nginx的worker数目进程设置问题

nginx的worker_processes设为多少才合适呢？
搜索到原作者的话：
一般一个进程足够了，你可以把连接数设得很大。如果有SSL、gzip这些比较消耗CPU的工作，而且是多核CPU的话，可以设为和CPU的数量一样。或 者要处理很多很多的小文件，而且文件总大小比内存大很多的时候，也可以把进程数增加，以充分利用IO带宽（主要似乎是IO操作有block）。

    As a general rule you need the only worker with large number of
    worker_connections, say 10,000 or 20,000.

    However, if nginx does CPU-intensive work as SSL or gzipping and
    you have 2 or more CPU, then you may set worker_processes to be equal
    to CPU number.

    Besides, if you serve many static files and the total size of the files
    is bigger than memory, then you may increase worker_processes to
    utilize a full disk bandwidth.

    Igor Sysoev