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Re: [Xen-devel] Core parking feature enable

Jan Beulich wrote:
>>>> On 02.03.12 at 10:42, Haitao Shan <maillists.shan@xxxxxxxxx> wrote:
>> I would really doubt the need to create a new interface of receiving
>> ACPI event and sending to user land (other than existing native
>> kernel) specifically for Xen. What's the benefit and why kernel
>> people should buy-in that?
> Receiving ACPI events??? I don't recall having seen anything like that
> in the proposed patch (since if that was the case, I would probably
> agree that this is better done in kernel/hypervisor). Was what got
> sent out perhaps just a small fraction of what is intended, and was it
> forgotten to mention this?
> Jan

Yes, it does need to intercept ACPI PAD notify then handle it similar way as 
native kernel did. The logic is at dom0 '[PATCH 3/3] Xen pad logic and 
notification' as attached.
Sorry I didn't give explicit and detailed explanation at the patch description 
(defaultly I thought you know native acpi pad, so I ignored the background 
story :-)
I will add more detailed description at dom0 patch 3/3.


>> Core parking is a platform feature, not virtualization feature.
>> Naturally following native approach is the most efficient. Why do you
>> want to create yet another interface for Xen to do that?
>> Shan Haitao
>> 2012/3/1 Jan Beulich <JBeulich@xxxxxxxx>:
>>>>>> On 01.03.12 at 15:31, "Liu, Jinsong" <jinsong.liu@xxxxxxxxx>
>>>>>> wrote: 
>>>> Jan Beulich wrote:
>>>>>>>> On 01.03.12 at 12:14, "Liu, Jinsong" <jinsong.liu@xxxxxxxxx>
>>>>>>>> wrote: 
>>>>>> Unfortunately, yes, though cumbersome is not basic reason user
>>>>>> space approach is not preferred. Core parking is a power
>>>>>> management staff, based on dynamic physical details like cpu
>>>>>> topologies and maps owned by hypervisor. It's natural to
>>>>>> implement 
>>>>> CPU topology is available to user space, and as far as I recall
>>>>> your hypervisor patch didn't really manipulate any maps - all it
>>>>> did was pick what CPU to bring up/down, and then carry out that
>>>>> decision. 
>>>> No. threads_per_core and cores_per_socket exposed to userspace is
>>>> pointless to us (and, it's questionable need fixup).
>>> Sure this would be insufficient. But what do you think did
>>> XEN_SYSCTL_topologyinfo get added for?
>>>> Core parking depends on following physical info (no matter where
>>>> it implement): 
>>>> 1. cpu_online_map;
>>>> 2. cpu_present_map;
>>>> 3. cpu_core_mask;
>>>> 4. cpu_sibling_mask;
>>>> all of them are *dynamic*, especially, 3/4 are varied per cpu and
>>>> per online/offline ops.
>>> Afaict all of these can be reconstructed using (mostly sysctl)
>>> hypercalls. 
>>> Jan
>>> _______________________________________________
>>> Xen-devel mailing list
>>> Xen-devel@xxxxxxxxxxxxx
>>> http://lists.xen.org/xen-devel

Attachment: 0003-Xen-pad-logic-and-notification.patch
Description: 0003-Xen-pad-logic-and-notification.patch

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