Openstack OverCommiting vCPU calculation

1) Calculate Threads, Core and Socket 

$ lscpu | grep -i -E  "^CPU\(s\):|core|socket"
 CPU(s):                8
 Thread(s) per core:    2
 Core(s) per socket:    4
 Socket(s):             1
Model name:            Intel(R) Core(TM) i7-3770 CPU @ 3.40GHz

2) vCPU calculation:

  

              vCPU= Thread(s) per core * Core(s) per socket * Socket(s)
                 vCPU = 2 *4 * 1 =8

3) Over Commiting Ratio :

             Dependends on CPU model can be increased upto 16 vCPUS

     nova.conf in compute node

                 [DEFAULT]                      

                        cpu_allocation_ratio = 4.0