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The licensing is based on physical cores regardless of using hyper-threading or not. You could ask your Oracle sales rep and get an "official answer".
Here is an Oracle Doc explaining it.
Edited by: user12273962 on Mar 15, 2013 5:48 AM
thanks for the reply but as I said I've already read that Oracle doc, it explains hard partitioning but doesn't detail the performance considerations i.e using vpus/threads across a single or multiple cores and the licensing implications.
Roddy Rodstein writes...
In short, in your env, 4 VCPUs = 4 threads = 2 cores = 1 Oracle CPU license.
I have an entire chapter of my on-line book the oracle cloud cookbook dedicated to hard partitioning.
I hope this helps: http://itnewscast.com/hard-and-soft-partitioning-oracle-vm
Thanks for that Roddy but what if the 4VCPUS / threads belong to 4 cores, then I assume this is a 2 processor license?
As stated in my question if I assign 4 threads from 2 cores, the licensing is for 2 cores ie 1 processor but will there be a performance impact?
and user12273962 states
I believe your sys admin is correct. The licensing is based on VCPU definitions regardless of using hyper-threading or not.
mmm I haven't found anything apart from you and my sys admin to support this?
Edited by: user1073175 on Mar 17, 2013 2:01 PM
Q: what if the 4VCPUS / threads belong to 4 cores, then I assume this is a 2 processor license?
A: In short, yes, 4 Cores = 2 CPU licenses. If Hyper-Threading is enabled the conversation is threads not cores, and 1 thread = .5 cores. To your point, 4VCPUS with Hyper-Threading = 1 CPU license, 4VCPUS without Hyper-Threading = 2 CPU licenses.
Q: As stated in my question if I assign 4 threads from 2 cores, the licensing is for 2 cores ie 1 processor but will there be a performance impact?
A: The only way to know for sure is to benchmark. That being said, typically I see hard partitioned VMs performing as good or a little better than non pinned VMs.
I hope this helps!
Sorry for posting a link you've already read. You just referenced the document by name and not by link and I didn't tie the two together.1 person found this helpful
This is the way I see it.... If you're using 4 cores, then you're using 4 cores. You can use multiple threads on a single core but single threading multiple cores still binds you to those cores. I don't officially speak for Oracle. Nor do most people who respond on this forum. Even Oracle employees that work for Oracle can't give you an official answer. You must to talk to your sales rep and they will get the answer from Oracle Licensing. They will give you the "Oracle answer". Oracle has entire group dedicated to Licensing. I just give my opinion. You're using 4 cores. When you run "xenpm" you can tell exactly what threads are associated with what cores. Pinning 4 threads out over 4 cores means you're using 4 cores. If you decide to pin 8 threads over 8 cores. Then you're using 8 cores. There are no guarantees that hyprethreading will only use a max of 50 percent of any single core. It depends on several different variables.
As to performance, A thread is a thread is a thread. When you pin threads you are dedicating that thread to the core you pin. There has long been debates over whether hyperthreading actually helps performance. In my opinion it does when you are have software that will actually use those threads to load balance request and you're running average CPU work loads. BUT, under high utilization..... I can't see how a second thread can help when the core itself is near maximum utilization. HT has gotten better over the years and OS support has gotten better. I still don't believe that hyperthreading actually helps systems under near max utilization. I've seen Intel quote a 30 percent improvement when if what they say is true, you should get more. I believe 30 percent is about right under normal CPU work loads. A maxed core is a maxed core.
Read this thread.
hard partitioning and hyperthreading and licensing and confusion
In the end, you need to ask your Sales rep and get the official "Oracle answer".
Edited by: user12273962 on Mar 18, 2013 6:58 AM