Studies　have　been　done　on　the　reliability　modelling　of　systems　with　performance　sharing　mechanism,　which　is　applicable　in　energy　systems,　computing　systems,　pollution　treatment　systems,　etc.　Most　existing　researches　share　a　common　assumption　that　every　component　must　satisfy　its　demand　after　proper　performance　redistribution,　i.e.,　performance　sharing.　However,　some　systems　may　allow　certain　extent　of　performance　deficiency.　In　this　paper,　we　consider　a　system　with　performance　sharing　mechanism　where　the　system　works　as　long　as　the　summed　weighted　deficiency　is　smaller　than　the　reliable　threshold　(pre-set　value)　after　two　types　of　performance　sharing:　surplus　redistribution　and　maximal　redistribution.　The　amount　of　shared　performance　is　limited　by　the　capacity　of　bandwidth.　A　universal　generating　function　technique　is　adopted　to　evaluate　the　system　reliability,　and　numerical　examples　are　presented　to　illustrate　the　applications.