Re: [PATCH] cpu hotplug issue

Jan Kiszka
2011-08-02T10:24:26Z

On 2011-08-02 11:46, Vasilis Liaskovitis wrote:
> Hi,
>
> On Thu, Jul 28, 2011 at 6:52 PM, Jan Kiszka <jan.kiszka@siemens.com> wrote:
>> On 2011-07-27 18:35, Vasilis Liaskovitis wrote:
>>> Hi,
>>>
>>> On Mon, Jul 25, 2011 at 3:18 PM, Jan Kiszka <jan.kiszka@siemens.com> wrote:
>>> Applying these 3 patches + hacks/fix on master doesn't solve the
>>> initial "CPU: not responding" dmesg hotplug issue on my setup.
>>> The ACPI event is delivered correctly, but "echo 1 >
>>> /sys/devices/system/cpu/cpuX/online" still fails.
>>> e.g. tested with "-smp 1,maxcpus=2"
>>>
>>> Could you share your qemu-kvm command line?
>>
>> Nothing special:
>>
>> qemu-system-x86_64 /my/image -m 1G -snapshot -smp 2,maxcpus=3 \
>> -cpu host,-kvmclock
>>
>
> ok, I have tested the patched qemu-kvm (guestOS ubuntu 10.10 with
> 2.6.35-24-generic kernel) with:
>
> qemu-system-x86_64 /my/image -m 1G -smp 1,maxcpus=2 \
> -cpu host,-kvmclock
>
> on 2 different physical hosts. On the first one:
>
> vendor_id : GenuineIntel
> cpu family : 6
> model : 37
> model name : Intel(R) Core(TM) i3 CPU M 370 @ 2.40GHz
>
> cpu hotplug works ok. When onlining (echo 1 >
> /sys/devices/system/cpu/cpu1/online) dmesg shows:
>
> Booting Node 0 Processor 1 APIC 0x1
> TSC synchronization [CPU#0 -> CPU#1]:
> Measured 3573498937792 cycles TSC warp between CPUs, turning off TSC clock.
> Marking TSC unstable due to check_tsc_sync_source failed
> kvm-clock: cpu 1, msr 0:1f15901, secondary cpu clock

Strange. Why does it still talk about kvm-clock?

>
> on the second system:
>
> vendor_id : AuthenticAMD
> cpu family : 16
> model : 4
> model name : AMD Phenom(tm) II X4 955 Processor
>
> onlining fails:
>
> Booting Node 0 Processor 1 APIC 0x1
> CPU1: Not Responding.
>
> When I specify -kvmclock on the qemu command line for the AMD system,
> it seems that the clocksource on the guest is hpet.
> Dmesg on guest shows "Switching to clocksource hpet" and
> /sys/devices/system/clocksource/clocksource0/current_clocksource
> confirms.
>
> When I don't specify -kvmclock, then the guest clocksource is actually
> kvm-clock. But the onlining problem persists.
>
> I have also tried a newer guestOS (debian-testing with 2.6.39 or 3.0.0
> kernel) on the second system, same problem.
>
> Also: what physical host have you used for testing?

Intel(R) Core(TM) i7 CPU M 620 @ 2.67GHz

FWIW, I've pushed my tree here:

git://git.kiszka.org/qemu-kvm.git queues/cpu-hotplug

Jan

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