Kevin Wolf <kw...@redhat.com> writes: > Am 18.09.2023 um 18:16 hat Stefan Hajnoczi geschrieben: >> virtio-blk and virtio-scsi devices will need a way to specify the >> mapping between IOThreads and virtqueues. At the moment all virtqueues >> are assigned to a single IOThread or the main loop. This single thread >> can be a CPU bottleneck, so it is necessary to allow finer-grained >> assignment to spread the load. >> >> Introduce DEFINE_PROP_IOTHREAD_VQ_MAPPING_LIST() so devices can take a >> parameter that maps virtqueues to IOThreads. The command-line syntax for >> this new property is as follows: >> >> --device >> '{"driver":"foo","iothread-vq-mapping":[{"iothread":"iothread0","vqs":[0,1,2]},...]}' >> >> IOThreads are specified by name and virtqueues are specified by 0-based >> index. >> >> It will be common to simply assign virtqueues round-robin across a set >> of IOThreads. A convenient syntax that does not require specifying >> individual virtqueue indices is available: >> >> --device >> '{"driver":"foo","iothread-vq-mapping":[{"iothread":"iothread0"},{"iothread":"iothread1"},...]}' >> >> Signed-off-by: Stefan Hajnoczi <stefa...@redhat.com> > > When testing this, Qing Wang noticed that "info qtree" crashes. This is > because the string output visitor doesn't support structs. I suppose > IOThreadVirtQueueMapping is the first struct type that is used in a qdev > property type. > > So we'll probably have to add some kind of struct support to the string > output visitor before we can apply this. Even if it's as stupid as just > printing "<struct IOThreadVirtQueueMapping>" without actually displaying > the value.
The string visitors have been nothing but trouble. For input, we can now use keyval_parse() and the QObject input visitor instead. Comes with restrictions, but I'd argue it's a more solid base than the string input visitor. Perhaps we can do something similar for output: create a suitable formatter for use it with the QObject output visitor, replacing the string output visitor.