iotest 240 is failing (was: Re: [PULL 20/22] virtio-scsi: add iothread-vq-mapping parameter)

[Thomas Huth <thuth@redhat.com>]

On 26/03/2025 11.43, Thomas Huth wrote:
> On 11/03/2025 17.00, Kevin Wolf wrote:
>> From: Stefan Hajnoczi <stefanha@redhat.com>
>>
>> Allow virtio-scsi virtqueues to be assigned to different IOThreads. This
>> makes it possible to take advantage of host multi-queue block layer
>> scalability by assigning virtqueues that have affinity with vCPUs to
>> different IOThreads that have affinity with host CPUs. The same feature
>> was introduced for virtio-blk in the past:
>> https://developers.redhat.com/articles/2024/09/05/scaling-virtio-blk-disk- 
>> io-iothread-virtqueue-mapping
> 
>   Hi Stefan!
> 
> This patch seems to cause some troubles with iotest 240 in raw (and some 
> other) mode:
> 
> 240   fail       [11:41:33] [11:41:34]   0.8s   (last: 0.8s)  output 
> mismatch (see tests/qemu-iotests/scratch/raw-file-240/240.out.bad)
> --- tests/qemu-iotests/240.out
> +++ tests/qemu-iotests/scratch/raw-file-240/240.out.bad
> @@ -46,11 +46,11 @@
>   {"execute": "device_add", "arguments": {"bus": "scsi0.0", "drive": "hd0", 
> "driver": "scsi-hd", "id": "scsi-hd0"}}
>   {"return": {}}
>   {"execute": "device_add", "arguments": {"bus": "scsi1.0", "drive": "hd0", 
> "driver": "scsi-hd", "id": "scsi-hd1"}}
> -{"error": {"class": "GenericError", "desc": "Cannot change iothread of 
> active block backend"}}
> +{"return": {}}
>   {"execute": "device_del", "arguments": {"id": "scsi-hd0"}}
>   {"return": {}}
>   {"execute": "device_add", "arguments": {"bus": "scsi1.0", "drive": "hd0", 
> "driver": "scsi-hd", "id": "scsi-hd1"}}
> -{"return": {}}
> +{"error": {"class": "GenericError", "desc": "Duplicate device ID 'scsi-hd1'"}}
>   {"execute": "device_del", "arguments": {"id": "scsi-hd1"}}
>   {"return": {}}
>   {"execute": "blockdev-del", "arguments": {"node-name": "hd0"}}
> Failures: 240
> Failed 1 of 1 iotests
> 
> Could you please have a look?

Ping!

The problem still persists in QEMU 10.0 :-(

  Thomas