If you search the forums, you will find many (and I do mean many!) discussion on this exact topic. Basic rules of thumb:
- Create your VMs with one vCPU, make sure you use the uni-processor HAL
- If your VM can REALLY USE additional CPUs (i.e. 3D Studio Max, a busy database or similar), then add vCPUs incrementally until you achieve acceptable performance. Remember...creating even one vSMP VM will have a negative impact on the performance of ALL other VMs running on your host (search for vSMP and schedule) - AND it impacts the number of VMs you can run in an HA cluster (search for HA and SLOT).
- After updating your VM to vSMP, make sure you update the HAL on your guest OS to be multi-processor aware
Ken Cline
Technical Director, Virtualization
Wells Landers
VMware Communities User Moderator
Ken Cline
VMware vExpert 2009
VMware Communities User Moderator
Blogging at: http://KensVirtualReality.wordpress.com/
