The moikrewny site is new to me, and a useful addition - cheers, Marc. The Knosala distribution map suggests that the name is Silesian, i.e., belonging to a mixed German-Czech-Polish province. German Knossalla, on the other hand is more scattered.
There is a German surname,Knöss, which is discussed on this site -
http://www.familie-greve.de/index.php?name=lexikonbut my ignorance of German prevents me from following the discussion.