Please refer to the following documentation when running Timing Analysis.
NOTE: This answer record is part of the Xilinx Timing Analysis Solution Center (Xilinx Answer 40832). The Xilinx Timing Analysis Solution Center is available to address all questions related to Timing Analysis. Whether you try to setup timing constraint on a new design or troubleshooting a timing violation, use the Timing Analysis Solution Center to guide you to the right information.
Timing Analysis General Resources