Re: [libvirt] [PATCH RFC 00/39] qemu: Add support for -blockdev

On Thu, Jul 26, 2018 at 17:04:19 +0800, Fam Zheng wrote: > On Thu, 07/26 10:44, Kevin Wolf wrote: > > Am 25.07.2018 um 17:57 hat Peter Krempa geschrieben: > > > This series adds support for starting and hotplug of disks with > > > -blockdev/blockdev-add. > > > > > > Blockjobs are not supported and thus the last patch should not be > > > applied yet as some refactoring of the jobs is required. > > > > > > At the beginning of the series there are a few cleanup patches which may > > > be pushed even at this point. > > > > > > The main reason this is in RFC state is that block stats reporting does > > > not work. > > > > > > The following command: > > > > > > {"execute":"query-blockstats","arguments":{"query-nodes":true}} > > > > query-nodes was added in commit f71eaa74c0b by Fam and Max, CCed. I'm > > not sure what it was needed for at all and the commit message doesn't > > help with that, but I suppose the addition was related to > > wr_highest_offset (see below). > > Yes, this was part of RHBZ 1158094. Sorry about the poor commit message. Well the problem is that when using -blockdev with 'query-nodes' false/not present you get a even more useless output: virsh qemu-monitor-command --pretty upstream '{"execute":"query-blockstats","arguments":{"query-nodes":false}}' { "return": [ ], "id": "libvirt-20" }

'query-named-block-nodes' don't provide the 'stats' section either: (other drives snipped)

Thus libvirt can't provide the stats it used to with -drive. Since we need to special-case the code for gathering stats for -blockdev it should not be a problem if e.g. query-named-block-nodes reported the stats section along. (perhaps with a boolean flag to do so which also could disable the nesting)

In either case we need the stats in the same extent as we had before with -drive and query-blockstats.