Re: [Xen-devel] Hypervisor crash(!) on xl cpupool-numa-split

[George Dunlap <George.Dunlap@xxxxxxxxxxxxx>]

On Tue, Feb 8, 2011 at 5:43 AM, Juergen Gross
<juergen.gross@xxxxxxxxxxxxxx> wrote:
> On 02/07/11 16:55, George Dunlap wrote:
>>
>> Juergen,
>>
>> What is supposed to happen if a domain is in cpupool0, and then all of
>> the cpus are taken out of cpupool0?  Is that possible?
>
> No. Cpupool0 can't be without any cpu, as Dom0 is always member of cpupool0.

If that's the case, then since Andre is running this immediately after
boot, he shouldn't be seeing any vcpus in the new pools; and all of
the dom0 vcpus should be migrated to cpupool0, right?  Is it possible
that migration process isn't happening properly?

It looks like schedule.c:cpu_disable_scheduler() will try to migrate
all vcpus, and if it fails to migrate, it returns -EAGAIN so that the
tools will try again.  It's probably worth instrumenting that whole
code-path to make sure it actually happens as we expect.  Are we
certain, for example, that if a hypercall continued on another cpu
will actually return the new error value properly?

Another minor thing: In cpupool.c:cpupool_unassign_cpu_helper(), why
is the cpu's bit set in cpupool_free_cpus without checking to see if
the cpu_disable_scheduler() call actually worked?  Shouldn't that also
be inside the if() statement?

 -George

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