Am 16.01.2026 um 15:39 hat Fiona Ebner geschrieben: > With '-drive', it is possible to specify the throttle configuration > directly on the commandline. Add the possibility to do the same when > using the modern way with '-blockdev' and a front-end device. Using a > throttle filter block node is not always an option: in particular, the > mirror block job operates on a root block node and it might be desired > to throttle only the guest IO, but not to the block job.
Hm, is there still a reason why we require a root node for the source? > There already is a 'block_set_io_throttle' QMP command, but it's nicer > to be able to do it via the commandline too. > > Signed-off-by: Fiona Ebner <[email protected]> > --- > > Hope I didn't miss a way to do this already. > > Should changing via qom-set be supported? Currently, an attempt fails: > > Error: Attempt to set property 'throttle-group' on device 'scsi0' > > (type 'scsi-hd') after it was realized > but there already is the 'block_set_io_throttle' QMP command. It would be nice, but I don't think runtime writable properties are used much in devices because I believe this would have to be done with plain QOM properties, i.e. outside of qdev. Though if it's actually easy, we could consider implementing it. > hw/block/block.c | 15 +++++++++++++++ > include/hw/block/block.h | 4 +++- > tests/qemu-iotests/172.out | 38 ++++++++++++++++++++++++++++++++++++++ > 3 files changed, 56 insertions(+), 1 deletion(-) Looks good to me, though maybe we could also use a qemu-iotests case that actually tries to set the property instead of only updating the output everywhere for having no throttle group. Kevin
