Zhang Chen <[email protected]> writes:
> On Mon, Aug 24, 2026 at 3:24 PM Markus Armbruster <[email protected]> wrote:
>>
[...]
>> Back to what got us there. My attempt to test query-iothreads showing
>> holders failed, because monitors are not usable for this test. Please
>> show me how to test this. Ideally, a simple command line and a few
>> simple monitor commands ending with a query-iothreads that shows
>> holders.
>>
>
> Thanks. Here is a reproducer that also exercises holder removal and
> registration by another device type:
>
> $ qemu-system-x86_64 \
> -S -nodefaults -display none \
> -object iothread,id=iothread0 \
> -blockdev driver=null-co,node-name=null0 \
> -qmp stdio
>
> First, hotplug a virtio-scsi device and query the IOThread:
> {"execute":"qmp_capabilities"}
> {"execute":"query-iothreads"}
>
> {"return": [{"poll-shrink": 2, "thread-id": 4002255, "poll-weight": 3,
> "aio-max-batch": 0, "poll-grow": 2, "holders": [], "poll-max-ns":
> 32768, "id": "iothread0"}]}
>
> {"execute":"device_add","arguments":{"driver":"virtio-scsi-pci","id":"scsi0","iothread":"iothread0"}}
> {"execute":"query-iothreads"}
>
> {"return": [{"poll-shrink": 2, "thread-id": 4002255, "poll-weight": 3,
> "aio-max-batch": 0, "poll-grow": 2, "holders": [{"qom-path":
> "/machine/peripheral/scsi0/virtio-backend", "type": "qom-object"}],
> "poll-max-ns": 32768, "id": "iothread0"}]}
>
> The result contains:
> > "holders": [
>
> Remove the device:
>
> {"execute":"device_del","arguments":{"id":"scsi0"}}
> {"return": {}}
>
> {"execute":"query-iothreads"}
> {"return": [{"poll-shrink": 2, "thread-id": 4002255, "poll-weight": 3,
> "aio-max-batch": 0, "poll-grow": 2, "holders": [], "poll-max-ns":
> 32768, "id": "iothread0"}]}
>
> And use the HMP is the same logic, just need change the "-qmp" to "-monitor":
> $ qemu-system-x86_64 \
> -S -nodefaults -display none \
> -object iothread,id=iothread0 \
> -blockdev driver=null-co,node-name=null0 \
> -monitor stdio
>
> (qemu) info iothreads
> iothread0:
> thread_id=4005900
> holders=
> poll-max-ns=32768
> poll-grow=2
> poll-shrink=2
> poll-weight=3
> aio-max-batch=0
>
> .......
This serves nicely, thanks!
[...]
