Re: [PATCH 5/7] nvmet-tcp: add wq_unbound module parameter

Sagi Grimberg
2024-06-26T13:44:38Z

Please leave this outside of the series.

On 26/06/2024 15:13, Hannes Reinecke wrote:
> For high loads the default scheme of queueing work on the receiving
> cpu might lead to cpu starvation and 'CPU hogged' messages.

In which workloads have you seen this print?
Can you place the print in the commit msg?

> This patch provides an 'wq_unbound' module parameter to let the
> workqueue mechanism do scheduling decisions.

It was intentional that we maintain locality of the nic to the backend
drive.

I'm not saying that we may not want to do this, but we need a justification
as to why. Was this reported by users? or observed by you?

What about rdma btw? That also runs in a workqueue context. Plus with
rxe/siw
it is also writing to normal udp/tcp sockets.