Communication breakdown: analyzing CPU usage in commercial Web workloads

There is increasing concern among developers that future Web servers running commercial workloads may be limited by network processing overhead in the CPU as 10Gb Ethernet becomes prevalent. We analyze CPU usage of real hardware running popular commercial workloads, with an emphasis on identifying networking overhead. Contrary to much popular belief, our experiments show that network processing is unlikely to be a problem for workloads that perform significant data processing. For the dynamic Web serving workloads we examine, networking overhead is negligible (3% or less), and data processing limits performance. However, for Web servers that serve static content, networking processing can significantly impact performance (up to 25% of CPU cycles). With an analytical model, we calculate the maximum possible improvement in throughput due to protocol offload to be 50% for the static Web workloads.