_roots
> >
> >
> >       + 28.49% kvm_mmu_load
> >
> >
> >       + 25.00% mmu_free_roots
> >
> >
> >       + 1.12% tdp_page_fault
> >
> > În joi, 18 aug. 2016 la 11:59, Laurentiu Soica a
> > scris:
> >
> >> I've tried with KSM disabled and nothing changed.
> >>
> >> I've upgraded KVM to qemu-kvm-ev. I'm waiting to see if there are
> >> any improvements and report back.
> >>
> >> În mie., 17 aug. 2016 la 15:10, Boris Derzhavets
> >> <bderzhavets at hotmail.com> a scris:
> >>
> >> For myself KSM is unpredictable feature. The problem is Compute,
> >> just this node
> >>
> >> does "copy on write" , so only Compute.
> >>
> >> My concern exactly is where would it lead to worse or better Guest
> >> behavior ?
> >>
> >> I am not expecting complete fix.  I would track via top/htop  and
> >> dmesg via Cron on 1-2 hr
> >>
> >> period.
> >>
> >> -------------------------
> >>
> >> FROM: centos-virt-bounces at centos.org
> >> <centos-virt-bounces at centos.org> on behalf of Laurentiu Soica
> >> <laurentiu at soica.ro>
> >>
> >> SENT: Wednesday, August 17, 2016 6:38 AM
> >>
> >> TO: Discussion about the virtualization on CentOS
> >> SUBJECT: Re: [CentOS-virt] Nested KVM issue
> >>
> >> Both baremetal and compute ? Are there any other metrics do you
> >> consider useful to collect for troubleshooting purposes ?
> >>
> >> În mie., 17 aug. 2016 la 13:04, Boris Derzhavets
> >> a scris:
> >>
> >> It sounds weird, but attempt to disable KSM and see would it help or
> >> no ?
> >>
> >> -------------------------
> >>
> >> FROM: centos-virt-bounces at centos.org
> >> <centos-virt-bounces at centos.org> on behalf of Laurentiu Soica
> >>
> >> SENT: Wednesday, August 17, 2016 4:56 AM
> >>
> >> TO: Discussion about the virtualization on CentOS
> >> SUBJECT: Re: [CentOS-virt] Nested KVM issue
> >>
> >> Enabled the logging on both compute and baremetal. Nothing strange
> >> in logs:
> >>
> >> on baremetal :
> >>
> >> Wed Aug 17 11:51:01 EEST 2016: committed 62310764 free 58501808
> >> Wed Aug 17 11:51:01 EEST 2016: 87025667 < 123574516 and free >
> >> 24714903, stop ksm
> >>
> >> on compute:
> >>
> >> Wed Aug 17 08:52:52 UTC 2016: committed 24547132 free 76730936
> >> Wed Aug 17 08:52:52 UTC 2016: 45139624 < 102962460 and free >
> >> 20592492, stop ksm
> >>
> >> and the compute node is again at 100% CPU utilization.
> >>
> >> În mar., 16 aug. 2016 la 15:26, Boris Derzhavets
> >> a scris:
> >>
> >> I would enable ksmtuned logging ,if it has been done verify logs
> >>
> >> -------------------------
> >>
> >> FROM: centos-virt-bounces at centos.org
> >> <centos-virt-bounces at centos.org> on behalf of Laurentiu Soica
> >>
> >> SENT: Tuesday, August 16, 2016 7:16 AM
> >>
> >> TO: Discussion about the virtualization on CentOS
> >> SUBJECT: Re: [CentOS-virt] Nested KVM issue
> >>
> >> Yes. It is on both baremetal and compute node.
> >>
> >> _______________________________________________
> >> CentOS-virt mailing list
> >> CentOS-virt at centos.org
> >> https://lists.centos.org/mailman/listinfo/centos-virt
> >  _______________________________________________
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> >
> > --
> >
> > Laurentiu Soica
> > _______________________________________________
> > CentOS-virt mailing list
> > CentOS-virt at centos.org
> > https://lists.centos.org/mailman/listinfo/centos-virt
>
-- 
Laurentiu Soica
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