Re: [PATCH v3] blk-mq: dispatch kworker to housekeeping CPU when hctx cpumask is empty

[Daniel Wagner]

> While your nvme/070 test targets NVMe fabrics connect and passthrough
> request allocation, this fix is in core blk-mq (blk_mq_hctx_next_cpu) and
> affects deferred workqueue execution across all block devices. Using a new
> test based on null_blk would allow us to:
> 
>     1.  Target infrastructure for generic blk-mq workqueue placement testing
> 
>     2.  Easily configure a shallow queue depth or inject tag
>         exhaustion/busy conditions to reliably trigger asynchronous queue
>         dispatch (&hctx->run_work)
> 
>     3.  Trace workqueue:workqueue_execute_start to assert that no kblockd
>         worker executes on the isolated core
> 
> I'll put together a test case for tests/block/.

Sounds good to me! Thanks.