sockets - Discussion of the Java SocketChannel, performance -

i investigating performance of socketchannel.

in details, if have socketchannel such like:

socketchannel sc = selectionkey.channel(); 

and have bytebuffer send,

sc.write(buffer); 

then determine time consumed write() function?

in detail, asking happens in bottom layer, or saying, detailed implementation of method. signals successful write() function? waiting ack packet other end?

thanks