Am 18.05.2018 um 20:41 hat Dr. David Alan Gilbert geschrieben: > * Kevin Wolf (kw...@redhat.com) wrote: > > Before we can make x-blockdev-create a background job, we need to > > generalise the job infrastructure so that it can be used without any > > associated block node. > > Is there any relationship between what this does, and what > Marc-André's 'monitor: add asynchronous command type' tries to do? > (See 20180326150916.9602-1-marcandre.lur...@redhat.com 26th March)
Depends on who you ask. :-) In a way, yes. Marc-André's async commands are for long-running operations and jobs are for long-running operations. However, they are for a different kind of "long-running". Basically, Marc-André's work is for commands that are generally quick, but perform some blocking operation. Usually commands that are currently implemented synchronously, but always bothered us because they block the VM for a while. They take maybe a few seconds at most, but you really don't want them to block the guest even for short time. The important part here is you don't want to modify the operations while they're running, they just send their return value when they are done. (In the latest version, Marc-André even made sure not to modify the wire protocol, so IIUC the commands aren't really async any more in the sense that you can have multiple commands running, but they are just non-blocking in the sense that the guest can keep running while they are doing their work.) In comparison, jobs are typically really long running, like several minutes (like copying a whole disk image). Some of them can even run indefinitely (like mirroring) until you explicitly tell them to stop. You want to continue using the monitor while they are running, and to be able to manage them at runtime (pause/resume/set speed/cancel/...). So I think both address different problems. Kevin
