The option IO Thread can only be used when using a disk with the VirtIOcontroller, or with the SCSI controller, when the emulated controller type isVirtIO SCSI single. With IO Thread enabled, QEMU creates one I/O thread perstorage controller rather than handling all I/O in the main event loop or vCPUthreads. One benefit is better work distribution and utilization of theunderlying storage. Another benefit is reduced latency (hangs) in the guest forvery I/O-intensive host workloads, since neither the main thread nor a vCPUthread can be blocked by disk I/O.