yes, i believe its reporting the number of processors in the current group only, not across all groups.

attached output of windows sysinternals/coreinfo showing 2 processor groups

see https://github.com/giampaolo/psutil/issues/771 for some further disucssion of this topic

the maintainer of psutil asked me to raise this bug, also had a quick check on #python IRC. Its my first bug on bugs.python.org so if you need more info just let me know