Re: [PATCH v3 15/15] blk-mq: use hk cpus only when isolcpus=io_queue is enabled

Daniel Wagner
2024-08-13T12:53:50Z

On Fri, Aug 09, 2024 at 11:23:58PM GMT, Ming Lei wrote:
> From above implementation, "isolcpus=io_queue" is actually just one
> optimization on "isolcpus=managed_irq", and there isn't essential
> difference between the two.

Indeed, the two versions do not differ so much. I understood, that you
really want to keep managed_irq as it currently is and that's why I
thought we need io_queue.

> And I'd suggest to optimize 'isolcpus=managed_irq' directly, such as:
>
> - reduce nr_queues or numgrps for group_cpus_evenly() according to
> house-keeping cpu mask

Okay.

> - spread house-keeping & isolate cpu mask evenly on each queue, and
> you can use the existed two-stage spread for doing that

Sure if we can get the spreading sorted out so that not all isolcpus are
mapped to the first hctx.

Thanks,
Daniel