Re: [libvirt] [PATCH 3/8] Implement virDomain{Set, Get}BlockIoTune for the qemu driver

Hmm - passing nparams==1 to set just read_bytes_sec has the side effect of wiping out any existing total_iops_sec, even though those two parameters seem somewhat orthogonal, all because we zero-initialized the struct that we pass on to the monitor command. Is that intended? I can live with it (but it probably ought to be documented), but we may want to consider being more flexible, by using '0' to clear a previous limit, but initializing to '-1' to imply the limit does not change. Then the qemu_monitor_json code should only emit the arguments that are actually being changed, rather than blindly always outputting 6 parameters even when the user only passed in one parameter. But I'm okay delaying that to a separate patch based on whether others think it would be a good improvement.