Swap Disk Microbenchmarks

Denali stripes VM swap regions across physical disks. To better understand factors that influence swap performance at scale, we benchmarked Denali's disk latency and throughput for up to three attached physical disks. The results are presented in Table 1; all measured throughputs and latencies were observed to be limited by the performance of the physical disks, but not the Denali isolation kernel. For three disks, a shared PCI bus became the bottleneck, limiting sequential throughput.

 

Table 1: Swap disk microbenchmarks: latency (ms), random throughput (MB/s), and sequential throughput (MB/s) versus the number of disks. Numbers separated by a slash are for reads and writes, respectively.