[Xen-users] Re: [Xen-devel] dom0-cpus problem

[George Dunlap <George.Dunlap@xxxxxxxxxxxxx>]

I didn't see the original question; but the "problem" seems to be that
when using xend, xm vcpu-list still shows 8 vcpus for dom0?

The number of cpus for a domain is assigned at creation; in domain 0's
case, this is at boot, necessarily before xend runs.

I suspect what (dom0-cpus 1) does is tell xend to unplug all cpus
except one, by writing "0" into /sys/.../cpus/[1-7]/online.  This will
tell dom0 to take vcpus 1-7 offline, which will put them in a "paused"
state (as you can see from xm vcpu-list); but they're still registered
to dom0 in Xen, and still available to be brought online at any time.

Setting the boot parameter will change the number of vcpus assigned on
VM creation.

 -George

On Wed, Jul 22, 2009 at 4:18 PM, Nerijus Narmontas<n.narmontas@xxxxxxxxx> wrote:
> On Tue, Jul 21, 2009 at 2:01 PM, Pasi Kärkkäinen <pasik@xxxxxx> wrote:
>>
>> On Tue, Jul 21, 2009 at 01:53:25PM +0300, Nerijus Narmontas wrote:
>> > Hello,
>> > If I set (dom0-cpus 1) in /etc/xen/xend-config.sxp, after I gracefully
>> > shutdown domU, the domain stays in ---s- state.
>> >
>> > Is this fixed in 3.4.1-rc8?
>> >
>>
>> Hello.
>>
>> Please don't hijack threads - you replied to a thread about network
>> problems
>> and gplpv drivers. Always start a new thread for new subjects.
>>
>> What version are you seeing this behaviour with? Xen 3.4.0 ? What dom0
>> kernel version?
>>
>> -- Pasi
>
> Sorry for the threads thing.
> root@xen1:/# more /etc/xen/xend-config.sxp | grep cpu
> # In SMP system, dom0 will use dom0-cpus # of CPUS
> # If dom0-cpus = 0, dom0 will take all cpus available
> (dom0-cpus 1)
> root@xen1:/# xm dmesg | grep Command
> (XEN) Command line: console=com2 com2=115200,8n1
> root@xen1:/# xm dmesg | grep VCPUs
> (XEN) Dom0 has maximum 8 VCPUs
> root@xen1:/# xm vcpu-list
> Name                                ID  VCPU   CPU State   Time(s) CPU
> Affinity
> Domain-0                             0     0     5   r--       9.2 any cpu
> Domain-0                             0     1     -   --p       1.8 any cpu
> Domain-0                             0     2     -   --p       1.7 any cpu
> Domain-0                             0     3     -   --p       1.6 any cpu
> Domain-0                             0     4     -   --p       1.4 any cpu
> Domain-0                             0     5     -   --p       1.4 any cpu
> Domain-0                             0     6     -   --p       1.5 any cpu
> Domain-0                             0     7     -   --p       1.3 any cpu
> root@xen1:/# xm create /etc/xen/dc3.conf
> Using config file "/etc/xen/dc3.conf".
> Started domain dc3 (id=1)
> root@xen1:/# xm vcpu-list
> Name                                ID  VCPU   CPU State   Time(s) CPU
> Affinity
> Domain-0                             0     0     7   r--      36.5 any cpu
> Domain-0                             0     1     -   --p       1.8 any cpu
> Domain-0                             0     2     -   --p       1.7 any cpu
> Domain-0                             0     3     -   --p       1.6 any cpu
> Domain-0                             0     4     -   --p       1.4 any cpu
> Domain-0                             0     5     -   --p       1.4 any cpu
> Domain-0                             0     6     -   --p       1.5 any cpu
> Domain-0                             0     7     -   --p       1.3 any cpu
> dc3                                  1     0     0   -b-      15.2 0
> dc3                                  1     1     1   -b-       6.8 1
> dc3                                  1     2     2   -b-       7.5 2
> dc3                                  1     3     3   -b-       8.0 3
> After HVM Windows domU shutdown, it stays in ---s- state.
> root@xen1:/# xm li
> Name                                        ID   Mem VCPUs      State
> Time(s)
> Domain-0                                     0 24106     1     r-----
> 58.7
> dc3                                          1  8192     4     ---s--
> 59.0
> root@xen1:/# xm vcpu-list
> Name                                ID  VCPU   CPU State   Time(s) CPU
> Affinity
> Domain-0                             0     0     4   r--      48.4 any cpu
> ...
> Domain-0                             0     7     -   --p       1.3 any cpu
> dc3                                  1     0     0   ---      20.0 0
> dc3                                  1     1     1   ---      10.9 1
> dc3                                  1     2     2   ---      15.2 2
> dc3                                  1     3     3   ---      12.9 3
> The problem goes away if I tell Xen to boot with options dom0_max_vcpus=1
> dom0_vcpus_pin.
> What's the difference between Xen boot options to limit vcpus for dom0 to
> /etc/xen/xend-config.sxp?
> I am running Xen 3.4.1-rc6 version.
>
>
>
>
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>
>

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