On 09/24/09 17:27, Jiang, Yunhong wrote:
> Do you mean logical offlining or physical offlining? I think logical
> offlining is tested long before. For physical offlining, I implement it but I
> have no platform to test still.
>
> In fact , it is a tricky to physical offlining a cpu (or, more precisely
> speaking, socket) because that means we need offline all memory behind a
> socket. But it can be used for socket migration, i.e. put down the old CPU
> and bring up a spare CPU, in that situation, we need CPU offlining. We are
> still working on socket migration.
>
I see. I guess it makes it hard when the CPUs are also the memory
controllers.
> Yes, also MCE.
> And, are you sure currently the microcode driver really not called in hotplug
> of vcpus? Will vcpu online not trigger the CPU_online notifier?
>
I would expect vcpu hotplug will call the usual notifiers as expected,
but drivers which really care about pcpus don't have much use for those
notifications.
>> This could do with some clarification. Is this case that a newly
>> added pcpu already appears to be online?
>>
> Because the vIRQ notification for pcpu hotplug from xen hypervisor is async,
> so maybe it happens after the pcpu is onlined by user. (i.e., the online
> notification and hotplug notification is merged)
>
I'm not sure I follow. Are you saying this is an expected race, and
that this printk is just for debugging?
>> __init?
>>
>> Also I prefer names of the form subsystem_action, so
>> xen_pcpu_info_init().
>>
> Sorry, what do you mean of subsystem_action? I didn't find definition for it.
>
I meant "<subsystem>_<action>()".
>> So when does this interrupt get raised? Is the full flow:
>>
>> 1. ACPI raises SCI
>> 2. dom0 catches that and gets the new pcpu event
>> 3. dom0 notifies Xen that the pcpu exists
>> 4. xen interrupts dom0 saying that a new pcpu exists
>> 5. dom0 processes the list and adds it to sysfs
>> 6. usermode onlines the cpu for Xen's use
>>
> And there is also step 7, Xen interrupt dom0 saying a new pCPU is onlined.
> Through step 7, dom0 will have the life cycle of the pCPU.
>
OK, I see.
J
_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-devel
|
Home