Determine if an Host has Hypertreading enabled

rtjdamen

julien-f i have discussed with our developer and i would like to ask you the following

As per their feedback, the XCP-NG API itself gives the double amount of cores per CPU in its output.

For a 2 CPU x 16 core configuration, the system gives 32 cores per CPU, instead of 16.

Please consult with Vates, if they can modify the current API/CPU core count enumeration, to show the actual physical CPU core counts, instead of logical ones in the API output.

julien-f

rtjdamen Please give me the name of the class field and its value in the XAPI and the same in XO REST API so we can compare.

julien-f

rtjdamen You'll likely just need to take a look at cpus field and multiply cores and sockets.

rtjdamen

julien-f Hi julien, the cpu field gives a incorrect view of the real world. because of the hypertreading enabled it gives you double the number of cpu cores there actually is. We are looking for a good way to determine REAL PHYSICAL cores. Reason for that is Microsoft is licensing datacenter licenses on a physical core basis. can u help us with the correct way to find this out?
in Xoa there is a field shown for hypertreading enabled. if that value is shown into the rest api we are there, but if it is not we need a different way to find out if this is enabled or not.

olivierlambert

julien-f the HT detection we created (via a plugin) is already detecting "threads_per_core" or something like that. IIRC, in XO, if it's >1, we can tell hyperthreading is enabled. So we might need to expose thread per core or something equivalent we did in XO directly in the REST API

julien-f

rtjdamen REST API now expose the SMT status: https://github.com/vatesfr/xen-orchestra/commit/7fc5d62ca95ba91666f5d5a2268a7871c484ac6a

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julien-f committed to vatesfr/xen-orchestra

feat(xo-server/rest-api): export hosts' SMT status

Fixes https://xcp-ng.org/forum/post/71374

olivierlambert

Also, we are working to get the info directly in XAPI: https://github.com/xapi-project/xen-api/issues/5462

olivierlambert created this issue in xapi-project/xen-api

closed SMT discoverability: add thread_per_core info in host.cpu_info #5462

rtjdamen

julien-f do i need to update anything on my end to get this visible? or is this centrally managed?

julien-f

rtjdamen You need to rebuild your xo-server if you are using it from the sources. I you are using an official XOA, you will need to wait for the next release (last day of the month) and upgrade using the latest channel.

rtjdamen

olivierlambert is it possible to apply this changes allready to our XOA? it would help with the development.