[openstack-dev] [openstack-dev[[nova] Simple question about sorting CPU topologies
jaypipes at gmail.com
Tue Jun 20 16:58:44 UTC 2017
On 06/20/2017 12:53 PM, Chris Friesen wrote:
> On 06/20/2017 06:29 AM, Jay Pipes wrote:
>> On 06/19/2017 10:45 PM, Zhenyu Zheng wrote:
>>> Sorry, The mail sent accidentally by mis-typing ...
>>> My question is, what is the benefit of the above preference?
>> Hi Kevin!
>> I believe the benefit is so that the compute node prefers CPU
>> topologies that do
>> not have hardware threads over CPU topologies that do include hardware
>> I'm not sure exactly of the reason for this preference, but perhaps it
>> is due to
>> assumptions that on some hardware, threads will compete for the same
>> resources as other siblings on a core whereas cores may have their own
>> (again, on some specific hardware).
> Isn't the definition of hardware threads basically the fact that the
> sibling threads share the resources of a single core?
> Are there architectures that OpenStack runs on where hardware threads
> don't compete for cache/TLB/execution units? (And if there are, then
> why are they called threads and not cores?)
I've learned over the years not to make any assumptions about hardware.
Thus my "not sure exactly" bet-hedging ;)
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