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[Xen-devel] Ping³: [PATCH 1/2] core-parking: interact with runtime SMT-disabling
- To: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
- From: Jan Beulich <JBeulich@xxxxxxxx>
- Date: Mon, 15 Jul 2019 08:34:19 +0000
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- Cc: Stefano Stabellini <sstabellini@xxxxxxxxxx>, Wei Liu <wl@xxxxxxx>, Konrad Wilk <konrad.wilk@xxxxxxxxxx>, George Dunlap <George.Dunlap@xxxxxxxxxxxxx>, Tim Deegan <tim@xxxxxxx>, JulienGrall <julien.grall@xxxxxxx>, "xen-devel@xxxxxxxxxxxxxxxxxxxx" <xen-devel@xxxxxxxxxxxxxxxxxxxx>, Ian Jackson <ian.jackson@xxxxxxxxxx>
- Delivery-date: Mon, 15 Jul 2019 08:54:27 +0000
- List-id: Xen developer discussion <xen-devel.lists.xenproject.org>
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- Thread-topic: Ping³: [PATCH 1/2] core-parking: interact with runtime SMT-disabling
On 03.07.2019 13:29, Jan Beulich wrote:
>>>> On 27.05.19 at 11:36, wrote:
>>>>> On 12.04.19 at 13:41, wrote:
>>>>>> On 11.04.19 at 21:06, <andrew.cooper3@xxxxxxxxxx> wrote:
>>>> On 11/04/2019 13:45, Jan Beulich wrote:
>>>>> When disabling SMT at runtime, secondary threads should no longer be
>>>>> candidates for bringing back up in response to _PUD ACPI events. Purge
>>>>> them from the tracking array.
>>>>>
>>>>> Doing so involves adding locking to guard accounting data in the core
>>>>> parking code. While adding the declaration for the lock take the liberty
>>>>> to drop two unnecessary forward function declarations.
>>>>>
>>>>> Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
>>>>
>>>> I can certainly appreciate these arguments, but surely the converse is
>>>> true. When SMT-enable is used, the newly-onlined threads are now
>>>> eligible to be parked.
>>>
>>> And nothing will keep them from getting parked.
>>>
>>>> At the moment, this looks asymetric.
>>>
>>> It does, but that's a result of core_parking.c only recording CPUs
>>> it has parked, not ones it could park.
>>
>> Did my responses address your concerns?
>>
>> Jan
Ping?
Jan
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