[PATCH 2/4] nvme-tcp: align I/O cpu with blk-mq mapping

[Christoph Hellwig]

On Wed, Jul 03, 2024 at 05:19:39PM +0300, Sagi Grimberg wrote:
>
>
> On 03/07/2024 16:50, Hannes Reinecke wrote:
>> When 'wq_unbound' is selected we should select the
>> the first CPU from a given blk-mq hctx mapping to queue
>> the tcp workqueue item. With this we can instruct the
>> workqueue code to keep the I/O affinity and avoid
>> a performance penalty.
>
> wq_unbound is designed to keep io_cpu to be UNBOUND, my recollection
> was the the person introducing it was trying to make the io_cpu always be
> on a specific NUMA node, or a subset of cpus within a numa node. So he uses
> that and tinkers with wq cpumask via sysfs.

Honestly, I think we really should kill this unbound module paramter
before it causes more harm.