Qemu can use two different methods to submit disk I/O requests. The default method, "io=threads", uses a thread pool to submit these requests synchronously, while the alternate method, "io=native", uses a single thread to submit these requests asynchronously. We were curious if the default method provided the best overall throughput, so we tested both under a wide array of storage configurations. This included the use of solid state and rotational disks, different host filesystems, and even using a network file system. This paper consists of our analysis results, challenges and improvements.
