On-Line Transaction Processing (OLTP) workload is an important application in commercial service domain. Chip multiprocessor (CMP) is main stream of processor development. Performance characters of OLTP in CMP become a crucial benchmark for design and performance analysis of CMP server system. System level performance characters of OLTP on AMD quad-core system is presented in the paper. According to system level performance, we present a three stages model for OLPT in view of number of clients.