PCM returns different number of numa domains and sockets.

PCM returns different number of numa domains and sockets.

Hello. One more issue with PCM.  On our HW it returns different number of sockets and NUMA domains. Is it valid?

As far as I understand PCM uses GetLogicalProcessorInformationEx. It gets information for all relations and then builds CPU topology. But in my case returned buffer contains 2 records for RelationProcessorPackage and one for RelationNumaNode. It seems strange.



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Hello Alexander,

Is NUMA disabled in the bios?


Good point, I will check. But my assumption was that NUMA is always enabled and the only thing that affects NUMA behavior is a setting for memory adresses interleaving.

It seems like taskmanager, on newer versions of Windows server, had an option to show numa node number. Maybe it was buried in the 'shows processes, right click on a process to set affinity' popup window. But I think this was only on boxes with more than 1 socket.

You are right. The one that has consistent NUMA nodes/sockets count shows nodes in task manager and another doesn't

Hi Alexander,

there is also possibility to check for NUMA returned information with the help of debugger running in local kernel debugging mode.So you can compare the results with those returned by the other application.I suppose that at code level debugger also calls GetLogicalProcessorInformationEx.

Sometimes it is recommended to check some information with different tools.There could be possibility that generic API call will not be used and some custom driver will access kernel mode structures.

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