Service function chaining (SFC) in the SDN/NFV architecture offers a flexible approach to end-to-end service provisioning in future networks. Analysis on the quality of service (QoS) guaranteed by SFC becomes an important research topic. The resource abstraction and dynamic elastic service provisioning enabled by SDN/NFV bring in new challenges to SFC performance evaluation that have not been fully addressed by existing approaches. In order to face such challenges, a novel modeling and analysis method is proposed in this paper for evaluating end-to-end service performance of SFC in the SDN/NFV architecture. Application of network calculus-based techniques in this paper makes the proposed modeling and analysis method agnostic to VNF implementations and adaptive to service capacity scaling; thus applicable to performance evaluation of SFC in SDN/NFV for dynamic elastic service provisioning.