Am 20.02.2017 um 16:30 hat Stefan Hajnoczi geschrieben: > I/O throttling parameters are missing from blockdev-add. Is this > intentional? > > I can imagine two solutions that do not need these parameters in > blockdev-add: > > 1. I/O throttling is implemented by a BlockDriver. Users are expected > to create the BDS themselves. This is a little awkward since > query-block *does* include the throttling parameters in its output > and we must preserve this behavior for existing users. > > 2. block_set_io_throttle must be used after blockdev-add. Suboptimal > because issuing two commands is not atomic (use transaction?). > > Thoughts?
The existing I/O throttling code is working on BlockBackends, but blockdev-add creates BlockDriverStates. So it can't possibly add throttling parameters. The currently recommended solution block_set_io_throttle. The other option to control BB level thorttling would be to add qdev properties to the block devices. In the long term, I think going with 1. and moving throttling to the block node level is the much nicer (and more flexible) option. Kevin
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