参考网上的，给memcache增加注释
If using Linux, you need a kernel with epoll. Sure, libevent will
work with normal select, but it sucks.
epoll isn’t in Linux 2.4, but there’s a backport at:
http://www.xmailserver.org/linux-patches/nio-improve.html
You want the epoll-lt patch (level-triggered).
If you’re using MacOS, you’ll want libevent 1.1 or higher to deal with
a kqueue bug.
Also, be warned that the -k (mlockall) option to memcached might be
dangerous when using a large cache. Just make sure the memcached machines
don’t swap. memcached does non-blocking network I/O, but not disk. (it
should never go to disk, or you’ve lost the whole point of it)
Want to contribute? Up-to-date pointers should be at: