VRS server: How many work processes should I give nginx?

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http://serverfault.com – On a Dual Intel Xeon E5649 shared server with my VPS running nginx. On my own machine I give nginx the same number of worker_processes that I have cores. But there's no competing resources on my local machine. I'm just wondering how this translates to a VRS type virtual server running on the above processor? Is the optimum still one per core? (HowTos)