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

[Sagi Grimberg]

On 7/4/24 08:37, Christoph Hellwig wrote:
> 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.

It solves a point problem that I don't have a good idea on how to solve. 
It can stay there, but we should
be careful before we choose to evolve it.