Just Installed it, Newbie questions

[Jesse]

Hello,

I've just installed mamcached and everything is well.
I executed the command:
        memcached -u nobody -d -m 128 -l 72.xxx.xxx.xxx -p 11211

My questions are how to know memcached is currently running? how to
know the site performance has been improved?

Another question, the IP address in above command should be the main
IP of my site or 127.0.0.1?

Thanks.
Jesse