Re: [RFC workqueue/driver-core PATCH 1/5] workqueue: Provide queue_work_near to queue work near a given NUMA node

Tejun Heo
2018-10-02T18:41:33Z

Hello,

On Tue, Oct 02, 2018 at 11:23:26AM -0700, Alexander Duyck wrote:
> >Yeah, it's all in wq_select_unbound_cpu(). Right now, if the
> >requested cpu isn't in wq_unbound_cpumask, it falls back to dumb
> >round-robin. We can probably do better there and find the nearest
> >node considering topology.
>
> Well if we could get wq_select_unbound_cpu doing the right thing
> based on node topology that would be most of my work solved right
> there. Basically I could just pass WQ_CPU_UNBOUND with the correct
> node and it would take care of getting to the right CPU.

Yeah, sth like that. It might be better to keep the function to take
cpu for consistency as everything else passes around cpu.

> >>The question I have then is what should I do about workqueues that
> >>aren't WQ_UNBOUND if they attempt to use queue_work_near? In that
> >
> >Hmm... yeah, let's just use queue_work_on() for now. We can sort it
> >out later and users could already do that anyway.
>
> So are you saying I should just return an error for now if somebody
> tries to use something other than an unbound workqueue with
> queue_work_near, and expect everyone else to just use queue_work_on
> for the other workqueue types?

Oh, I meant that let's not add a new interface for now and just use
queue_work_on() for your use case too.

Thanks.

--
tejun