Test Cases Description

Virtual machines are used by IT departments to provide better hardware utilization and to isolate users and programs from each other. We explore how configuration changes affect the throughput of virtual machines hosted on ESX Server during CPU intensive workloads. In particular we explore how Hyper-Threading, Virtual SMP, and the amount of RAM allocated affect throughput. Hyper-Threading is Intel’s implementation of simultaneous multithreading technology and was introduced with the Xeon processor. Virtual SMP allows ESX Server to host virtual machines with two virtual processors. Our tests were run on two Dell 6650 quad processor 2.20 GHz Xeon servers with 16GB of RAM, a Gigabit Ethernet NIC, and a 1.3 TB SAN. Our benchmarks were run on Linux kernel 2.4.21-15.ELsmp and compiled by gcc 3.2.3 unless specifically stated otherwise. We used SPEC’s cpu2000 benchmark suite to obtain our results. No attempt was made to optimize the benchmarks for the virtual machines and default settings were used in all cases. Unused virtual machines were suspended before each test. Each benchmark was run five times to ensure that the results were consistent and repeatable. We used the RDTSC instruction to time the benchmarks. The table below summarizes our benchmark test cases