Performance characterization of iSCSI processing in a server platform

The iSCSI protocol is a key building block for enabling IP-based network storage. High performance iSCSI implementations that can support multi-gigabit storage traffic throughput at low latencies are important in facilitating the widespread deployment of this technology. Motivated by this, our work presented in this paper focuses on analyzing the underlying architectural characteristics of iSCSI packet processing and quantifying its compute/memory requirements. Our analysis and characterization methodology is based on in-depth measurement experiments of iSCSI packet processing performance on Intel^® Xeon™ processor, running the Red Hat Linux operating system. Our measurement data shows the achievable throughput and consumed CPU utilization at different disk I/O sizes. We also study the overhead of integrity checks on iSCSI performance by enabling CRC computation. To understand the source of the iSCSI processing costs, we then do a detailed analysis of the architectural characteristics in terms of path length, cycles spent per instruction, cache misses at all levels and branch mispredictions.