With object storage services becoming increasingly accepted as replacement for traditional file or block systems, it is important to effectively measure the performance of these systems. Thus people can compare different solutions or tune their systems for better performance. In this session, we present COSBench (Cloud Object Storage Benchmark), a benchmark tool that we are currently working on in Intel for cloud object storage systems. In addition, as a case study, we will demonstrate how we use COSBench to evaluate/analyze OpenStack* Swift performance and conduct optimizations.