DISK IOPS / Throughput burst support
Since QEMU => 2.6 and LIBVIRT 0.8.8 there is support for IOPS bursting. For a specified amount of time a VM DISK can consume more IOPS / Throughput. See https://blogs.igalia.com/berto/2016/05/24/io-bursts-with-qemu-2-6/. So this is basically an extension of the already posibility in ONE to limit read, write, total IOPS / Bandwidth.