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I'm running Hyper-V on Windows 8.1 x64. I've created a Windows 8.1 x64 Gen2 virtual machine using all the default settings, except that I changed the "Number of virtual processors" from 1 to 2. When I boot up the VM, the VM only shows one processor. What am I missing?

Suraj
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    What information are you looking at? Task Manager? By default Windows 8 shows a unified CPU % graph, not one per CPU, so that could be mistaken for only 1 vCPU. You should see a "Virtual processors" count on the same screen that lists actual # of virtual processors – Joshua McKinnon Sep 11 '14 at 17:38
  • I was looking at Task Manager and you are right, I see 2 virtual processors and 1 socket. What does this mean from Windows' perspective? Does think it has 2 cores to distribute load or just one doubly-powerful core? – Suraj Sep 11 '14 at 18:03
  • Yes, it sees it as two independent processors / cores. It's working as you specified (2 virtual processors). If you want the graph to change, right click on the graph and choose "Change Graph To -> Logical Processors" and you'll see each virtual CPU usage separately. – Joshua McKinnon Sep 11 '14 at 19:35

1 Answers1

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  1. Run msconfig.exe
  2. Go to Boot tab
  3. Click on Advanced Options
  4. Verify "Number of Processors" is either unchecked or checked with the correct processor count

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gtirloni
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  • Works! Is this purely cosmetic or does it change the mechanics of how Windows interacts with those processors? Is Windows now in a better position to handle multiple simultaneously running processes? – Suraj Sep 11 '14 at 18:05
  • By default Windows will use all processors it can. This option is usually used to lower the number of used processes (for any reason). If you've 2 processors and define Windows to use 2 processors, nothing changes in the process scheduler regarding CPU timeslots, etc. It'd be a no-op. – gtirloni Sep 11 '14 at 18:07