Sun, you were asking about 'stratum requested a work restart'.  So I went through a certain amount of pain trying to reduce the chatiness and learned that in stratum its not as simple as just setting a poll setting and resetting the work restart request (as one would believe because of the interval passing).  There are many factors that influence the work restart:  rpc polling duration, merkle root changes (or tx list changes), someone mining the current rounds difficulty, stratum timeout between client-server, etc.